Broken Symmetry

by Trick Question

Rating: teen
Tags: Moondancer, Science Fiction, Profanity, Violence, Princess Celestia, Narcotics, Twilight Sparkle, Drama, My Little Pony: Friendship is Magic, Starlight Glimmer, Romance, Princess Luna
Length: 59688

Somepony is sabotaging Moondancer's research. When Twilight offers to help, the two friends discover a dangerous secret.

Somepony is sabotaging Moondancer's research project.

Twilight Sparkle suspects Starlight Glimmer may be responsible. She enlists the Canterlot Royal Guard to protect Moondancer, and offers to help with her research.

Soon, however, the two ponies discover an unexpected side effect of Moondancer's research: one with dangerous consequences for all of Equestria—and possibly even their friendship.

Inspired by The Writeoff Association's "Out of Time" contest.

Now featured on Equestria Daily.

Published 2015-12-07 01:50:01 UTC
Last updated 2016-05-23 23:45:59 UTC

A Mysterious Mare

I didn't notice Twilight Sparkle until she was standing right in front of me.

"Moondancer?" said Twilight, gingerly taking her seat on the other side of the small cafe table.

My hooves were jittery. I was pretty sure I'd have spilled my coffee if I were holding it by hoof instead of magic. I telekinetically set the mug down and looked up to my former and once-again friend. I wasn't good at reading faces, but Twilight Sparkle seemed concerned. Maybe it was obvious I was on my fourth cup.

"Thanks for coming?" I said. I tried to hide the surprise from my voice, but I probably failed. I wasn't good at that sort of thing either.

"Of course! That's what friends are for," smiled Twilight. I waited while she ordered a hay smoothie from a passing waiter. All the while, I felt a certain tension creeping up my spine.

"Well, you're a princess," I finally replied, "so I assume you're really busy. I appreciate you coming on short notice."

Twilight shrugged. "It can get busy sometimes, but with the boundaries of my kingdom still sketchy I've been able to dodge a lot of responsibilities so far. Besides, your note sounded urgent, and there wasn't a lot of information—"

"Sorry about that," I interrupted her. "But now that we're talking, there's another reason I didn't expect you to show up. Can you tell me who this is?"

I pulled the photograph from my saddlebag and slid it across the table. Twilight leaned in and examined it curiously. The image had already been burned into my retinas: a bright white flash in the profile shape of a unicorn mare, standing in front of a shiny metal door.

"What's wrong with... wait, is she teleporting?" asked Twilight.

"Sure looks like it." I pushed my glasses back up to the bridge of my muzzle with magic.

"Moondancer, now I have to ask. What is this about?" As Twilight spoke, a waiter dropped off her smoothie and left without saying a word. That was fast, I thought. Being a princess clearly has its advantages.

I took a sharp breath. "Somepony is sabotaging my research, which I'll be happy to familiarize you with later, if you like. I set up an automatic camera, and it took this picture of her."

It took only a moment before it dawned on her.

"Moondancer, you don't think this is me, do you?" she gasped.

"Not anymore," I admitted, feeling a great weight lift from my withers. I exhaled a huge breath of air before continuing. "Naturally, I didn't want to believe that in the first place, but the picture is rather damning."

"She has bangs just like you and I," Twilight whispered, shaking her head in disbelief as she studied the image. "But the aura's impossible to match. This must have been taken right at the peak of the mana surge, and the light overwhelmed your camera's chroma thresholds."

"Yeah, I figured. But it's clearly a mare, relatively young, with straight bangs, don't you agree?" I asked. "I was hoping—if it wasn't you, of course—that you might have some ideas on who. Even among mages, teleportation is a hard spell to master on command."

"That's an understatement," said Twilight, and she leaned back in her chair to think. "Unless I misremember, you and I were the only two ponies in our graduating class to pull it off in time for commencement." She held the smoothie up in her right forehoof to drink from it, which struck me as odd.

"Correct; and ours was an exceptional year. The modal number of graduates who can teleport is zero, and there haven't been any 'porters in the two years following our class, or the three prior," I said, then paused as my curiosity got the better of me. "Um, this is rather off-topic, but can I ask you something personal?"

Twilight blushed, which also struck me as odd. I had no idea what that might mean, but I decided then to stop worrying about reading her behavior. Even if she used to be bad at friendship, you probably don't become the Princess of Friendship by being untrustworthy, right? Besides, I kind of liked her. We had a lot in common, and we even looked similar. Staring at Twilight Sparkle was almost like looking into a funhouse mirror: there was just enough symmetry there that I could recognize my own disturbing reflection looking back at me. Minus the glasses, of course.

"S-sure, ask away," Twilight said, and smiled weirdly. Then she nervously licked some congealed hay from her teeth.

"You're holding your cup in your right hoof," I said, pointing at her hoof.

"Oh. Well, I'm right-hooved. Aren't most ponies...?" she asked.

"I mean you're not using telekinesis to hold your cup. I'm just curious why."

"Oh!" said Twilight, and the muscles at the borders of her muzzle relaxed. "That's just, well... I try to use my hooves as much as possible in public, these days. It seems to put other ponies at ease," she explained. "Especially in Ponyville, with all the earth ponies who live there. Being a princess means some ponies look up to you like you're not even a real person, and it gets awkward."

I nodded. "I see. Anyway, I can't get records from Celestia's School from further back than 996 without leaving a paper trail, so I haven't tried yet. I suppose it could always be a grad student or an independent study, but those are kind of rare," I said. "To be perfectly honest, aside from the older ponies who teach at the School, I don't know anypony else who can teleport. Although, have you heard of a pony named Trixie Lulamoon?"

Twilight rolled her eyes. "Ah, Trixie. Yes, we've crossed paths. I'm not sure what you've heard, but Trixie can't teleport—she uses illusion magic to fake it. Even if she could, she'd never cut her forelock that short." She paused for a moment to take a sip of hay. "Until recently, I've only known one other mare who could do it. Celestia's protege before me, Sunset Shimmer."

"Could it be her?" I asked. I rocked a little in my seat, impatiently waiting for the precious knowledge in that thick purple head to come spilling out onto the table.

"No. She was evil, but she's been reformed for quite a while. And she doesn't even live in this dimension anymore," said Twilight.

I blinked a few times in rapid succession. "I'm... just going to assume that makes sense," I said.

Twilight grinned sheepishly. "Sorry. It's a long story. I suppose Sunset might have an evil counterpart in the other dimension who somehow wandered over to our world, but she'd have no motive. Besides, her forelock doesn't match," she said, levitating the picture up close to her face. Then, Twilight Sparkle gasped and her eyes drew open wide.

"What is it?" I asked, as my hoof nervously tapped at the table leg.

"Oh no. It could be her," she whispered. "No... I can't believe it."

"Who? Don't leave me in suspense!" I begged.

"Okay, okay. So there's a friend I made recently, who used to have some major issues. Her name is Starlight Glimmer and she's the most powerful unicorn mage I've ever met. She's as adept as I am, and she's only a unicorn. Er, no offense," said Twilight.

"None taken. Less polite, more detail," I demanded.

"Well, she tried to kill me once, and last week she came pretty close to destroying all of Equestria..."

I reacted out of pure shock. "Holy Celestia, Twilight! And you made this pony your friend? Wow. I guess you really are the Princess of Friendship," I said. As is often the case, I regretted the words as soon as they exited my stupid mouth. "No wait, I didn't mean..."

"No, no, it's okay," said Twilight, shaking her head. "It sounds dumb because it is dumb. But she matches the picture. Starlight is older than we are, but she looks fairly young and her bangs are just like ours. I just can't believe she would do something like this without a good reason, though! She spent last week with us in Ponyville, and it really seemed like she'd learned to let go of all the hate inside of her."

I sighed. "Well, the damage was done two days ago. Does that fit?"

Twilight winced. "It might. She left Ponyville three days ago to take care of what she said was 'unfinished business'. We all assumed she was headed back to this little village called 'Our Town' to continue making amends with the ponies she used to govern," said Twilight. "I just don't want to believe it. I really thought she had changed."

"Well, why would she come after me?" I asked. "I mean, it's nice you're my friend and all, but we don't really know each other that well."

"She knows you're a friend of mine. She was here in Canterlot spying on me the last two times I came to visit you. She might be using you to get to me... but that still makes no sense. She left on such good terms with all of us," said Twilight, with her muzzle scrunched up. She bit at her lower lip, and her eyes started darting back and forth as though she were reading an invisible book right in front of her face. "Oh, horsefeathers," she murmured, and her cheeks paled.

"Spill it, Twilight," I said. I suppose I was getting a little bossy, but I was tired of all the suspense.

"Moondancer, something strange happened a little more than a week ago. Starlight Glimmer used a magic item called the Cutie Map to send us both back in time in an attempt to alter the past," she said. "Then she sent me back to the present alone, and I used the same spell to return to the past to confront her again. We did this over and over, and finally I forced her to come with me to the present to see how the changes she was making would destroy Equestria. That ended up changing her mind, so we fixed the past and everything returned to normal."

I furrowed my brow in frustration. This was, by far, the stupidest, most ridiculous story I had ever heard in my entire life. If this were any other pony, I would have stood up and trotted away right then. But this was Twilight Sparkle, my former lab partner, and she was as precise as I when it came to the details. So I thought carefully through what she was saying, and after a few moments I realized the implications.

"You think there might be a second Starlight Glimmer because of the time travel," I said.

Twilight nodded. "Bingo. Each time I returned to the past to stop her, she was there waiting for me, ready to change things again. But she remembered our previous encounters, which means the Cutie Map kept sending her back in time along with me: each time I went back many years, she went back only a few minutes. But the last time I cast the spell, Starlight Glimmer was already in the present with me..."

"So this 'Cutie Map' could have targeted a copy of Starlight Glimmer shortly before she followed you to the present, and sent that version of her back by only a few minutes?"

"Yes, exactly. I don't think the Cutie Map would make that kind of error, but it's entirely possible. I don't know why I didn't realize it sooner. The other Starlight Glimmer could have returned to the present right after we left the castle."

"And this second Starlight lady would still be evil, and tied for the most powerful unicorn in Equestria," I said, and groaned. "Well then. That's comforting."

"It is? Wait, you're being sarcastic," realized Twilight.

I chuckled. "You don't have me fooled, Princess," I said. "You're a real pony just like the rest of us." I stood up, re-bagged the photo, and tossed several bits on the table.

Twilight stood up. "Are we going to your lab?" she asked. Her eyes lit up like a Hearth's Warming tree, and I felt an instant kinship there.

"Just follow me," I teased. "I have something amazing to show you."

The First Experiment

As I walked Twilight to the edge of Canterlot, my mind was still buzzing from that crazy story she'd just told me.

"I'm not sure I fully understand what happened between you and this Starlight Glimmer pony," I said. "A few weeks ago, Lyra told me about that time travel debacle you went through last year..."

"Really? How did she find out about that?" said Twilight, not angry, but clearly surprised.

I chuckled. "I think your dragon friend blabbed to a bunch of ponies."

Twilight rolled her eyes. "Of course," she said. "It's okay, though. Even without Spike's shenanigans, I don't get much privacy anymore."

I picked up the pace to a canter, and Twilight kept in step. I kind of expected her to ask me to slow down. Maybe she was just as eager to get to my lab as I was.

"Anyway, I did some research on the topic," I continued, raising my voice in case she fell behind. "I don't have access to the Star Swirl Wing at the Royal Canterlot Library, but his public works claim that Neighvikov's self-consistency principle always holds: if you try to change the past, events will align to ensure that everything stays the same. That's what happened to you the first time, correct?"

"Yes, exactly," said Twilight. "That's probably why that particular spell I used only works one time per caster, and lets you to go back at most one week. It would be much too easy to violate consistency if you could use it multiple times."

I looked over my shoulder at my friend and slowed my pace back down to a trot. The conversation was starting to interest me more than our destination. "But then how was Starlight Glimmer able to change the past in a way that altered the present using that same spell? That's a direct causality violation. She'd have to reengineer the entire spell framework, wouldn't she?"

Twilight took a moment to catch her breath, and I slowed even further to a four-step walk. All of a sudden, I wasn't sure why I'd been running in the first place. Something about talking with Twilight had made me nervous, like I was going to mess up and say something wrong and lose her as a friend again. It was almost like I'd been running from her. I resolved to fight that instinct.

"You're right, and I'm not entirely sure," said Twilight, catching back up. "Some of it makes sense: the Cutie Map allowed Starlight to go further back in time than a single week, and even though I was able to recast the same spell multiple times, it did the same thing each time and was tied to her original invocation. She did use it once to take me to a different point in history, but we were observers disconnected from the setting so I believe that case was at best an illusionary projection rather than actual time travel. That means Starlight didn't need to break either the one-week restriction or the once-per-caster restriction which had been built into the spell's design. The only significant modification she made was to break the symmetry of time travel, and she told me last week that it was easier to do than she expected. Until I saw what the modified spell could do, I didn't think it was possible to change the past at all."

"I'm obviously out of my element since I haven't seen the spell in question, but that still seems like one hay of a magical coup," I said. "You said she was powerful, but adapting a spell that can break time? That's a little hard to swallow."

Twilight stopped right there on the sidewalk and and tugged on my shoulder, turning me to face her.

"Moondancer, please listen to me. I'm not exaggerating when I say Starlight Glimmer is a powerful mage," said Twilight, her voice hushed. "I'm an alicorn, and she can do things even I can't do. I realize it's highly unlikely that the pony in the image is actually her, even though she's our only suspect—"

"Agreed. We extrapolated an artefact of time travel to develop that hypothesis, and we aren't even certain how that sort of time travel works," I interjected.

"Right. Nonetheless, we can't afford to take that chance. I'm going to take steps to make sure you're safe and secure. I'll call in the Royal Guard, magical security measures, the whole nine yards. No, make that ten yards," said Twilight, without a hint of humor in her voice. "I won't risk having anything happen to you."

I felt color burn my cheeks. "Thanks," I said. "Anyway, the lab's right up there." I pointed to the metal building at the end of the street, and we walked up to it together.

"Ironically, I was planning to do more research on Star Swirl's writings for the same reasons you just described," said Twilight. "I guess now I have an even better reason to. I can get you access to the Library too, of course," she added, with a grin.

"Holy Celestia, having a princess for a friend is incredible," I said under my breath, then immediately felt bad. "Oh gosh. I hope you don't think that means I'm using you, or something. You're actually a really good friend in general, even without the perks. I mean, I would want to be your friend even if you were a complete nopony—no, wait, I'm not saying—"

Twilight placed a hoof to my muzzle and smiled, and her eyes shined. "It's okay! It's good you can admit I come with 'benefits'. If you were really trying to use me, then it wouldn't be bothering you."

I nodded. "Yeah. Yeah, I guess so," I said, and I felt much better.

The building was a one-storey windowless brick of shiny metal with fins on the roof. The only other obvious feature was a large door set into the long side of the building, facing a makeshift gravel path to the sidewalk. Next to the door was a small hole. Reaching the end of the path, I inserted my horn into the hole and used my telekinetic signature as the identification spell. A mechanism in the door clicked.

"Put your horn in," I instructed Twilight. "I might as well give you access now. Just try to use your tee-kay to push against the end of the hole, and it should add your signature to the access list."

Twilight blushed as she placed her horn in the hole. I wasn't sure why, so I assumed she thought it looked silly. Another click sounded. Then I opened the door.

"Allow me to give you the grand tour," I said, and led my friend into the lab before shutting the door behind us. "This is the workroom, which takes up most of the West side of the structure. There's not much here except my desk and a futon for when I'm tired, but I haven't slept here since the incident."

"I can't believe it's all metal in here! Those walls must be half a hoof thick at least," said Twilight. "Thank goodness for the air conditioning, though the floor is freezing? And it's glowing, which is also weird, but I guess the walls reflect enough to make it ambient."

"The floor's freezing because it isn't AC. It's refrigeration conducted directly through the walls. The test rooms can't have air go in or out, so we just built the whole place this way," I explained. "The floor glows because the basement is where all the power is routed, so I just have a magic light enchanted from beneath except in the test rooms, which stay dark. And in the basement it's the ceiling that glows instead of the floor, obviously. That door there goes to the basement, the other one to the bathroom, and the one on the far wall leads to the test chamber anteroom..."

"Wait, you built this facility?" said Twilight. "And your magilectric bill must be enormous! I mean, if you're cooling through the metal, you're fighting the sunlight outside as you try to cool the inside..."

"Oh, right. Yeah, the cost is astronomical, but I have a backer in Manehattan with deep pockets. We had to build this thing to precise specifications. I'm actually paying to have a current delivered directly from the castle," I explained.

"Ah. That explains the humming sound," said Twilight. "Though I didn't notice you turn anything on when we walked in."

"I didn't. It's always on. My experiments draw so much more power than the cooling system that the way we control the temperature and lights is almost an afterthought," I explained. "It costs more to turn it on and off than it does to keep it pumping in. I'm pulling a little more than half a meg."

Twilight froze, then laughed. "Sorry, I must have been distracted. For a moment there I thought you said you were pulling in half a million horsepower."

"I did," I said.

"What?!" said Twilight, as her jaw hit the floor (metaphorically speaking). "That's crazy! Princess Celestia lets you draw that kind of power?"

I shrugged. "For enough bits she does. I had to clear some of the research parameters with the Court, of course. Mainly they needed to see evidence that I wasn't storing the energy for later use, which is easy enough because we have no magilectric capacitors in the system and there isn't a lot of flux in the power juncture they set up where the line splits off. Upstream, I mean."

Twilight leaned in close, as though we could have been overheard even though we were all alone in a giant metal box. "Moondancer, what in Equestria are you researching?" she whispered, her eyes focused directly on mine.

I grinned. "Antimatter," I said.

Twilight Sparkle squealed like a schoolfilly. I thought it was kind of adorable, though that's a pretty weird thing to think about a friend.

"So you're running a bunch of enormous bangbox experiments right here!" she said.

"Nope," I said, still smiling. "Better. I'm running long-term experiments."

"Oh! How do you contain the particles?" she asked.

"Not particles. Macroscopic quantities," I said.

Twilight's face changed from thrilled to horrified in a split-second. "MOONDANCER! We have to shut it down now!" she said, grabbing me by the shoulders.

I pushed her back, a little miffed by the reaction. "It's okay, Twilight."

"ButtheamountofenergyfromamacroscopicantimatterexperimentcouldlevelhalfofCanterlot!" she said, all in one large breath.

"I thought you might jump to that conclusion," I sighed. "No capacitors, Twilight. Do the math."

Twilight paused for a moment, and looked up at the ceiling as the gears turned in her head. "Okay... I guess it's not that bad. With that kind of input, in the worst case you'd have an explosion worth half a million horses. But you could still kill yourself and blow up a large portion of this structure," she warned.

"Nope. Take a look," I said, leading her to my desk. I pulled some schematics out of one of the drawers. "I found a way to create an energy field that can change matter into antimatter and vice versa. Large quantities of it. Megagrams worth, even. The matter and antimatter can even exchange kinetic energy between the field without colliding. The field is only permeable to light and gravity."

"That's incredibly impressive, but it's still impossible," she said, looking over the design. "You're not pulling in a fraction of the energy necessary to produce that kind of a potential energy imbalance."

"Exactly. That's because the field is absolute. Anything that would collapse the field automatically reverts the material inside of it to its previous state," I pointed out. "The field's integrity and the change in state are the same thing. I tested it out on particles and individual molecules for proof of concept. This is the first scale-up."

"This is one heck of a scale-up from molecules," said Twilight, with a whistle. "But you must be right. You don't have enough energy to cause a breach, so whatever method you're using... it has to be totally foalproof."

"Simple conservation of energy," I grinned, feeling a swelling of pride. "Pretty cool, huh?"

Twilight squealed again, and she actually pronked in place. I've never seen a pony so giddy before.

"Oh, Moonie, this is amazing! We can witness the macroscopic properties of antimatter for the first time! It's, it's... this is a historic event in scientific progress! What all have you done so far?" she asked, and finally stopped her bouncing.

Moonie? Eh, whatever. I decided to let that one slide.

"Nothing. The damage to the lab happened right before the first test run," I said. "Then I caught that mare on camera, and immediately contacted you. Although technically, the fields are always up inside the experiment chambers, so I've looked at small amounts of data already. Nothing really interesting, though."

Twilight Sparkle's muzzle twitched and her eyes widened. "Moondancer, if I help you with the security and research access... Could I maybe assist you a little bit with the experiments...?" she whispered, her lower lip quivering.

"I'd love to have you. If you're not too busy?" I said.

Twilight grinned from ear to ear. "YES! I mean, no, I'm not too busy! I'll go on vacation starting now, and restrict communication to emergencies and visits from friends," she said. "I might get interrupted if there's something important I need to take care of, but I should be able to stay up here with you most of the time, for the next few weeks at least."

"I can't believe I'm saying this, but I think this experiment is going to be even more fun with somepony to share it with," I admitted. "I'd invite some of our other friends, but let's face it: you're the only pony I know who can fully appreciate my work. Alright, what's next. The basement is where the current gets pumped in from, which is boring, and I'm going to guess you've seen a bathroom before. So let me show you the test chambers."

I led Twilight into the anteroom. It was a small room with five doors, not counting the one we came in: four on the opposite wall, and the fifth on the side. One of the metal doors on the opposite wall was missing, and fragments of metal door littered the area.

"Oh wow. You weren't kidding," said Twilight. "Is this all the damage?"

"Yeah. I haven't touched the pieces, just step carefully. Initial examination suggests it was deep-frozen and shattered from the inside of experiment room two with a heavy kick," I explained. "I didn't have the nerve to stay long enough to look for clues. I basically set up the camera outside and got the buck out of here."

"You said room two... are you numbering from right to left?" asked Twilight.

"No, I started from zero," I answered. "Oh, and the side door there is a second entry to the bathroom. Anyway, you can see roughly what the interior of the other three rooms looks like from this one. The field isn't up here, though. A failsafe turned off the field to chamber two once the structural integrity of its door was compromised." We stepped carefully around the debris and into the tiny chamber. There was barely enough room for two ponies to stand comfortably. We were awkwardly close, but I felt surprisingly comfortable with Twilight by my side.

The chamber was barren, with walls of smooth steel. The exception was an array of plastic slats affixed to the wall opposite what remained of the door.

"This must be the detection equipment?" said Twilight. "Looks sophisticated. I don't see the camera. And the lighting is off?"

"There isn't one. Mechanical cameras need too much light, and electrical ones get disrupted by the field. In my initial experiments on the smaller scale, photos were blurry and video too grainy to make anything out. That's why none of the experiment rooms have lighting in them. The field muffles audio, as well."

"I thought you said you were measuring light interaction?" asked Twilight.

"Low-energy light seems to come through okay—radio and the like, and these detectors are almost like cameras for those frequencies," I explained. "I'm sure you realize that each room is a Fawnaday cage, which protects the field from any outside electromagnetic influence. That's also important because of the charge symmetry of antimatter, but again you already know all this."

"It's okay, I like hearing you explain it," she insisted. A little weird, but fine by me. Talking out knowledge helps to solidify it, and this was much better than talking to myself. The experience of sharing knowledge with a friend was strangely gratifying.

"Anyway, that's still not the real payoff. Most of the data comes from changes in the strength of the containment field itself. It worked perfectly in the small-scale, but it's been finicky at this level. I really should have predicted that. I'm not trying for a vacuum, so all three sealed rooms are essentially filled with antimatter air as we speak," I said.

"Wow," whispered Twilight. "That's so crazy. So much potential energy that isn't actually potential energy, mere inches from us. Are you sure leaving this on all the time is really a good idea?"

"I'm not kidding, it takes a ton of draw to turn it off and on. I'd be offline for weeks at a time if I didn't keep the fields on," I explained. "I'll open one of the rooms so you can see a working array, but I don't open them casually. Every time one of these four doors—er, three, now—opens up, it causes a power drain on the whole system. If two doors were to be opened at the same time, it would kill the power completely. The doors have automatic locks with an ninety minute cooldown to prevent that. In order to open one door, you have to shut the currently open one—if one exists—and wait. Except for the broken one, because there's no field there anymore."

"If the other doors locked down, that might explain why the vandalism was confined to a single room," said Twilight, as she walked back to the entryway and examined its hinges. "Interesting. Hay, Moondancer, come take a look at this." I walked up behind her to see what she was pointing at. One of the metal hinges was bent at an odd angle. It looked like it had been torn partway off.

"The force of the kick must have damaged it," I said. Twilight raised a brow and said nothing, so I looked again. "No, wait. It's twisted, not shattered like the rest of the door. But the force shattered the entire door, so not enough of the energy would have remained to provide the torque necessary to twist the hinge..."

"Unless the door was all the way open when it was kicked," Twilight said, with a smug look plastered across her muzzle. A forgivable one, at least. It was a valid deduction.

I pursed my lips in thought and adjusted my glasses. "Clever. That's actually an unfortunate datum, though. If Starlight, or whoever, had done this from inside the room like I'd originally assumed, it probably would have indicated they had no idea what they were doing," I said. "You'd have to be suicidal to try to break the antimatter field, not to mention ignorant enough to think it was possible in the first place. So the fact that they smashed the door from the outside while it was open doesn't really tell us anything useful."

"True. But at least we're narrowing down what happened," said Twilight. "I think we can move the fragments to the corner of the anteroom, though. It looks like the door shattered in a single buck, and it was undoubtedly fragile enough that it didn't deform on impact to leave a hoof impression."

"Yeah, I was thinking that too, but it's good to have a second opinion. Well, before we go get the Royal Guard or whatever ideas you have for locking this place down, let me show you one of the active rooms," I said, stepping over the door shrapnel again and walking to room zero. "You can experience the field discharge. It's kind of neat."

Twilight stepped behind me, and I paused. "Hay, why don't you do the honors?" I asked, pointing her to the door. She made a little squeaking sound and hopped up, then her horn lit up and a look of confusion crossed her face.

"I can't grab the handle?" she said.

"Magic is nullified in close proximity to the fields. You need to do it by hoof," I explained. "Although it is possible to cast magic into the chamber from the basement where the fields originate, but even then only passive magic—not teleportation or telekinesis."

Twilight Sparkle reached out and held onto the handle with a hoof. "Right, of course. If the fields didn't negate magic, you could teleport the antimatter out, which would invalidate the conservation law," she said. "Okay, here goes..." Twilight winced and tugged at the door, then tugged harder and it finally opened. There was a soft, staticky popping sound, a familiar smell of ozone, and a gentle whoosh of warm air emanating from the room. That seemed very strange to me, because there shouldn't have been an air pressure or a temperature differential.

However, those data weren't what drew my immediate attention. Even though it was dark in the room because the chambers were unlit, I could clearly make out an object resting on the floor.

"What the hay is that?" I said.

Twilight turned on her horn, but the light fizzled when she tried to lean her head inside, so she pulled it back out to provide better illumination. On the floor of the empty room lay some kind of dark fabric.

"Hold that light there. I'll go grab it," I said.

"Wait! Are you sure it's safe?" asked Twilight.

"Yeah, positive," I said, exaggerating the truth a little. I stepped halfway into the room and felt an electric tingling across my pelt. I reached out and touched the fabric and felt a slight static discharge. I grunted.

"Moondancer! Are you okay?" asked Twilight.

"Yeah, just a static shock. But this fabric is, like, insubstantial somehow? It's passing through itself as I grip it and I can't pick it up—no, wait, I think I've got it now," I said. After a couple of squeezes it had entered my hoof. I stepped back and tugged at it, and it started to unroll. It was the strangest thing I'd ever seen in my life: the fabric seemed to be stuck in the area it was resting in, as though it were trapped in a gelatin mold, and I had to tug it free into the open air around it. It again seemed to pass through itself as I pulled on it, but one last tug yanked it up into my hooves. Now it looked and behaved like a perfectly normal...

"Dress?" I said.

"It's a dress," repeated Twilight, just in case that still wasn't clear. Even after we'd both said it, it still seemed unreal. It looked like a formal gown of some sort. The fabric was very soft.

"Did you see the way it was stuck there in space?" I asked her, still reeling from the experience. "And it seemed to pass right through itself, like a manifold in extra dimensions. But now it just looks and feels like an ordinary piece of clothing."

"I noticed that too. Was it made of antimatter?" she asked.

"It would need to be normal matter when the door is open, even though the field is still active. Maybe what we saw was just a weird visual effect caused by the field acting on normal matter, or something," I pondered aloud. Now fully out of the room, I used my magic to levitate and examine the dress. It was absolutely stunning: a ballroom gown in deep purples and midnight blues, spangled across the hemline with tiny diamonds and wisps of silver. "I'm no expert, but this thing looks really expensive—for lack of anything more relevant to note."

"Hmm. It looks a little familiar. May I?" asked Twilight. She levitated it from me and looked around inside of it for a moment. "Ah, there's the mark! I knew it. This is one of Rarity's designs. It's probably from her Canterlot store," she said. "Wow, Rarity is going to totally freak when she finds out one of her dresses became antimatter! She'll probably charge a fortune for it. I should convince her to donate it to a museum..." she babbled.

"Twilight, focus. What the hay is one of your friend's dresses doing in my test chamber?" I asked.

Twilight took a deep breath. "It must be Starlight Glimmer. This is too many coincidences in a row," she said. "She's the only pony I can think of who has a connection with you, me, and Rarity. She must have left it here as some kind of warning or something, after she broke the door..."

"Maybe she left it shortly before she broke the door. I didn't open any of the rooms around the time it happened."

"Then we should check the other rooms," suggested Twilight.

"Not right after we opened room zero," I said, and then I closed the door to room zero to punctuate the point. "Remember, we need to let the power stabilize before we open another door. Every time we open a door, it's an experiment," I explained.

"Right, sorry. Actually, now that you mention it, maybe we should wait before doing anything with rooms one and three," said Twilight. "We already have a preponderance of data that we don't understand."

"Agreed. Methodical examination needs to trump curiosity at this point," I said. "I guess we can open room one tomorrow and room three the next day. But in the meantime, we need to secure the facility. If Starlight Glimmer can sneak past the lock, she could completely trash the place next time. She might even have performed her own experiments using the facilities, in which case we'd be working under a substantial knowledge deficit. If she's as smart as you suggest, she could have figured out most of the basics of my research from the documents I keep here."

"That's disturbing to consider, but you're right. We need to assume she knows more about your antimatter experiments than either one of us," said Twilight. "Alright, here's the plan..."

For a moment I felt irked at Twilight taking the reins like that, but then I smiled. It was actually a little inspiring to watch her spring into action. I wasn't about to tell her that, but still.

"...I'll go get a guard detail. Two guards on the facility, twenty-four hours. Another two on your place," she said.

"Do you think I really need to be guarded?" I asked. This whole business was starting to feel weighty.

"Yes, but now that I think about it, we should make them both plainpelts. They can recon your house while you stay at my old place," she said. "My place is already warded and in a high-traffic part of town where somepony trying to break in would likely be noticed."

"I should sleep there tonight, then," I said.

"Oh, right," said Twilight, blushing. "Well, yeah. You can sleep in my bed there, the sheets are clean and everything. Maybe a little dusty is all. I can, um, stay at the castle."

I've already been sleeping there once or twice a week, I thought to myself, but I bit my tongue.

Twilight scrunched up her muzzle. "Actually... I'll have at least one guard watch my place too, just to be extra safe. And the entire Royal Guard will be warned that Starlight Glimmer herself may be in danger, so they'll keep a lookout for her safety as well as ours."

"Sounds good. I may head to your place now, actually. There are some books on physics I want to review to see if something might explain the odd behavior of this dress," I said.

"Well, keep in mind this is uncharted territory," said Twilight. "We really don't know what to expect from large-scale quantities of antimatter, so it's okay if you don't. But I agree with you that research is the right step. I'm going to pick up some books from the Royal Library while I'm setting up the guard. She may be dangerous, but once the entire Royal Guard has been alerted, we should pretty much be Starlight-proof."

I breathed a sigh of relief. "I guess I have nothing to worry about, then," I said, with a wry chuckle.

I still felt worried, though.

Twilight had a brave face on, but I could tell she was worried too.

Missing Pages

Twilight stayed with me at the lab while I wrote up our observations, and then she headed to the castle to alert the Royal Guard. I was eager to go back to her place and start my own research. I took the dress with me, just in case I thought of any tests to perform on it.

After arriving at Twilight's place, I spent several hours poring over textbooks in magic field theory and quantum mechanics. It was starting to get dark outside when the front door opened up. Twilight Sparkle was standing there, wearing a fancy set of saddlebags. Accompanying her was a nightwing guardstallion.

"Thank you, Nightcap," Twilight said to him. He silently nodded to us, then turned and shut the door. I could see him through the window. He remained stationed at the entrance to guard us.

"I've never seen a nightwing up close before," I said. "Interesting."

"They're cute, don't you think?" said Twilight, with a giggle. "Especially the ears."

"Cute? Ah, I guess," I responded, with a bit of a blush. "I don't really have much of an eye for ponies."

"I don't have, like, a thing for them, or anything," Twilight nervously insisted. "I used to have a bit of a thing for guards in general, but I grew out of it. I doubt I'd have enough in common with a guard to make it a realistic fantasy."

"I have nothing to contribute to this conversation. I've never even had a special somepony," I said, with a sardonic chuckle.

"Me either!" said Twilight in a hushed but energetic voice. "It's so weird! Here I am: a princess, a polymath, I go on weekly adventures, and I have an active social life. And yet, I've never been kissed."

A painfully awkward silence followed.

"Anyway," I said, mercifully breaking the quiet, "we should probably touch base on our research. I've been studying the physics since I got here. I'm low on insights, though, so maybe you should start?"

"Sure. I brought some books with me. This probably goes without saying, but these are not to leave this building unless they're being transported directly back to the library," she said. Twilight set her saddlebags down and pulled out several ancient-looking tomes.

"Holy Moon above," I gasped, feeling my pulse quicken. "As long as those are here, I probably won't leave either!"

Twilight laughed brightly. "I know the feeling! I'm afraid they're not as interesting as you might hope, though. I brought them from the Star Swirl Wing because each one contained offhoof references to temporal effects of thaumaturgy, but none of them are directly related to the topic. So far I've only found one interesting passage," she said. Twilight trotted over to a couch with a levitated book in tow, then sat and patted the cushion beside her with a hoof.

For a moment I felt like I was being beckoned like a dog, and it irritated me. I'm not sure what it was about other ponies' behavior that always seemed to set me off. I knew Twilight wasn't trying to be rude, but I felt very uncomfortable. I frowned for a moment, then shook off the feeling and walked over to sit beside her. It was clear from her face that she noticed my discomfort, but she said nothing.

"Um, so, here's what I wanted to show you," she said, and flipped to a left-hoof page in the book. A strip at the bottom of the page had been ripped clean off, and several pages which followed had been torn from the book entirely. The page read:

geodesics of spacetime curved by relativistic mass charge. Spatial transport via wormhole, such as standard teleportation magic, limits velocity to lightspeed. These three facts imply that causality violations do not generally arise in nature without magical intervention. There are two edge cases where causality violations might inadvertently occur: when teleportation wormholes are cross-linked, or when enormous gravitational masses are moving at close proximity and at relativistic velocities. As yet, there is no known way to cross-link the effects of teleportation magic, nor do we have access to gravitational masses anywhere near the magnitude required to create a causality violation. Because of this, the only known way for matter or information to travel backwards through time (hereafter referred to as 'time travel') is by means of magical spells designed specifically for that purpose.

Star Swirl the Bearded has identified three forms of time travel which are potentially accessible by thaumaturgical means. These are referred to as time travel of the first form, the second form, and the third form.

Time travel of the first form includes any kind of time travel that is forced to obey Neighvikov's Principle of Temporal Self-Consistency (as discussed in elementary texts). It is the only kind of time travel which is not proscribed by law. Spells which allow time travel of the first form are reasonably complex, but a practiced mage should have little difficulty. Since the magic follows Neighvikov's Principle, it does not allow causality violation. Consequently, such spells cannot be used to change the past or create any sort of temporal disjunction. The clever reader will, however, recognize the inherent potential of such magic to create beneficial ontological paradoxes.

Time travel of the second form involves a second dimension of time which passes through and intersects the first via the inertial frame of reference of the traveller (more technically, through all travellers who will ever exist). This allows a single 'master' timestream be altered probabilistically. Changes to this timestream affect the likelihood of all future events across Equestria, and in fact, across our entire universe (i.e. 'world dimension', to the laypony). This kind of time travel is proscribed except by Royal Decree, and to date no ponies other than Star Swirl the Bearded have ever been granted permission.

It is known by a few scholars close to Star Swirl that he has made extensive use of this form of time travel in order to secure a bright future for Equestria. In the parlance of the common pony, this form of time travel gives rise to the phenomenon known as 'prophecy'. Most prophecy is necessarily vague in order to achieve self-consistency. If not vague enough, prophecy leads to a contradiction that spontaneously alters the timestream, falsifying itself. The nature of determining how to make a prophecy self-consistent is well-known to Star Swirl the Bearded, but his methodology is a carefully guarded secret. However, it is generally assumed to require the use of time travel of the first form in conjunction with scrying magics.

Spells allowing for time travel of the second form are no more inherently complex than those allowing time travel of the first form; but unlike spells of the first form, they require a gargantuan source of mana. Centuries after Star Swirl's disappearance from Equestria, the only current source capable of channeling a sufficient amount of mana is the Tree of Harmony, and communing with the Tree is a task beyond the skill of all but the most talented and practiced mages. This is highly fortunate. Spells which allow time travel of the first form can easily be altered to allow time travel of the second form, and without such a natural restriction, all time travel spells would need to be proscribed by law. Were that the case, I would not be writing this chapter (naturally). Even knowledge of the existence of time travel of the second form is tightly restricted to those with Celestial approval, and so any books which bear this text must likewise be restricted.

Time travel of the third form is proscribed absolutely, as per Equestrian law on universal

I furrowed my brow as I attempted to parse the words. "I'm not sure I follow what 'second dimension of time' implies."

"I'm not entirely certain myself, but I suspect it just means casters like Star Swirl can manipulate the dimension of time that we're familiar with while moving through time in a different way. As Star Swirl manipulates events from outside the timestream, our future changes. This would match what Starlight Glimmer was trying to do."

"Wait, I think I get it. The only thing that matters in the end are the last changes that occurred from the traveller's perspective," I said. "The fact that the final action Starlight Glimmer took from her frame of reference was to leave the past intact, meant that Equestria's future would return to normal. It effectively erased all the meddling she had done in her previous attempts."

"Exactly. Put another way, her attempts to change the present occurred in a definite sequence that she experienced, even though each individual step of that sequence took place at the exact same time from Equestria's frame of reference," said Twilight. "So it's kind of like there's a second flow of time she's travelling through, even though I'm not sure 'dimension' is an accurate characterization for the idea."

"Right, but that doesn't explain how she was able to cast the modified spell. You said she cast it using a device called the Cutie Map, but according to this the spell would have required the Tree of Harmony," I pointed out. "This may be an old text, but I doubt any mana source more powerful than the Tree of Harmony exists today, either."

"That's easy enough to explain. The Cutie Map is an extension of the Tree of Harmony," said Twilight.

"That makes sense, then. But what's up with the missing pages? I'd assume it was some kind of accidental damage if it weren't for the missing strip at the bottom of this page," I said, pointing with a hoof. "It looks like the book has been intentionally damaged."

Twilight took a deep breath. "I think this information was willfully destroyed or censored, Moondancer."

"By who? Starlight Glimmer?" I asked.

Twilight looked away for a moment.

"Twilight, are you okay? What's going on?" I tried to say it gently. I hoped it sounded like I was concerned. I wasn't particularly good at this kind of pony relations thing, and I felt completely out of my element.

Twilight turned toward me and took my hoof in hers. "Look, you've shared some amazing research with me, and that took a lot of trust," she said. "Can I trust you to keep some things in confidence in return?"

She sounded so vulnerable all of a sudden. I lost my words, so I simply nodded.

Twilight sighed. "I'm pretty sure it came from the top down."

"You mean Princess Celestia," I said. "Okay. Why would that need to be some kind of secret?"

Twilight looked a bit taken aback. "Well, it just seems wrong to me. For Celestia to make a form of magic illegal is fine, but to cover up knowledge? What's next, blocking the road to scientific inquiry? I don't want to believe she would do something like this."

I bit my lower lip. "I don't mean this in a bad way, but maybe it's not so wrong for her to censor something that might destroy Equestria, Twilight."

"I agree," said Twilight. "But to censor it from academic texts that are already under lock and key? Somepony out there has to be qualified to understand it."

"She probably has unabridged copies somewhere."

"She never told me about them!" said Twilight. She seemed very upset, and then she sighed again and buried her face in her hooves.

It all seemed rather self-centered, but I didn't really know what her deal was, and she was clearly hurting. I realized I needed to be a friend, and I figured that meant not judging her. So I scooted over a little and put my foreleg around her.

"I must sound so full of myself," Twilight murmured into her legs.

"Twi, it's okay," I said, momentarily distracted in wondering whether 'Twi' was an appropriate moniker after it accidentally slipped past my muzzle. I gently stroked her back in a circular motion. "I don't know why this is important to you, but Celestia probably has her reasons."

Twilight lifted her face up. She wasn't crying or anything, but her face was a mask of stress and worry. "You don't understand what it's been like," she said.

"Don't? I probably can't understand. But why not tell me anyway? I already agreed to keep this in confidence," I said. "What's Celestia really like? Is she hard on you all the time, or something?"

Twilight shook her head. "No, not at all. She isn't even my mentor anymore, now that I'm a princess. But more and more my talks with her are so... heavy," she said.

"You talked to her while you were setting up the guard, didn't you?" I asked.

Twilight nodded. "I didn't reveal details of your research, I swear," she said. "She only knows what you've told the Court, and the fact that you might be a target."

"I guess it'd be okay if you did," I lied. "Some of what I'm doing is supposed to be a secret, but... it's complicated. Anyway, that doesn't matter right now. You were saying something about talking with Celestia?"

Twilight paused for a few moments as she stared at the floor. Then she sat up a little and turned to face me.

"Are you familiar with the ethical trolley problem?" she asked me.

"Of course. A Manehattan trolley is going to kill five ponies unless you throw a switch, in which case it will kill one. So you throw the switch unless you're an idiot," I say. "I don't understand where the ethical conundrum part lies, to be honest. Seems cut and dried."

Twilight chuckled, and it felt good to see her crack a smile. "Well, yeah. I'm largely a utilitarian and I agree with you, but for some ponies the 'active' thing makes it bad. But there are much harder variants, like, where you have to actually murder somepony to save other ponies, like shoving a heavily-armored pony in the way of the trolley to stop it."

I shrugged. "In that case I'm going to be guilty of murder, but I'll still do it as long as it's a sure thing, which is fortunately next to impossible. So the cost goes up to one life lost and one pony in jail, which is me, and that has less weight than the five lives I'm saving."

"Logical, and for the most part I agree in principle. But when the time comes to react in a real-world situation?"

"Well, I'd probably freeze up. I've never had to face an unwinnable scenario of that magnitude, and I know I'd feel guilty even if I did the right thing," I admitted.

Twilight nodded. "I've had to face those kinds of scenarios in real life, Moondancer. My friends have had to face them with me. If you're my friend, you might be forced to someday, too."

I huffed. "If you think I'm afraid to be your friend, you're crazy. I mean, I don't really want to get drawn into these insane adventures I've heard about where I'll have to murder some random pony by tossing them in front of a rail car or whatever, but I'd do it if I had to. Now is that what this is all about? Are you afraid of cursing me with your friendship or something? I mean, earlier today I was worried about the perks of being your friend..."

Twilight shook her head. "It's not that. It's Princess Celestia," she said. "Ever since my coronation, she's been... kind of intense."

"Is she trying to interfere with your friendships or something?"

"No, nothing like that. She's just so dead serious when we're alone, now. Please don't ever repeat this, but... now that I'm a princess, Celestia says I need to be ready and willing to do anything for 'my little ponies'. Emphasis hers."

"You mean, die for them, or something?" I asked.

"I wish that was all she meant—that would be easy!" said Twilight, shaking her head. "Of course I'd die for my friends, not to mention all of Equestria. The problem is just the opposite. She's been trying to convince me that I need to start valuing my life above the lives of other ponies. Someday, I might need to order somepony to their death in the name of the greater good. Moondancer, I'm barely twenty-five years old! I only discovered true friendship less than three years ago. I can't deal with this level of responsibility."

I didn't really know what to say, so I just leaned in and hugged her. "Well, you shouldn't have to," I said. "Princess Celestia got by without you or her sister for a thousand years. I'm pretty sure her paranoia isn't justified."

Twilight leaned into the hug. "She's been delaying things for a thousand years, Moondancer. She's been waiting for Luna to return and for me to appear," she whispered. "At Star Swirl's direction, all sorts of major catastrophes have been delayed until now. That's why we've had all these challenges lately: Sombra's return, Discord's Seeds of Disharmony, the changeling invasion..."

"Look, Twilight. If there's anything I know about you, it's that you have friends that will always be there when you need them," I said. "And I can't believe I'm saying this, but I'm one of them, and even though I'm new to this whole 'friendship' business I would probably take a spear to the heart for you, or for all of Equestria if it came to that. We're all on the same side, together. Princess Celestia probably doesn't remember what it's like to be young and confused. She needs to lighten up and lay off."

Twilight nodded and sniffed, wiping a wet eye. "Yeah. You know, I still see her like she's some perfect goddess or something, but I know she's a pony just like you or me," she said. "I need to tell her that this has been bothering me. Thanks for helping me see that."

I smiled. Did I just help somepony with a friendship problem, I wondered? Interesting. "No problem, Twilight. That's what friends are for. Or, so I've been told," I joked, poking her in the ribs and forcing a giggle out of her.

"Okay, okay. I'll need to ask Celestia about time travel of the third form sometime soon, so I'll talk to her about the pressure then. Just... not for a few days. I need more time to relax before facing her again. Besides, whatever the third form is, it isn't likely related to the first two, so it won't provide us with any data on how Starlight Glimmer may have been duplicated," she said.

"I agree. It's clear she modified that first form spell to a second form spell. If Star Swirl was the only pony permitted to use that kind of magic, we're not going to find other examples in the archives," I said. "How well do you remember of the spell?"

"Not well enough, I'm afraid. It was too complicated to cast by memory since there wasn't nearly enough time to memorize it, so I had to cast it from the same scroll Starlight Glimmer used, and the Cutie Map destroyed the scroll after we finally fixed everything. I'm pretty sure I could modify the original spell in the same way she did, but I have no desire to muck around with Equestria's past. Star Swirl undoubtedly set everything up as perfectly as possible, so any changes I might make would create a mess," said Twilight. "Anyway, that's all I've found so far. Do you have any new ideas?"

"Not many," I said. "How familiar with quantum theory are you?"

"I'm a little rusty," said Twilight. "I know the basics, but feel free to fill me in on the details."

"Okay. Well, I was thinking about how the dress seemed to pass through itself when I peeled it out of that shape it was stuck in," I said. "So I've been reviewing work related to CPT symmetry. You know what that means, yes?"

"I think it means that if you flip the electric Charge by going from matter to antimatter, everything stays the same as long as you also flip the Parity—meaning everything gets flipped to its mirror-image in space—and reverse the direction of Time. Is that right?"

"More or less. Essentially, the combined symmetries of electric charge, mirror-image parity, and the flow of time, are always preserved," I explained. "Antimatter has opposite electric charges: anti-protons are negative and anti-electrons (also called positrons) are positive. Since CPT symmetry is always preserved, if you do an experiment with antimatter that moves counter-clockwise, it will look exactly like a time-reversed movie of an experiment using matter moving clockwise."

"But it isn't actually like the antimatter is going backwards through time, is it?" asked Twilight.

I shook my head. "No. That's only true at the quantum level with virtual particles. When particle-antiparticle pairs spontaneously pop into being and annihilate each other, it literally is like a single particle moving forward in time, then turning into its antiparticle and moving backwards through time to the origin. It's a true closed timelike curve where no causality violation can occur," I said. "It works just like Neighvikov's Principle, in other words. If a virtual particle ever interacts with another particle, it isn't virtual anymore, and so the loop through time can't happen in the first place."

"It's like nature self-censoring by only allowing single-particle time loops that are stable," said Twilight. "But you're saying that doesn't happen if the particles interact?"

"Right. As you know, entropy—the flow of energy from ordered forms to chaotic forms—is the arrow of time. It's why time has a direction: why we can remember the past, but not the future. Entropy is a result of quantum randomness naturally producing more disordered states than ordered states."

"So, anything macroscopic only moves through time in a single direction, regardless as to whether or not it's made from matter or antimatter, yes?" asked Twilight.

"Exactly. But CPT symmetry also has implications that affect experiments beyond virtual particles. For one, because CPT symmetry is mathematically inviolable, this means anything that seems to break combined CP symmetry must have a matching violation in T symmetry. For example, some particles can transform into their corresponding antiparticles, but the probability is not symmetrical," I continued. "This is part of the underlying reason the universe is filled with lots of matter and very little antimatter. Time moving forward is more likely to have matter in it, while time moving backwards is more likely to have antimatter. Well, that's not exactly true, but it's the general idea."

"Oh! That would explain why CP violations are often called violations of T symmetry, because they're effectively the same thing," beamed Twilight. "If you flip charge and parity, everything runs backwards—except for entropy, of course. So what's the parity violation that accounts for the fact that antimatter favors turning into normal matter as time moves forwards?"

"It has to do with the spin orientation of individual particles. It's kind of complicated, though, and not directly related to our problem. I was curious if there might have been a parity violation given the odd behavior of the dress when I tugged on it, because it was antimatter before we opened the door, which might count as a charge violation," I explained. "But there wasn't a charge violation when the phenomenon occurred. It was normal matter when I was pulling on it, so there would need to be a violation of time symmetry somewhere. And it's clearly a normal dress moving through time like any other hunk of matter."

Twilight narrowed her eyes in thought, then stood up and walked over to where the dress was resting over a chair. "I'd like to ask Rarity some questions, but she's busy in Ponyville this week. However, her Canterlot store manager Sassy Saddles might know if this particular dress came from the Canterlot Boutique," she said. "Hay, would you like to come along? It's a really nice store, and I can introduce you to Sassy."

I blushed a little and tugged at my ratty sweater. "I'm not exactly a fashion horse, so I'd never really set hoof in a place like that by myself," I said, then pressed my lips tightly together for a moment.

"Oh. Well, it's okay if you don't want to," said Twilight, and she headed for the door. She sounded a little disappointed, I thought.

This felt like an opportunity passing me by. I didn't want to go to a stupid dress store, but maybe with Twilight... maybe it would be interesting just because of her. It would be a challenge to not screw up in public in front of one of Twilight's other friends, assuming that's who this Sassy pony was. Turned out I was up for a challenge.

"Hold up, let me come with you," I shouted, just before Twilight shut the door.

Uncommon Scents

As we left the building, Nightcap stood at attention and saluted. I took a quick glance at his weirdo fuzzy ears. Maybe they were sort of cute? Eh, I didn't really know. If I were the type to get 'turned on' by other ponies, it'd be for their brains, not their bodies. The brain is the primary sexual organ, after all.

Twilight carefully carried the dress with her magic. I brought something with me as well.

"What's that?" asked Twilight, craning her head to see what I was holding on the other side of my body.

"Don't you remember?" I said, with a smirk. "It's that piñata stick from the party you threw for me. I don't know if you realized it, but at the time I was so angry I had half a mind to clock you with it! But I'm really glad things turned out the way they did." I raised it higher into the air, and for a moment I thought I saw Twilight wince.

"Oh. But why are you bringing it to the store?" she said.

I shrugged. "Paranoia, really. In a pinch, I know I'm better with magery; but on rare occasion a mace will do what a mana bolt can't. It's more accurate for moving targets, can more readily cause physical damage to inanimate objects, and could be used to block some kinds of magic."

Twilight looked very concerned, but the look quickly softened. "I hope it doesn't come to something like that, but you may have a point," she said. "You really might be in danger, Moondancer. I don't want to think about it, because I feel like it's my fault." She frowned with her eyes downcast.

I stopped walking and reached around her withers to pull her into a hug. "It's okay," I said. "A little danger is worth being your friend." I wasn't certain I actually felt that way, but it was stupid for Twilight to beat herself up over being my friend.

She smiled weirdly—shyness, perhaps?—and we continued our walk. "You should probably leave the stick inside the entrance, though," said Twilight, with a nervous chuckle. It's not like she'd needed to tell me, though. I was already worried about making her look bad in front of one of her other friends.

Canterlot Carousel was a quaint little lilac-colored two-storey building at the edge of the business district. I'd seen it before, and I'd heard that Twilight was involved in promoting one of the dresses. That's pretty much all I knew. It was evening now, and it looked like we'd arrived just in time. A tall, slender pony was flipping the sign from 'Open' to 'Closed'.

"Hay, Sassy Saddles," said Twilight. "Can my friend Moondancer and I come in and chat before you close up for good?"

Sassy Saddles smiled. Despite wearing heavy makeup, she was very pretty, and that was saying a lot because I wasn't attentive to those kinds of social details. Ironically, judging from the state of her horn, she didn't have a special somepony. It was common knowledge that unicorns who leave their horn with a sharp tip are single and looking, because there's no way they could be intimate with another pony without accidentally poking their eye out. Sassy's horn looked sharp enough to pierce ears with. I found it to be an unpalatable fashion, personally, not to mention tacky as wet hay. Not only was it garish advertising that made a pony look desperate, it was something of a public health hazard... as well as disturbingly reminiscent of the sorts of regrettable wartime soldiery images one can find in dusty history books. Sassy was already big-boned enough to vaguely resemble an emaciated stallion, so the horn wasn't helping any.

I wondered why I had to be so critical of everypony before I met them. I realized it was probably a defense mechanism from back when I was avoiding social situations. If I could shut somepony down right up front, I wouldn't need to be disappointed later. Old habits die hard, I thought.

"Pleased to meet you, Moondancer!" said Sassy Saddles. "Princess Twilight Sparkle and her friends are always welcome in Canterlot Carousel, even after hours." She led us inside and locked the door. I dropped my mace by the entrance.

"Thanks Sassy. Moondancer and I were wondering..." began Twilight.

"Oh, I can see! Darling, we simply must get you out of that itchy-looking navy sweater and alter this marvelous dress to fit you," Sassy said to me, to my immediate annoyance. "I might even be able to find some glasses frames more suited to your lovely muzzle..."

"Not why we're here," I said, in a voice that did nothing to hide my displeasure. On the bright side, I no longer cared about making a good first impression on Miss Saddles.

Her delicate face fell like a stone. "Oh... oh no, I've done it again," she said. "I'm so, so sorry. I'm such a foal..."

"It's okay, Sassy, it was an honest mistake," said Twilight, attempting a lightning-quick intervention. "You saw the dress, so naturally..."

I sighed. "It's fine. I know I don't look like much," I said, spitting the words out so we could move on.

Sassy's eyes widened. "Oh, goodness no! It's just the opposite," she said. "You're such a pretty young mare, but it's almost like you're hiding it."

I gritted my teeth and looked down at the floor. I hated being complimented, especially on my looks. She was right about one thing, though. I was hiding myself, because I didn't want to be noticed. But now that I have friends, maybe... maybe the idea was something I should learn to be okay with.

Twilight looked afraid to say anything, so I spoke up again. "Again, it's fine," I said, looking back up to Sassy Saddles. "You're right: I'm shy, and I hide my looks. And trying to offer me your time and assistance is generous. I'm new to being social with other ponies at all, though, and it's a little too soon for me to work on something like that." What an immense relief it felt to say all that! Even with the sweater on, I somehow felt naked and vulnerable; but it was okay. The honesty helped me feel like a 'real pony', meaning I no longer felt like I had to pretend to be a person in order to fit in. I cracked a genuine smile, and it was contagious. Sassy and Twilight smiled back at me.

"If you ever change your mind, or even if you just want to stop by and say hello, I'd love to get to know you better," said Sassy. I nodded, and at that moment I stopped hating her. It came with a price tag, however. While the socializing felt nice for the most part, this friendship thing was emotionally taxing to the point of affecting me physically. I was starting to feel very hungry. I'd have to raid Twilight's fridge later tonight. I wasn't surprised by this, however. As a perpetual student, you quickly learn that too much study or magic use can be physically draining. I was starting to realize that social encounters were no different, at least not for an introvert like me.

Twilight held the dress up to Sassy. "We found this dress... somewhere very strange," she said. "We're concerned somepony may have left it behind as a kind of threat directed at the two of us. When I saw Rarity's mark inside, I wondered if maybe it came from here?" Quick and to the point, I thought. I silently enjoyed Twilight's efficiency in those moments when it surfaced. Conversations are so rarely efficient.

"A threat? Oh my Stars!" gasped Sassy Saddles.

"It's kind of a secret, but the Royal Guard already knows," I said. "No need to worry."

Sassy nodded. "I won't tell a soul. Let me see," she said, taking the dress from Twilight as the aura around it swapped pale olive for Twilight's magenta. I was stunned, and resolved to stop prejudging ponies so much—I never would have pegged Sassy Saddles for a yellow. I'd always presumed ponies with auras similar to Celestia's would be stuck up, since the ones I'd met were, but Sassy was warm and giving. She set the dress on a dress form and examined it closely.

"Rarity's mark is in the collar," said Twilight. "I was pretty sure it was hers even before I looked."

"It's definitely her work, and we must have sold this one recently. I remember it distinctly because it's perfectly symmetrical, which is a departure from most of her recent works. Oddly enough, her mark is the right way around from within the lining, which is the opposite of the way she usually does it—generally you want to see the maker's mark from the top down. She's just adding variety, I suppose," said Sassy. "I don't remember selling this dress personally, but it must be from one of her last two shipments. There are two ponies who work for me here who might have sold it. Let me look in the back room to see if I can find the purchase order. I'll just be a moment." She trotted quickly into the back area, and Twilight turned to me.

"I'm sorry about that," Twilight whispered. "Sassy means well, but she's... a little insecure."

"It's fine. It forced me to admit something about myself I didn't want to face, and I actually feel better for it," I said, and smiled. "Maybe there really is something to this 'socializing' thing."

Twilight giggled. "I'm glad. And I think you're beautiful just as you are—if you're trying to hide it from me you've failed," she added.

My cheeks burned like fire. Fortunately, I was saved from my embarrassment by a whooping sound from the back area. Sassy Saddles came galloping back to us with something in tow. It was an identical copy of our dress.

"Oh!" said Twilight. "Well, I feel like an idiot. I didn't even stop to think Rarity might have made multiple copies."

Sassy shook her head. "I didn't know that she did! The shipment she sent me had only one dress like this. Rarity only does copies for special orders. Uniqueness is kind of her thing, and it's one of the major selling points of the shop," she said. "I'm surprised she made a second copy. I might need to take this one off floor rotation until I get confirmation from her, because I don't want to sell it as a unique garment if there's a second copy also intended for sale."

"So why would there be two copies?" I asked. "Maybe the one we found is a prototype?" I figured complicated dresses probably had those.

Sassy scrunched her muzzle up in thought, which was amusing to watch: for a mare, she has an awful lot of muzzle to scrunch. Then her eyes opened wide, and she grabbed a second dress form to place the dresses side by side. "Let's see if we can find anything unusual, then?" she asked.

"Sounds like a good idea. You probably know better than we do," said Twilight.

"Of course!" said Sassy. She probably didn't intend that to sound as egotistical as it sounded (at least to my ear). We watched as the resident dress expert examined both dresses. She compared every detail on the outside of the garments, then lifted up the hems to check for stitching. Several times, she appeared to be sniffing the dresses, which struck me as weird.

"They're almost exact duplicates, right down to the measurements, except that the one from the back room has the mark facing the normal way," she said. "Rarity must have made both, or else somepony out there is a master forger. The stitching is virtually identical, and the pattern is exactly the same. Even the tiny details in the ruching are identical. However, there's something very strange about the silk. Have either of you tried smelling the dress?"

Twilight's ears twitched for a moment. "Hmm. I guess we didn't think to," she said. "In retrospect, that was an oversight."

"Come over here. This is really interesting," she said, her eyes bright.

We both headed over and smelled each dress. Sassy's dress was just a little perfumey, probably from being in the store. Apart from that, I couldn't tell any difference.

"Do you mean the perfume from the store?" asked Twilight.

"I'm not getting anything other than the perfume scent, either," I said. "My olfactory capabilities must not be on par with yours, Sassy."

Sassy looked surprised for a moment. "Well, I do have a better sense of smell than most ponies, and the odor is very subtle. Under the perfume of the store dress there's a very, very slight fishy smell," she revealed. "It's too weak for most ponies to detect, although some of us can smell it when we sniff the fabric directly. The scent comes from bits of chrysalis that inadvertently become part of the silk. Now, there is a kind of high-end silk without the scent, but it's extremely pricey; and as I said, nopony actually notices the scent unless they try."

Twilight leaned in and smelled again. "Wow. I can't even tell it's there when I try," she admitted.

Sassy smiled and nodded. "This is exactly why the expensive silk is only used for special orders. Even then, most of those orders are from ponies who can't smell it themselves, but just want the best material available. Vanity is pricey."

"It's also stupid," I said, immediately regretting it. Open mouth, insert hoof. "Um, I'm sorry I said that," I added.

Sassy Saddles laughed. "Not at all! You're right, it is silly. Even though I can tell the difference, I wouldn't want the special silk myself, except maybe for a wedding dress if I decided to splurge for perfection; but profit is profit and we aim to please," she said. "Anyway, even if you can't smell the silk, take another sniff at the dress you brought in. Close your eyes and sniff right up against the silk portion of the dress. Then try to describe it," she said.

I shrugged. Twilight took another whiff of our dress, and then I followed suit. It felt ridiculous, but I closed my eyes and concentrated as best I could as I sniffed at the silk. It actually helped a little: I noticed something new.

"It's strangely sterile," I said. "It doesn't smell like much of anything."

Sassy Saddles nodded. "Yes, that's one important detail. It suggests that the silk used to make this is the very expensive kind. But there's another detail. Can you smell anything at all?"

Twilight took yet another sniff of the silk. "Wait, I think I can. Is it naphthalene?" she said.

I thought Sassy momentarily looked like a deer frozen in a flashlight, and then I wondered if that was racist. "I'm afraid I have no idea what that is," Sassy finally said.

"Primary ingredient in low-grade mothballs," I offered. "I didn't smell it, though. I probably don't have a nose for this sort of thing."

Sassy nodded. "That's not bad, Twilight. It's a little reminiscent of mothballs, yes. But it isn't mothballs. It's a distinctive but odd smell, and frankly, I've never smelled anything quite like it before," she said. "What's more, that smell is only in the silk and not in the rest of the dress, so it isn't something the dress absorbed. That's because the cotton would absorb scents more readily than the silk. I don't know what the scent is, but there's something in the silk of your dress that is not normal fabric, nor is it anything normally used on fabric. I suspect the silk was chemically treated in some fashion, or woven with a tiny impurity. I have no idea why somepony would do either of those things. I'm aware of different kinds of chemically treated fabric, and as I said this isn't a normal treatment. You might need a chemist to tell you more about what this is."

"Oh Celestia no!" Twilight yelped, then quickly cast a spell on the dress. I didn't have to ask which spell it was, because it dawned on me at the same time. Finally, Twilight breathed a sigh of relief.

"What in Equestria was that about?" asked Sassy Saddles in a hushed tone.

I planted a hoof over my face. "Something we should have checked beforehand: the possibility the dress was a vector for a biological weapon. We really need to be more meticulous than this, Twilight. We can't assume any unknowns."

"Wait, is there some kind of contagion?" asked Sassy Saddles. She looked horrified, and I can't blame her—particularly in light of all of the repeated inhaling she just did.

Twilight shook her head. "We're completely safe. There's biological contamination on the dress, but there's nothing alive or growing on it. It's undoubtedly just run-of-the-mill microbes you find everywhere," she said. "I'm really sorry about the scare, Sassy. We've been a little paranoid ever since this thing started. For all we know, there's no real danger and we're all overreacting."

Relief washed over Sassy's face. "Oh, thank goodness," she said, then looked nervous once again. "What about a chemical toxin?"

I shook my head. "Highly improbable. We'd notice the effects by now, and it would be all over the dress, not just infused into the silk."

"Curiouser and curiouser," said Twilight, quoting a certain dead author with a creepy fetish for little fillies. I privately wondered if she'd chosen that quote because Sassy was from Trottingham. Her accent was almost invisible, but my sense of hearing was much better than my sense of smell.

"We really appreciate your time, Sassy," I said, trying to be nice. I reached up to shake her hoof, and she took my hoof in hers. She had a firm squeeze, and she looked very happy. Did I make her happy just by being nice to her? Twilight seemed right about her insecurity, but it felt good to get along with her, even if she was a needy sort of mare.

Twilight turned to Sassy. "I'd like to buy your copy of the dress," she said.

"Are you sure? You can borrow it if you like. I can't really put it in the rotation until I hear back from Rarity," she said. "Besides, you are a princess."

"I don't have the bits on me right now, but can you hoof the bill to my castle?" asked Twilight. "I'll include a generous tip for your time and the payment delay."

Sassy smiled from ear to ear. "Of course!" she said, in a voice that sounded half-rehearsed for sales. Then her expression changed. "But please be careful, both of you. I don't like the idea that you might be in danger! I'll check with my staff to see if we had a second copy of the dress that we sold, but I'm 99% certain we didn't, because I open all of the shipments personally."

"It's okay. Don't worry about following up unless you discover something new," said Twilight. "We'll limit our visits here until we know what's going on in order to avoid getting anypony else wrapped up in whatever mess we're in."

Sassy Saddles rolled her eyes. "Now that's overreacting. Princess, if anypony trying to mess with you shows their tail in this shop, I can promise you they'll be hogtied with packing tape and hoofed to the guard so fast they won't know what hit them," she said.

I giggled, despite myself. It was a pleasant mental image.

Sassy gave us two boxes to keep the dresses packaged in so we wouldn't have to float them around in the open like a couple of idiots. Then we said our goodbyes and left the shop. I made sure to take the club with me, but I was starting to regret bringing it. Even with all the weirdness we were facing, I was clearly being paranoid and Twilight was just nice enough not to say anything.

Twilight took an unexpected turn on our way back to her observatory, and I realized we weren't going back to her place after all.

"We're going to my lab, aren't we?" I said, already knowing the answer.

"I have to try something," said Twilight. "You don't have to come with if you don't want to..."

"Ha!" I barked. "Like I'm going to let you run an experiment without me." This was convenient for another reason, too. I decided I might as well leave my stick at the lab, where I could hide it behind my desk. Twilight's observatory already had all sorts of objects I could smack an intruder with. It was weird, but I was starting to feel like my own lab, under lock and key (and now, presumably under guard) was the least safe place for me to be. The reality of the danger we were facing was starting to break through into my conscious awareness. Who knew what experiments Starlight Glimmer had already performed there? What if the next time we opened a door it was a loaded cannon pointed at us? The worst part was I knew neither one of us could turn our backs on my research now. It was too important, and we were both too bucking curious for our own good.

We hastened our pace to a trot. "I can't wait to hear what you're planning," I said, declining to share my trepidation. "I wasn't inspired experiment-wise by our meeting with your friend."

"She's more of a business associate than a friend, but I should probably think of her as a friend," Twilight said. "Sassy's a sweet pony. I mean, not half as sweet as you, or anything."

I wanted to say something, but I just felt really weird inside. Was that some kind of a compliment? Was it a joke? I didn't think she was making fun of me. I didn't know what to say, so I didn't say anything. I'd decided to wait until we got to the lab to see what Twilight had planned.

True to Twilight's word, there were two guards stationed at the lab. That was something of a relief to see. I let Twilight unlock the door, then I followed her into the building and directly into the experiment area.

"Hoof me the store's dress," she asked me. "This is a crazy idea, but it just might work."

"I have no idea what you're doing, but here you go," I said, taking the dress out of the box and levitating it to her. She took it into her hoof and sniffed it to confirm it was the right one, then opened the door to room zero. There was no discharge this time, and the room was empty.

"First part of experiment two—or make that one, if we're counting from zero. The room appears empty," said Twilight.

"Thank goodness," I said. "I have no idea what we'd do with three dresses."

Twilight laughed. "You know, science probably shouldn't be this funny," she said. I just smiled, and turned on my horn to cast some light into the dark alcove.

"Here goes everything," she said, and she tossed the dress into the room by hoof.

It only took a moment for the dress to hit the floor. It didn't act the way that physics should have dictated, however. It fell normally, but after it landed on the floor the part nearest the doorway scrunched away from us. It looked like part of the dress was getting sucked into place by some unseen force.

Naturally, we were both surprised by this effect. We could hardly be blamed for being caught totally off guard three seconds later when all Tartarus broke loose.

Getting Off of the Right Hoof

The dress landed on the ground and inexplicably scrunched away from us. For the next three seconds, Twilight and I stood there and wordlessly stared at it.

My first thought: there was a small creature hiding in the hem of the dress. I quickly dismissed that idea as unlikely due to the tight curves of its shape. While I struggled to formulate a better hypothesis, the dress winked out of existence, right before our eyes.

As most educated ponies know, memory isn't by any sense a literal record of events. It's a hodgepodge mess of connections stored in the brain, and any sense of coherence comes from the process of reconstructing the memory from those connections. It's an imprecise and error-filled process, and most of us aren't consciously aware of it because our minds fight against that kind of awareness. For example, as ponies living in a logical society, we feel the need to give 'reasons' for our actions. But the reasons we claim don't actually predate our actions: studies prove we make them up after the fact. Memories are very similar in that respect.

What happened to me when the dress disappeared was so chaotic, I had to piece it together afterwards. It went something like this.

I was standing right next to the door, while Twilight stood behind me. The moment the dress disappeared, I felt the air being torn from my lungs and my body shot forward into the vacuum that now filled experiment room zero. The heavy door also slammed shut, or at least it tried to. My right forehoof was, for better or worse, in the way.

By all rights, this should have been a horrible disaster. The door was heavy enough to break my hoof in two, and then I would have been locked inside the room for ninety minutes as I bled, potentially to death, inside a chamber whose full function was yet to be determined. I might also have suffered pressure damage to my eyes and skin if the air pressure had failed to fully stabilize before the door slammed shut. My survival would have been likely, but it would not have been an enjoyable ninety minutes.

Thank Celestia, I lucked out. Instead of losing a hoof, I heard the crack of the door on my hoof (I went into shock so quickly I barely even felt it), but something else blocked the door well enough to prevent it from doing more damage. Apparently, the piñata stick had been sucked partway in, and the fat end of it stoppered the door. Twilight's hoof was braced against the stick on the outside, which helped in two ways: it kept the stick from entering the room, and it wedged the door open even wider. This saved my hoof from a severe break.

I started gasping for air as the pressure stabilized, and Twilight squeezed her legs into place in the door to help extract me. The next thing I knew, I was lying on the cold, metal floor outside the room.

"It's okay, Moondancer," said Twilight, although her eyes were wet. "I've got you." I lifted off the floor as she levitated me up. A few moments later we were outside and one of the guards had flown off to get a medic.

I was feeling pretty dizzy. "Thanks," I said to my friend. She laid me on the grass, but kept my hoof elevated with magic. I glanced up at it, and it looked pretty awful. Cracks ran up both sides, and there was some blood dripping from the medial.

"I'm so sorry," whispered Twilight. She was crying and trying not to look me in the eyes.

"Hay, it's not your fault," I said. I reached up with a forehoof to touch her cheek. "Your quick thinking saved my hoof, and maybe my life."

Twilight shook her head. "It was dumb luck," she admitted. "The suction pulled me toward the door too, and my hoof hit the stick at just the right time to leverage the door open."

"It'll be okay. I'll live," I said. I looked over at my cracked hoof. "Shit. I hope I didn't break the coffin bone."

Twilight shuddered and said nothing, but I knew exactly what she was thinking. I've seen the pictures in medical textbooks. Repair of a broken coffin bone is painful, time-consuming, and horrific to look at.

I gently petted Twilight's mane as she leaned down to hold my neck. Before I knew it, I was passing out in a hospital bed.

It was morning when I woke.

"You're lucky," said the doctor. Twilight was standing right beside her, her face a mask of worry.

"Tell me something I don't know," I joked. "I can still feel my hoof, after all. Not that I want to, mind you." I looked up at my hoof. It had been placed in a walking cast, which already told me everything I needed to know: there was no break, and I'd be out and trotting again within twenty-four hours. I winced from the pain.

Twilight reached over and pushed a button on a hoofheld device next to the bed, apparently intended for my use. I wondered what it was supposed to do, but seconds later I knew.

"Oh, that feels nice," I murmured as the fire fizzled through my IV, and I smiled up at Twilight. I'd been hospitalized previously, but meperidine had never felt like this before. It must have been a high dosage.

Twilight sighed. "I'm just glad you're okay. We really need to be more careful than this, Moondancer."

"Don't blame yourself, Twi. Neither of us could have foreseen this possibility," I said. "And now we know for sure. We just need to stopper the doors at the start of each experiment."

"Ms. Moondancer, the Princess informs me that you are already familiar with your condition," said the doctor. "But just to be clear, your hoof is going to be fine. You need to keep this cast on for a week if possible, so we'll schedule you back when you're ready to head out. No cantering or dancing or anything, just a light trot at most, and preferably keep it to a walk and stay off of it when possible. We don't see any cracks on the X-ray, but there may be a hairline fracture in your coffin bone. We need to keep you under observation for a few hours after your last dose of IV painkillers, and then you can go."

"I don't suppose I can keep the IV?" I said, trying to sound as sarcastic as possible. "I'd like to leave soon, but I'm probably going to dose again the next time it starts to hurt that badly, and Celestia knows how long that will keep me stuck here."

The doctor smiled. "Princess Twilight Sparkle has already picked up a prescription of oral painkillers and agreed to manage your care. You can take those instead, once the pain is light enough. I daresay you're in good hooves," she said.

"Well, I think I'm in great hooves," I countered, reaching out to squeeze Twilight's hoof with mine. Then I did something very silly, which surprised me—must have been the narcotics—because I winked at her, and Twilight blushed. The doctor blushed a lot deeper, though.

Me, winking at a princess! I loved it. I was such a ham.

"I'll... leave you two alone," said the doctor. She walked off quickly and shut the door behind her.

Twilight buried her muzzle in my barrel for a moment, then came up for air. "I was so worried, Moondancer."

"These things happen, Twilight. Even if the door had shut, I would have survived," I said.

"We don't know that."

"Eh, it's probable. I still don't know how that flimsy stick saved me, though. It didn't even break, did it?" I asked. "Piñata sticks are designed for foals. They shouldn't be that durable, even though it is surprisingly heavy for a toy."

Twilight grimaced. "Well... it's not really a piñata stick."

"Wait, what?" I said. "Where did you get it?"

Twilight smiled oddly. "They didn't have any piñata sticks at the store when we went to prepare for your party, and we were short on time. And I wanted your party to be perfect, naturally. So I chopped off and sanded down one end of a baseball bat."

My jaw dropped (figuratively, of course). "Seriously? Back when I brandished it at you at my party—I could have given you a concussion with that thing!"

"Heh, well, these things happen, right?" said Twilight, with a cute grin. "It's all water under the bridge."

"I guess," I relented. "Anyway, now that we know about the vacuum, we should be safe from here on out."

Twilight stood up and shook her head. "No. Moondancer, we need a reasonable theory before we can proceed with further experiments. This is simply too dangerous."

I groaned in objection, but Twilight was right, as usual. "Ugh. I haven't had time to think, but I'm not sure thinking would even help. What happened is categorically impossible. Teleportation?"

"The field can't possibly break; that's an absolute, just like you said. And if it could, there would be no more building after the inevitable explosion," said Twilight.

"Then all we're left with then is a violation of the conservation of energy, which breaks all of known physics. That isn't acceptable," I stated.

Twilight pursed her lips. "I've had time to think while you were sleeping, and I have an idea. But I need your quantum mechanical experience."

I nodded, instantly curious. "Well, let's hear it," I said.

"What if—not saying how, just what if—the test chamber could create a closed timelike curve?" said Twilight.

I stared at Twilight, then I stared at the wall. I tried to put the pieces together in my drug-addled head. She was patient, kindly enough.

"You mean what if the antimatter is actually travelling backwards through time?" I asked.

"Exactly! Maybe there really is only one dress. Then the one we put in might be the same one that came out," said Twilight.

I suddenly realized why she needed to do that experiment right away. "You had this idea from the very beginning," I said. "That's why you wanted to do the experiment right away. No wonder you sound so guilty. It makes perfect sense that the air would disappear, which was an oversight."

"I'm so sorry—"

"Stop, Twilight," I growled. "It's fine."

"But I should have told you what I was planning, and taken more time to think," she said. "That recklessness caused your injury."

"Maybe. I don't care. I might have done the same thing in your case," I said, and it was true. "Anyway, that wasn't the cause, because your theory is completely wrong."

"What?" said Twilight.

"It can't be a closed timelike curve, Twilight."

"But it has to be, it's the only..."

"That's faulty logic," I said, rather gruffly. I saw her face fall, and I felt a little bad, but sometimes you have to rip that bandage off fast.

"Okay, okay. So what's wrong with it?" she asked.

"Several things. First off, it isn't the same dress. It's a different type of silk, and it's been chemically treated. Remember?"

Twilight frowned. "Maybe the process of becoming antimatter and going backwards through time could have changed it at the molecular level?"

I shook my head. "It couldn't change the chemical composition—that doesn't make any sense," I said. "Besides, in order for something larger than a particle to be part of a true closed timelike curve, entropy would have to be reversed for the entire system."

"But that's possible!" said Twilight, her face brightening. "I thought about it, and it might explain the energy drain whenever you run an experiment. Some of the magic power is feeding the system to reverse entropy within the field."

I paused. "Okay, that might fit. Although I feel compelled to point out that the statics of the energy drain are highly inconsistent," I said. "The energy draw has been fluctuating wildly ever since I hooked the thing up, and it even varies between experiment rooms. The only room that never seemed to pull energy was room two..."

"That's the room that was sabotaged! Why didn't you mention this earlier?" asked Twilight.

"Because it was coincidental and irrelevant. That sort of physical damage to the door isn't something that could have been caused by a mana surge, or even a faulty seal," I explained. "I determined that even before I installed the camera that caught Starlight Glimmer in teleport."

"I guess that's fair. But we're left with only three possibilities. One, or I guess zero to be extra-dorky, all of physics is wrong. One, I'm right about the time loop, but for some reason it alters the chemical composition of matter inside the box. Or two, there's a possibility we haven't thought about yet," she said. "I believe my theory is still the most likely."

I shook my head. "It has to be the latter. For what happened to be a loop, there would need to be... Here, hoof me that notebook and a quill."

I took the quill with my magic and drew a line on the paper representing time going to the right, and another horizontal line separating the inside and outside of the chamber. On the separating line, I placed a circle for the first time the door was opened, followed by a square for the first time it was shut—and then a second time for the next time it was opened and shut. I drew a set of arrows showing the dress entering in the middle of the latter window of time in which the door was open. The arrows reversed direction just short of the door being closed, headed backwards through time, and reversed direction again right when the door initially opened. Then the dress exited in the middle of the first open-door period:

"Let me see if I follow," said Twilight. She pointed with a hoof at the left side. "The leftmost circle represents when we opened the door the first time, and the place the dress exits is where we picked it up. Then we shut the door at the leftmost square, waited, and the second circle is when we opened it again. We threw the dress in, and it disappeared moments before the door tried to close for the second time, due to the air also disappearing."

"Right. From the dress's point of view, we threw it into the chamber during the second experiment. Time reversed for it when it disappeared, then it saw the door 'shut' when we opened it. The dress sat in the room a while, going backwards through time," I continued. "Then time reversed a second time for the dress at the moment we initially opened the door for the first experiment, and that's the point where it came out. But there's a problem with this theory. Can you spot it?"

"Well, I'm going to guess it's that 'gap' you marked between the time the dress disappeared and the door tried to shut," said Twilight. "And even then, the door didn't actually shut all the way. As far as I know, it's a mystery what activated the second half of the experiment."

"While that's true, there's a larger problem. There are two dress worldlines in the same space, Twilight," I pointed out. "There should have been two dresses occupying the same position in space at the same time: once after we opened the door initially up until we removed the old dress, and once after we threw in the younger dress up until it disappeared. That isn't possible."

Twilight grinned. "But it is possible! If you're actually reversing time, the manner by which your field is separating the matter from the antimatter would allow two sets of spatial coordinates to occupy the same place," she said. The satisfied grin on her face was kind of adorable. I regretted having to wipe it off so soon.

"Okay, that's pretty bright. That might even explain the motion of the dress when we were removing it and adding it," I said. "It was being literally pulled out of, and then sucked into, the time loop. But you're missing something even more obvious. Look at the diagram, and think back to our experiments."

Twilight's brow furrowed. "I'm not seeing it. What is it?"

"Antimatter isn't invisible, Twilight," I said, flatly.

"I... No, I still don't get it. What do you mean?" she asked. I was kind of surprised she hadn't put the pieces together, to be honest. That sort of thing can happen when you're stuck in an otherwise-beautiful theory, though.

"Antimatter has equal but opposite electrical charge. So it absorbs and emits light in the same way that normal matter does," I explained. "The only difference is that the light that gets emitted has opposite polarity. Think about the antimatter version of the dress, before we shut the door the first time, and after we opened the door the second time."

Twilight sighed in frustration and planted her face in her hooves. "Oh, horse apples, you're right!" she said. I could forgive her the profanity, though. I'd have felt the same way.

"If your theory were correct, when we removed the dress from the experiment room we would have seen it split into two dresses: the normal matter dress which we removed, and the antimatter dress travelling backwards through time, which essentially would have been the past trace of the removed dress," I said. "Similarly, when we went to throw the dress in, it would have already been sitting there. Tossing it in would have caused it to scrunch into place on top of its dual, then both dresses would disappear when the time reversal activated."

Twilight sat and thought quietly for a few minutes, and I let her. I was still reeling from the drugs, and I needed a moment's rest after that much conversation.

"What if the antimatter were made invisible?" she finally asked.

"I'm listening," I said.

"It might be possible to invent a spell that could render antimatter invisible," she said. "If it actually is a closed timelike curve, then antimatter should maintain a unique signature within the field. Magic could also terminate the loop early, before the door is shut."

I shook my head. "Either spell would need to be cast from the basement, and there's no logical reason somepony would do something like that."

Twilight bit at her lip. "Starlight Glimmer might have done it, maybe to throw us off the track of realizing what your work is capable of," she said. I saw her shudder slightly, and I felt it too. The idea that Starlight Glimmer might have been in the basement of my lab while we were upstairs was not exactly comforting.

I snorted. "Ugh. We'll need to check the entire lab, then," I said. "But it's still ridiculous on the muzzle. If your theory is correct, then I've created a device capable of time travel of the first kind. There's already a spell that can do that, and that kind of time travel is highly limited in utility because you can't use it to change the past. The only benefits of my research would be that my lab allows it to be done to inanimate objects, and it could be performed multiple times by the same user."

"And it would be much easier to modify Star Swirl's spell to do that than to sabotage your lab," admitted Twilight. "If it is time travel of the first form, Starlight should have figured it out by now, and she wouldn't need to go to all this trouble to confuse us. I guess we're back to square one. We'll both need to hit the books and see else we can come up with."

I nodded in agreement.

Twilight sat with me and read to herself for about two hours until I was ready to be discharged. While waiting, I tried to nap, but my mind was tortured by all the possibilities. Some of the facts seemed to point to time travel, but there were too many impossibles in the way.

Everything together suggested Starlight Glimmer's involvement. It seemed obvious she was trying to 'fake' time travel with my experiments. But she must have known Twilight and I would figure it out, so for what possible reason?

Who in Equestria could benefit from a fake time loop?

The Six Minute Plan

Once I was up and mobile, we headed back to the lab.

Right out the hospital door, I picked up the pace to a gentle trot. It didn't hurt my leg much, but a moment later I felt a hoof pulling back on my chest. Twilight was holding me back. I turned to look at her, and she had a concerned look on her face.

"Why don't we walk?" she asked, faking a smile (badly). "It's such a nice day."

I sighed dramatically. "Fine," I said. "Your motives are transparent, Twi. It really doesn't hurt that much when I trot."

She smiled and reached an arm around my withers for a side-hug. "I just want you to relax a little, Moonie," she said gently. "We both want you out of that cast as soon as possible, so let's take it easy, okay?"

I furrowed my brow in response to the word "Moonie". This was the second time she'd said that, and I was certain I hadn't given her permission for a nickname. I wasn't her pet, for crying out loud. But then I realized I'd called her "Twi", so maybe that made my name fair game for continued pettification. It was irritating, but I deigned to shrug it off. I could tell I was bothered by it more than I should be, and I knew she meant well.

So I sighed again (less dramatically this time) and nodded. "Fair enough. I guess a little caution won't kill me," I joked, and then returned to a walk.

Twilight kept one hoof around me for the first few steps as we walked, which was awkward because she had to skip on the fourth beat. It felt nice, though. I was a little embarrassed to be seen like this, and I didn't quite know why. I realized I had a lot of anger inside me I still needed to work out—not at Twilight, ironically enough, but at everypony. I was kind of bitter about growing up without friends. Looking back, I could see that ponies tried to be nice to me over and over, but I just shut them all out. I decided that improving who I was as a pony would require a modicum of embarrassment and tolerance, and I'd just have to bite the bit and do it.

Twilight deserved that much from me, I figured, and it was a good thing I had someone like her to keep my eagerness in check. Oddly enough, I seemed to serve the same role for her. I thought it was weird how we could compliment each other's weaknesses, even when those weaknesses were exactly the same. Maybe, I thought, it was simply because we cared more about each other than about ourselves.

This last realization made me feel uncomfortable. I was certain I was beginning to read too much into Twilight's actions. She was being such a good friend, but I figured she probably just felt obligated to be nice to me. It didn't really matter, though. Her help meant the world to me, and I was very lucky to have it.

Twilight could tell I was lost in thought, so we walked in silence all the way to the lab. Once we arrived, she spoke with one of the two guards.

"Guardstallion, we need your assistance," said Twilight. "We need to do a thorough search of the interior of Moondancer's laboratory to make sure that somepony hasn't been hiding inside there the entire time. The pony in question may be a very skilled mage, so this might be somewhat dangerous."

"Of course, Princess. Should I go for more guards?" asked the stallion.

Twilight shook her head. "Between the three of us, we shouldn't have any difficulty handling her. I just want you to be prepared for a confrontation."

"Always, your Highness."

Twilight rolled her eyes. "Please, just call me Twilight," she insisted.

Twilight opened the door and the three of us entered the lab. The guard shut the door behind us. I walked to the entrance to the test chamber anteroom and motioned to the guard.

"I need you to stand here, and keep your eyes both on the test chamber anteroom and this entrance area. Twilight and I will go to the basement, then one of us will come up and walk through the bathroom," I explained. "That should cover the entire lab, and we'll be casting spells to sweep the area and guarantee there's nopony else in here with us."

The guard nodded and stepped into place. I opened the door to the stairwell, and Twilight and I headed into the basement.

"This is neat! I really should have come down here sooner," said Twilight. I supposed it was kind of neat down here. The ceiling was glowing, though not as brightly, which provided a spooky sort of mood-lighting. Four sections above were dark, and it was clear from the layout that those were the experiment rooms. Each of the four sections had a small box attached in its center.

"Not that it needs mention, but this," I said, pointing to the large box in the middle of the floor, "is the magilectric transducer. Those boxes above are the field generators, and obviously the cables between the transducer and the generators supply the power directly."

"Wow. I've never seen mana transduction cables this thick before!" said Twilight, touching one with a hoof. "This research involves a lot of firsts, Moondancer. It's really incredible what you've done here."

I nodded. "Once I ponied up the dough and explained the generalities of my research, Princess Celestia gave me full permission to begin construction. I have to admit, I was surprised it was so easy to win her over. I guess my track record as a student was sufficient for Celestia to place her faith in me."

Twilight opened her mouth as though to say something, then shut it a few seconds later. "Let's get the scanning underway," she finally said. "How should we proceed?"

"Hmm. Why don't you scan the basement from end to end, then I'll clear the stairwell and move to the top floor?" I asked. "It shouldn't take more than a minute. I'd prefer if you stayed down here until the scan completes, just to make sure nothing screwy happens where the power feeds in."

Twilight nodded, and began a scanning spell. Beams of magenta light cut across the basement in a sweeping motion. There was some shimmering and sparking when it swept across the transducer, naturally. Once her scan touched the stairwell door, I stepped into the stairwell and met her beam with mine.

Then, something marvelous happened. It only lasted for a second, but I'd never felt anything like it before. As her magic touched mine—her magenta scan brushing and merging with my soft pink—I felt a strange serenity filling my entire body. I knew that Twilight felt it too, because I saw her eyes widen for just a second. In that tiniest moment, I felt what she felt, and she felt what I felt, and it was like sharing the warmest, most personal hug one could imagine. She turned off her magic right after we both felt it, probably as an automatic reaction from surprise. I doubt it was because she didn't enjoy it; I'd have done the same in her position.

I opted to say nothing, and backed up the stairwell as I scanned. I wasn't certain what had just happened, but my heart was calm. Today I had already discovered that oxycodone was something like a warm, comforting hug that wouldn't let go (no wonder ponies get addicted to it, I thought). But it couldn't hold a candle to this feeling coursing through me. Even after the contact broke, I could still feel it inside, like a piece of Twilight had come along with me for the ride up the stairs. I hadn't read anything in the literature about merging two scans. Were we the first to discover this? I had to put it out of mind so I could focus on the task at hoof.

As I walked up top, I continued the scan. "Don't worry, this won't hurt," I said to the guard, and I ran the scan through the room until it covered the guard and entered the other room somewhat. Then I opened the bathroom door and started walking through it, pulling the scan area through it while maintaining the boundary where the guard stood. This was very tricky, since I could no longer see the boundary I was maintaining. For a moment I postulated that maybe I should have had Twilight do this part. But I liked a challenge, and I wanted to be competitive with her. Competitive with a princess? My ego could handle that.

Once I'd exited out the other side of the bathroom, I was easily able to pull the scan area together and sweep the scan across the anteroom. It flickered on the outside of the test area doors where magic was being negated. I dropped the scan and breathed a sigh of relief.

"Excellent, we're safe. Do you mind?" I asked the guard, who stepped out of the way so I could pass through. I shouted down the stairwell: "All clear!"

Twilight quickly came up the stairs. "Great! Thanks very much for your help, Sir," she said to the guard.

"Of course, Pr—I mean, um, Twilight. Is there anything else?" he asked us both.

"Yes. Don't tell anypony about what we did here or what you saw," I ordered. "Our research is secret, and keeping it private will help to ensure our safety."

"Yes, Miss Moondancer," he said, with a very serious face. It was all I could do to keep from laughing, it was so cute. The guard headed out of the building and closed the door.

Twilight and I stared at each other for a minute. Each of us was probably thinking about that magical mixing caused by the scanning spell, but neither of us wanted to say anything.

"Oh, let's um, look at the experiment rooms," she finally said, blushing fiercely. I realized then that I was blushing too. I followed her silently into the anteroom.

"I scanned as close as I could get to the doors," I said. "So if Starlight Glimmer is hiding here, she'd have to be about a millimeter large and smashed up against the metal."

"Wait! What about the experiment rooms themselves?" said Twilight.

I thought for a moment. "If your theory about time travel is at least partially correct, that would be impossible."

"Oh, that's right," said Twilight, planting a hoof against the base of her horn. "If she were in the experiment rooms going backwards through time, she'd have to be out here afterwards, and now that the place is locked down, that can't possibly happen," said Twilight. Then she frowned. "But my theory is false, so that's no real comfort."

I looked at the floor and saw a few dots of dried blood. The pinata stick was also here, with slight dents on either side of the fat end. I teleported in a rag from inside my desk and conjured some water, then proceeded to wipe off the blood.

"All theories are false," I pointed out while scrubbing the tiny drops of my blood off of the glowing metal floor. "Your theory on time loops explains some things, but can't explain others. We need to figure out exactly what these rooms can do," I said. "Installing some automatic stoppers would be a good first step, but as soon as we do, we'll need to run more experiments."

"Maybe we should keep guards inside this room, in case Starlight is in one of the experiment rooms?" suggested Twilight.

I paused in thought. "No. That's a bad idea. If any details of these experiments leak, we could end up attracting even more trouble," I said. "Whatever we have here could be dangerous in the wrong hooves, don't you think?"

Twilight nodded. "And it's not safe for us to watch in shifts, because Starlight Glimmer would have a reasonable chance to overpower either of us one-on-one. Our only hope is to figure this out quickly enough."

"The evidence just doesn't make any sense," I complained. "Our first experiment produced something out of thin air, which is strictly nondeterministic: it was an event that could not have been predicted by any means. Not only does that violate conservation of energy, it violates CPT symmetry and even the most basic tenets of determinism."

Twilight shook her head. "Everything must be predictable, even if it might not be predictable for us. There must be a probability distribution that defined the state of the room prior to the first run," she said. "Cause and effect are still things that happen."

"But even if the experiment looked like a perfect closed timelike curve, we'd still have an ontological paradox. Who decided to use the dress?" I said. "The dress basically decided it would be used, before it was used. The causal predecessor is its own downstream effect."

"Ontological paradoxes aren't a problem. I've been part of one," said Twilight. "The book even mentioned them, remember?"

"It's still weird," I grumbled. "Anyway, the timelike curve theory would be viable if the antimatter version of the dress were present during the tests, but it wasn't," I said. "In retrospect, I think that's the bigger problem of the two. The fact that the two dresses weren't identical is mind-boggling, but the changes to the dress are more of an unexplained mystery than an outright impossibility."

"I can't explain the changes to the dress," said Twilight. "But the absence of the antimatter path... it's a form of symmetry-breaking, Moondancer. Maybe we should look at it as an example of time travel of the first form where something goes wrong?"

"Let's pretend for a moment you're right. How in Tartarus do we devise an experiment to test it?" I said. "We just open a door at random and hope for the best?"

Twilight looked a little hurt. "W-well, I..."

I winced. "Ugh. I'm sorry, Twilight," I said, and walked over to hug her. "I'm just frustrated, and I'm not as practiced at holding my temper as you are. I'll try to calm down."

"It's fine," said Twilight, with a wry smile. "And actually, I think I may have an idea. But we need to put metal stoppers in front of the experiment rooms first."

Twilight stayed in the anteroom while I left to rent some welding equipment and purchase metal contraptions. I didn't like leaving her there alone, since for all we knew, Starlight Glimmer could pop out of one of the rooms at any moment. But she was more capable than I would have been. We would have sent a guard to do our shopping instead, but describing what we needed would have been too difficult.

Both Twilight and I were relatively certain the remaining rooms were devoid of unicorns, but I made haste just to be safe. I remembered after cantering off that I was supposed to keep to a trot, and the pain made me slow my pacing. Fortunately I'd brought pain medication with me in my saddlebags. I made it back in a jiff, and only slowed to a walk after I entered the lab.

"Moonie?" said Twilight. "You're back already?" She wandered into the main area with a look of concern on her face. "I can't believe I forgot about your hoof! Tell me you didn't run..."

"I kept it to a brisk trot," I said. "We both know your safety is more important than a stupid unicorn hoof." I levitated a bunch of equipment and slowly walked into the anteroom. I tried to hide it, but Twilight noticed my limp.

"Don't do this again," she ordered me, with a stern frown.

"You're a princess, Princess," I said, my voice tinged with bitterness, even though I wasn't certain what had gotten into me. "You're more important."

Twilight looked uncomfortable. "I... Well, yes, you're right," she said meekly. "But I don't want you hurt if it isn't necessary."

I didn't expect that. I didn't really know how to feel. But it was true, wasn't it? Twilight wasn't just important because she had wings and a horn, I realized. She was important because the fate of Equestria frequently rested upon her saddle.

"Let's just get to work," I said, trying unsuccessfully to put the thought to the back of my brain.

I illustrated how I thought the stoppers should work. Essentially, we were placing a circular row of metal spring-up teeth into a slider, then welding the slider in place in front of a door. I brought three, one for each of the remaining doors. The teeth would normally be in front of the door, so pulling the door open would ratchet it past the teeth and lock it into place. To shut the door, the slider would be unlocked, and then the teeth could be slid out of the way of the door. Simple and elegant.

Twilight and I both donned welding masks and got to work. We couldn't hear well over the din of welding through the muffled masks, so the next fifteen minutes left each of us alone in our thoughts. That was not a place I wanted to be. I kept thinking about how important Twilight was, and how unimportant I was, and how this would never be a healthy friendship for us.

At some point, Twilight had used magic to air-quench the welds. I hadn't noticed. I was deep in a bad place.

We took off our masks. I wiped my brow. We were both pretty sweaty. I could feel the sweat trickling down my cheeks, even. Then I noticed Twilight was staring at me oddly.

"What?" I said, very softly.

Twilight gingerly reached over and wiped at my cheeks. Her eyes were tearing up a bit. It was then I realized that I had been crying. I'm not sure when it started, but it certainly hadn't staunched.

"Oh. I didn't know I was, um," I said, and then she leaned into me. We sat on the floor and I cried into her neck. I didn't know what was going on. She stroked my back gently, and I clung to her as tightly as I could. After a few minutes I pulled away.

Twilight sniffed and wiped a tear from her own eye. "Moondancer, I... I don't want to be more important than you."

I nodded. "I know," I said quietly.

We sat there for a moment in silence, nopony knowing what to say. I figured that everything had already been said.

"You wanna get cleaned up?" I asked. "The bathroom has two sinks." Without waiting for a response, I stood up and walked to the door. I didn't limp this time; physical pain was nothing compared to the feelings striking me in the gut, and I wasn't about to start another round of baby-eyed bawling.

After I'd washed and dried my face and shoulders, I turned to look at Twilight. She was looking in the mirror. She looked wrecked. I probably looked the same way, but I wasn't willing to look at myself in the mirror. Heck, even when I'd had myself together, I didn't like looking at myself. I never thought there was anything worthwhile to see.

"Twi, it's okay. I dunno what's wrong with my feelings, but it isn't your fault. I'm glad you're who you are. I love—I mean, I like that about you," I said, then felt warmth in my cheeks. I hoped with all my heart that what I'd just blurted out didn't sound as stupid to her as it did to me.

Twilight smiled warmly, and then just as quickly it vanished. "It's not just you. Princess Celestia puts all this pressure on me, and I just... I'm not willing to be who she is," she said. I wasn't really sure what she meant by that.

"Well, maybe you should just be yourself, and to Tartarus with her," I said. I immediately regretted it (I hated being so terrible at social conversation), but to my surprise, it made Twilight laugh.

"Yeah, sometimes I'd like that. I get away with being myself whenever I can," she admitted. "And actually, so does Celestia, in her own way. She has a quirky sense of humor. Hay, can I tell you something in secret?"

I shrugged. "We've been sharing secrets for, what, days now? Go right ahead."

Twilight took a deep breath. "I've been working on a spell that Princess Celestia knows about, and it's rather macabre."

My ears perked up. "Don't leave me in suspense," I said, and cracked my first genuine smile of the day (not counting the drug-induced kind).

"It's a spell that will allow the caster to relive the last few days of another pony's experiences," she said.

"Holy Moon above! That's amazing!" I said. Suddenly, my recent funk seemed a distant memory. "Could I use it on you someday? Could you use it on me? Just imagine what you could do with it! But... wait, why is that macabre?"

"Well, there's a catch," grimaced Twilight. "It only works shortly after the pony has, um, kicked."

"Kicked? I don't—"

"The bucket," said Twilight. "It works on the very recently deceased."

I felt a chill tickle at the back of my neck. "Oh gosh, that's kind of sick," I said. Twilight immediately looked distraught. "No, wait! Oh, Twilight, no. I'm so stupid, ignore me, everything I say is wrong..."

"Moondancer, you're fine. And you're not stupid or wrong, either," said Twilight. "Look, it's obviously going to be a useful spell, and I'm pretty close to completing it. But it's not something I would have thought of on my own. Celestia put the pieces together and determined the spell was possible, and then she told me about the idea and suggested I work on it."

I closed my eyes. "I get it. You think she's trying to toughen you up," I said. "This Princess is really starting to piss me off."

"She means well, Moondancer. I need to grow," said Twilight. "It really is for my own good."

"Twilight," I said, walking forward and holding her by the shoulders, "in a lot of ways, you're still just a kid. You might be twenty-four or whatever—"

"Twenty-five."

"—again, or whatever, but you were pretty much friendless too until a couple of years ago. You need more time and space than Celestia is giving you," I said.

"I know. I've needed to tell her for a while," said Twilight.

"I'll tell her for you," I resolved.

"No, Moonie, please..."

"No, I will. Look, I'm no Princess of Friendship," I said, again immediately regretting my choice of words. "But I've already learned it's not a bad thing to accept help from your friends. I'm not going to embarrass you, I just want to talk to her sometime, and if it comes up it comes up."

"Maybe that would help," said Twilight. "I just don't want to think about it right now. With this vague danger lurking out there, and what already happened to your hoof, I'm scared of losing you, Moondancer."

"I'm going to be fine," I said, and then I hugged Twilight and I kissed her cheek.

I had no idea why I kissed her cheek.

It was really, really weird. It was so weird I froze, but Twilight just nuzzled my neck in response and said, "Thanks." Then she smiled at me.

"I, um, er, I... um," I said. "Um."

Suddenly, Twilight's eyes shot wide and her mouth dropped. "Ohmygosh! I have an amazing idea for an experiment we can do," she said. She paused for a moment, then took my hoof and led me back into the main area of the lab.

I was too nervous to say anything after being a complete weirdo, so I just gave her my full attention, which was a lot of attention.

"Okay. This is going to be a little strange, but here goes. I'm going to go into the basement," she said. "I need you to do exactly what I say, okay?"

"I, sure. Wait, what?" I said.

"I can't explain it fully, or it might not work," said Twilight. "I swear, it's essential. But I'll tell you in six minutes."

I groaned. I already had the general idea of what she was planning. The basement is the only place a pony could cast spells into the test chambers. I had absolutely no idea which spell she was going to try, and not knowing was positively maddening.

"If you were any other pony, Twilight. But I guess I'll play along. What do I do?"

"I'll go to the basement. Wait precisely one minute, then go into the anteroom and open experiment room zero. No, wait! Make that experiment room one," she said. "I assume we're still keeping to the plan of checking each experiment room."

"Twi, you're not going to do something dangerous and stupid, are you?" I said, scrunching up my muzzle in worry. She had a glimmer in her eye that looked suspiciously like somepony who was planning to do something dangerous and stupid. As curious as I was, I didn't want to see Twilight Sparkle hurt. One injury in two days was more than enough, thank you.

"Trust me," she said, notably not answering the question.

I shrugged. "What happens after I open the door?"

Twilight paused in thought for a moment, like she hadn't considered this most basic part of her plan. This made me feel even less confident. "Oh! Okay, so here's what you should do. After you open the door, keep it propped open. Then wait five minutes. Then come to the basement and get me."

Twilight was smiling like that pink friend of hers, which is to say she was grinning in a way that was both endearing and frightening in its intensity.

"You promise this is not dangerous?" I said, putting on my best you'd-damn-well-better-not-be-endangering-yourself face.

Twilight nodded. "Yes. The logic checks out perfectly," she said, her eyes scanning rapidly back in forth in front of her. "Wait one minute, open room one, wait five minutes, then come get me—but make sure you come get me right after five minutes because that's the most important part. Then you can tell me what you saw, and based on the results I should be able to explain what happened." She was practically bouncing in place with excitement. As nervous as I felt, her mood was catchy.

"Okay, let's do it. This time without losing a hoof, I hope," I said, rolling my eyes.

"You'll be fine," said Twilight, as though reassuring herself more than me. "Yes. You'll be fine. There are numerous possibilities but none of them should be dangerous for you. Remember! One minute, room one, five minutes." She ran downstairs before I could say anything else.

I grabbed a stopwatch from the desk, then walked into the anteroom and began pacing as it counted down.

"Horsefeathers. I don't like this, Twi," I murmured to myself. I had a strong sense that Twilight had just decided I was now more important than she was, after all that drama. I wasn't about to let something happen to her, but I was so insatiably curious, and she seemed so eager and confident...

It was the longest minute I'd ever had to wait through, but it finally ended. "Time's up," I said, just to convince myself I was ready.

Of course, I wasn't ready. But I didn't have a chance to hesitate, because I had to keep to the schedule. In my mind, I cursed Twilight for rushing me into this, but I swiftly opened the door to experiment room one. There was a static discharge, and a windy rush of warm air blowing out of the room. I lit my horn to look inside.

Waiting five minutes was no longer an option.

One Little Plastic Bag

I opened the door to experiment room one, and out walked Twilight Sparkle. But "walked" wasn't the right word. She stumbled, and she stumbled very oddly.

Initially she just stood there, staring at me. Her mane was a little mussed up and parted oddly, and she wobbled a little. Then she seemed to strain her muscles against the empty air. It looked a bit like she was walking through a blob of clear gelatin.

That's when the stumbling began, but maybe that wasn't the right word for it either. She lifted and set down her legs in a strange manner. It wasn't until much later that I realized where I'd seen that motion before: it was almost like she was walking backwards, except that she was moving forwards.

I would have reached out a hoof to help her, but I was stunned. My brain had already put two and two together and I didn't want to admit it. I could accept the fact that she'd been right about my experiment allowing for time travel of the first form, but I couldn't believe that she'd gone and done something incredibly dangerous right after reassuring me that she wouldn't.

After a few seconds of awkward straining, her body lurched forward and she landed on the floor in front of the door. All of a sudden, I could hear her breathing—deep and labored.

I reached down to offer her a hoof up. Once she stood up, she grinned at me, and I promptly slapped her across the muzzle with an open hoof. It wasn't hard enough to cut or break anything, but it definitely packed enough of a wallop to sting. I had never been able to hide my emotions well, and at that moment I was positively shaking with anger.

Twilight looked hurt: first physically, then emotionally. "W-why...?" she gasped.

"How DARE you!" I whisper-shouted. "Here you are warning me to be careful and you decide to do an experiment in the antimatter chamber with yourself?! You could have been killed! Or maybe even killed me in the process! We have no idea how this thing works, Twilight!" I made a mental note of the fact that it is difficult to speak clearly with a deep scowl yanking at the corners of your mouth.

Twilight winced and began to cry. "I, I know," she said, "but hear me out: if it hadn't worked, then you would have come to tell me..."

"I don't care about the logic! I don't even know what to think right now," I growled. "Even if you knew it would work, you didn't stop to consider what this would do to me."

"But... I thought you would be happy!" said Twilight, grimacing. "I'm so sorry, I—I just..." she said, wiping her eyes. Her hoof was moving erratically, like she had a hard time controlling it. She must have been really upset, I thought. I started to feel a little guilty myself, so I actively worked to suppress my rage.

I sighed and held my hoof over my face. "Look, Twi. I know the siren call of science as well as you do. But you just can't do shit like this without consulting me first. Think a little bit next time, okay?" I asked, then reached out to place a hoof gently on her shoulder. "How would you have reacted if I'd tried to use the experiment room right after what happened with my hoof?"

Twilight nodded, sniffling. "I know, I know. You're right, and I'm sorry," she repeated, then her eyes widened. "Oh no. We have to get out of here right now. I can't believe I have to walk out of here looking like this in front of the guards. Not that I don't deserve it, but I don't want them thinking you did something to upset me..."

"What are you talking about? I have to go talk to the other Twilight in... horse apples! I forgot to hit the stopwatch. About three minutes," I said.

"No! You can't talk to her," said Twilight Sparkle, grabbing me by my shoulders.

I narrowed my gaze. "You told me I was supposed to go talk to you after five minutes, no matter what."

Twilight nodded. "That's the whole point. If you had gone to talk to me, I would have known the experiment didn't work. Then I wouldn't have entered the room in the first place. That was my failsafe."

I was starting to get the idea. "I think I follow. But then, you wouldn't have really known it was a failure, would you? This could have been a useless test. You were allowing whether or not you entered the room to become another ontological para—" I said, then stopped short when I realized the implications. "Wait a second. You're going to come upstairs in three minutes and enter the room, aren't you?"

Twilight shook her head. "I didn't want to chance something weird happening by entering the room with the door open for the entire duration of the experiment, even though that might actually work. So I stayed downstairs for ninety minutes and read a book. But four and a half minutes after I went downstairs, I turned off the sound bubble so that I'd be able to hear you."

I shut the door to the antimatter chamber, realizing the necessity to complete the time loop. "Okay. That gives us a little over a minute..." I glanced at Twilight, and she really did look terrible. In addition to puffy eyes, she teetered back and forth as though she were about to fall over.

"We have to leave right now," she said, with a sigh. "It's okay. I'll just hold my hoof over my eyes as we exit, but—"

"Did you go to the bathroom? We could hide in there and put up another sound bubble," I offered.

Twilight shook her head. "For ninety minutes? I'm already three hours ahead of you, Moonie. I've been sitting in the experiment room all by myself for another ninety minutes—same ninety, different direction—because I didn't remember to bring the book with me into the chamber. Now I'm exhausted, I'm feeling nauseous, and I'm having trouble telling direction... I don't think I can handle staying in this chilly building for another hour and a half. I need you to lead me outside. Please," she begged me. "There's not much time. I didn't heard the door slam while I was downstairs, so we must have exited sooner."

I frowned. "Dammit, Twilight," I said, then carefully led her by the hoof to the entrance. I steadied her gait with my magic, and we were outside within a minute.

As planned, Twilight held her hoof over her eyes when we exited. With her head bowed and her legs shaky, it was very obvious she wasn't feeling well.

"Princess, are you alright?" asked one of the guards. I walked Twilight to some grass beside the building and helped her lie down.

"She'll be fine," I said. "The princess had something that didn't agree with her stomach, and she needs to rest."

The guards didn't seem placated by that, so Twilight said, "Moondancer is correct. I'll be okay, I just need some rest." She kept her head turned away from the guards as she lay down on the ground. It was warm out, fortunately. I was still very angry with her, but I felt bad for her too, so I lay down beside her and held her gently.

In truth, I was lying more "on her" than "next to her". I was glad she seemed partly okay, but I was still filled with worry. What if the trip through time had scrambled her brains? What if this illness were more than just motion sickness?

I cuddled up closer with my foolhardy friend, no longer caring that we were being watched by a couple of stallions. It just didn't matter anymore. Twilight was what mattered, and I wanted her to feel better. I tucked my muzzle up against her chin, and I could hear her heartbeat through her carotid. I wasn't sure why, but holding her felt amazing inside. I could feel a strange warmth filling my core and kissing my pelt, and it wasn't just the sun and her body heat. Maybe this was what true friendship does to you, I wondered. I hoped so, if only because that might mean that Twilight really was my friend. For some reason I'd never fully accepted that idea, and I suspected it was because she was so much more important than I. Why would she spend time with me, of all ponies, I wondered? It was a simple equation that didn't add up.

"I won't ever do this again," she murmured, and I felt the tension ease in her spine.

"Good," I said, and I gave her barrel a little squeeze.

We stayed like that for a few minutes, until one of the guards cleared his throat. Twice. Three times...

"What is it?" I said, lifting my head, and then I saw it too. "Um, Twilight?"

"Hmm?" she said, a silly smile on her face.

"Your butt is flashing."

"Huh?" she said, then craned her neck backwards. "Oh, nuts. The Map is calling me."

"I'm going to guess this is one of those things that can't wait," I said.

Twilight stood up uneasily, then shifted her weight from foot to foot. "I'm afraid so. I think I can manage, but I could use a lift. Guard, could you get a taxi for me?" One of the guards immediately took off.

"This is that Cutie Map artifact you were telling me about, isn't it?" I asked.

"Yes. It means somewhere in Equestria, somepony needs my help with a friendship problem. Probably one or more of my friends need to come, too. I'll know when I get to the throne room," she said. "Once I visit the Map, my cutie mark will stop flashing. It flashes again briefly when the problem is solved, but the problem could be anywhere in Equestria, so this might take a few days."

"Weird. Well, you should let me come with you," I said. "You still seem uneasy." I wanted to add 'your mane looks off' but I figured she'd fix it herself when she could finally balance on four legs.

Twilight shook her head. "I'd love to have you come with, but the Map is highly particular about who should go on a mission. If you were supposed to come, your mark would be glowing too."

I sighed. "How can I possibly counter that kind of logic?" I complained.

She smiled wanly. "Well... When the Map doesn't invite somepony, it usually means that if that pony were to come along, she'd accidentally solve the problem in a way that wouldn't fix the underlying issue," Twilight explained. "I know it sounds stupid, but it holds up historically."

"Right, extension of the Tree of Harmony and all that. Could I at least come with you to the castle?" I asked.

"I'm tempted to say yes, but I don't want to take you away from our work here. Er, I mean your work," Twilight said, correcting herself.

"You were right the first time. It's our work," I said with a genuine smile. "And yeah, I need to do some research as soon as possible to figure out why you're dizzy. That shouldn't happen. Also, you still smell a little like ozone? Which is weird."

Twilight nodded. "Yeah, I noticed that. Maybe it's in my pelt or something. Look, I'll be back as soon as I can. If you need to contact me, you can send a royal scroll my way. Although I probably won't receive it if you wait too long, since Spike doesn't usually come on our trips and he's still rigged as my personal receiver."

The taxi arrived, and I helped Twilight into the carriage.

"Wait!" I said, quickly grabbing the door of the cart so the driver wouldn't take off yet. "What am I supposed to do when you come out of the building?"

For a moment Twilight froze in thought, and then she laughed. "I already did! Just don't go into the lab for the next eighty minutes," she said. "Think it over, you'll get it."

I waved as the taxi took off toward the train station. Then I felt a hoof on my shoulder.

"Forgive my forwardness, Ms. Moondancer. But you do know the Princess really likes you, yes?" one of the guards whispered in my ear.

I blushed and turned my head. "Yeah, maybe she does. I guess we're pretty good friends," I concluded.

"Of course," said the guard, with a mischievous-looking grin.

The other guard chuckled. I didn't get it.

I spent the next few hours doing research at Twilight's place before I was interrupted by a knock on the door.

I answered the door, and to my surprise, I saw Princess Luna looming over me. She's scarcely half as tall as her sister, but she still stands nearly as many hooves high as a Clyde. I stood aside so she could enter.

"Greetings, Moondancer. I was hoping to find you here," said Princess Luna. Her magical mantle rippled through her mane and tail, glowing like a night full of twinkling stars and nebulae. It was hard for me not to stand transfixed by its beauty.

"Yeah, sorry Twilight is out at the mo—wait, did you say you were hoping to find me?" I asked.

Luna smiled and chuckled. I was a little surprised by her pleasant demeanor. Twilight had told me once she was 'hard to get to know', but right from the start she struck me as personable. Maybe with a strange, stilted way of speaking, but what can you expect from somepony who missed the past ten centuries?

"Indeed," said Luna. "As a point of introduction, I find 'Moondancer' to be a most endearing name," she said, with a smirk.

"Thanks," I said, blushing. I'm not sure why I was blushing, though. It was obviously a joke at my expense.

"As it were, that brings me to the intentions of my visit. I would like to meet the mysterious foalhood friend of Twilight Sparkle," said Luna.

I rolled my eyes. "Ah, I see. You want me to dish some dirt on her."

"Hmm? I fear that I do not ken the expression, but I want nothing foul from you, Moondancer," said Luna. She looked a little hurt, and I felt guilty even though it clearly wasn't my fault. "I desire to meet you. My sister tells me you are engaged in research with Twilight Sparkle, and Twilight has also bragged about your prowess as a scientist."

"She... she has?" I said, legitimately shocked. Was Luna exaggerating, or did Twilight actually speak well of me to other princesses? I wasn't certain which possibility frightened me more. "Well, I'm flattered. Yeah, we both like science a lot. I guess that's why we're working together."

"And you are friends, as well," added Luna, with a nod.

"Oh, yes. I'm kind of new to the 'friendship' thing, I must admit. Even though Twilight and I knew each other when we were young, we weren't very good friends to one another," I admitted. "We had so much in common, too. I wish we'd spent more time together back then, but I guess we're making up for lost time now."

"That is most wonderful to hear," said Princess Luna, with a bright smile. She walked over by the couch and sat on the floor. I took this as a cue to sit on the couch so we could talk eye to eye, so I did.

"I don't really have much else to offer," I said. "I'm working on a project right now, but I don't feel comfortable revealing details unless Twilight were here to agree to them. She recently joined my research team. Er, I guess two ponies counts as a team?"

"I would be very interested in learning more, at another time," said Luna. "I have been reviewing your recent publications."

"Oh, really?" I said, unable to hide the surprise from my voice. "Quantum mechanics wasn't well-understood back when, um, you were around." Saying that felt incredibly awkward.

"Indeed! It is a most fascinating subject, and I have found myself searching and re-searching through texts for truth. I am as intrigued by the concepts as I am vexed that they yet elude my ability to make sense of them," said Luna.

I chuckled. "That's normal," I said. "Quantum physics isn't something that makes sense in the same way that other sciences do. Feincolt understood it conceptually better than anypony, and even he said, 'it's safe to say nopony understands quantum physics', or something like that."

"So how, then, did he manage to grasp its truths?" asked Luna.

I grinned. "There's a secret, actually! It's a hard one to learn, but it's simple: don't try to explain quantum phenomena with classical analogies. They won't work."

"Ah. Like the odd fact how you cannot measure a particle's velocity and position at the same time?"

"Actually, that's one of the false analogies. It isn't about measuring; and it's momentum, not velocity. The fact is, particles don't possess both a position and a momentum at the same time," I explained. "It's not that we can't measure them, it's that those two values genuinely do not exist together! I could go into more detail, but it would take time to—"

Just then, Twilight Sparkle threw open the door. She was holding the stopwatch from the lab, and she had her saddlebags on.

"Moonie! I need you. Oh, um, hi Princess Luna. This is kind of an emergency at the moment," said Twilight Sparkle. I blushed at being called 'Moonie' in front of another princess. Nice work Twilight, you goofy egghead, I thought.

Luna stood up and smiled gently down at me, then turned to Twilight. "Pay me no heed, Twilight Sparkle. I shall return when your friend Moondancer is free of obligation, so that I might endeavor to know her better still," said Luna, who then yawned. "It is the middle of my sleep cycle, so I must return to my repose. Carry on with your science!" She speed-trotted out the door and shut it with her magic.

"Wow. Luna was here to see you? It must have been important for her to get up in the middle of the day—" said Twilight, and that's when I noticed something was wrong.

"Wait a minute. Your butt is still flashing?" I asked, scraping the floor with one hoof. "You couldn't possibly have traveled to Ponyville and back in four hours. Shouldn't you be on the train right now?"

Twilight blushed, then shook her head to recover. "There's no time to explain. I'm in great danger."

"Twilight, what is going on?" I demanded, my muzzle all scrunched up. I was peeved, and it was showing. I could tell she was hiding something from me, and I had a good bet on what.

She winced. "I am on the train to Ponyville right now."

"You used the antimatter chamber again?! I can't believe it!" I said, covering my face with a hoof. "Oh Twilight Sparkle, for crying out loud! Didn't we just go over this?"

"I didn't have a choice!" she said, then crouched down in a begging position. "Moondancer, please, you have to help me or I'm going to die," she said.

I walked over and picked her up. "You crazy mare. Of course I'll help you. Just tell me what to do," I said. "You can explain this mess later."

"I'll try to brief you as we walk to the lab," said Twilight, and with that we took off.

I was far more worried than mad. I could sense time travel shenanigans were painting Twilight into a corner, and I had no choice but to play along. My hoof cast gave us an excuse to keep the pace to a trot.

"Here's the short version," said Twilight. "After I arrive in Ponyville, Applejack meets me at the train station and my cutie mark stops flashing when she tells me the two of us are bound for Dodge Junction," she said. "That should happen very soon. Unfortunately, the fact that I don't actually disembark at Ponyville allows me to miss an extremely important detail—you'll figure that out on the way, though. When I arrive at Dodge Junction, I drink a sarsparilla and become violently ill. The doctors were going to hydrate me with an IV that probably would have killed me, but you arrive in time to save me. Without running, by the way, so don't even think about it."

"The doctors there must be idiots," I said. "Or was somepony trying to murder you?"

"Neither," said Twilight. "I don't need to explain, because I'm sure you'll figure things out long before you arrive at Dodge Junction. I'll just focus on the important details so you'll have time to make the train. It leaves very soon: it's roughly five hours behind the previous train, and it also passes through Ponyville. I should probably have grabbed you sooner, but I was famished after my second trip through the chamber so I just ate a big meal. Besides, this is the earliest you'll be able to grab the item I need you to bring with you."

I was insatiably curious, of course. "I'd better figure things out on the way there, or you'll never hear the end of it," I teased her.

"You will, trust me. But some things still have to be secret for now. I've arranged it so we're sharing the burden this time: some things are hidden from you, and others from me," she explained.

"Argh! Twilight, why?" I asked. "Look, I want to help you, and I'll do anything you tell me to if your life is on the line, but if I had some idea why you keep hiding details of these experiments..."

"To avoid breaking symmetry," said Twilight. "After these recent experiments, I no longer believe that antimatter shifting is time travel of the first form. I'm all but certain that symmetry breaking is possible. If we do break symmetry, that could add all kinds of noise into the equation. Unknowns of that magnitude are highly dangerous."

"Antimatter shifting? I approve of the name," I said. Then it finally clicked. "Oh! You're keeping me in the dark so I don't accidentally do something differently from what you experienced," I realized. "That way we don't have to worry about symmetry breaking introducing any unknown quantities into what happened. Thank Celestia, this is finally making sense."

"Right," said Twilight, with a soft smile.

"Actually—after you went back inside, how did you get out of the chamber without having somepony there to open the door for you?"

"I brought a... um, a heavy vibrating tool with me," said Twilight, with a blush. I wasn't sure why she was blushing. "It vibrates enough to shake open the door latch from the inside, as long as the door isn't locked down completely."

"Must be one hay of a vibrating device to overcome the audio dampening effect of the field," I said, then looked up and noticed we'd arrived at the lab. "Instructions," I barked.

"Okay, listen carefully. Go inside the lab. I'm currently in experiment room one, going backwards through time again. I need you to open experiment room zero, which will unlock in about... four and a half minutes. The room should contain a paper bag. Remove the bag, then make certain you shut the door to room zero. There should be a half-liter dee-ten-en-ess intravenous bag inside the paper bag. Take out the IV, place the empty paper bag into the bathroom, and close the bathroom doors. Then come out, and we can talk for a moment before you head to the train station," said Twilight. "Did you get all that?"

I paused for a moment. "Yes," I said. "I take it you can't come to Dodge Junction with me, though."

"I need to go get the IV from the hospital and place it in the room when the door finally unlocks again. You'll understand when you examine the IV on your train ride," she said. "Also, I can't see the paper bag, because that could complicate things, which is why I need you to do the retrieval. Anyway, do that, then come out and I'll tell you the rest."

I was eager to help Twilight, but even more eager to find out what else she would tell me. I silently wondered if that made me a bad pony as I unlocked the door and headed into the lab, taking Twilight's stopwatch with me.

I stewed in thought as I waited, but my brain wasn't going anywhere productive. After the stopwatch showed five minutes had passed, I opened experiment room zero. A familiar blast of wind and ozone lauded another visitor from the future. True to Twilight's word, the occupant was one brown paper bag. I pulled it out of the gelatinous-feeling air, moved the ratcheted teeth aside, shut the door, and withdrew the plastic IV bag. There was nothing else in the paper bag. I tossed the bag on the bathroom floor, shut the bathroom door, and exited the lab.

"Everything went as planned, and the doors to room zero and the bathroom are both shut," I announced to Twilight. Her bottom was still flashing and it was hard not to stare directly at it. It was almost mesmerizing, and it wasn't just the flashing, but the shape of it somehow drew my attention, too. I didn't understand, but I forced myself to look up at her face. "Now what?"

"Here's a ticket for Dodge Junction," Twilight said, and hoofed me a ticket with magic. I picked it up with my aura (holding multiple items with delicate care was trivial for a practiced mage like myself).

"And when I get there?"

"Find the clinic. Tell them if they give me any dextrose IV other than this one, it might kill me," she said. "If they don't believe you, hoof them this scroll."

"Oh. Your butt just stopped flashing," I pointed out.

"I must have arrived in Ponyville, then. I wonder how long it's been off for?" she asked.

"Literally just now. I was watching it this whole time," I said.

Twilight blushed so hard the inside of her ears pinked.

I cleared my throat, then nabbed the scroll out of the air as well. For a moment, I landed the ticket in my hoof and looked at it. "Okay. The train leaves in just over thirty minutes, so I'd better trot to make sure I'm not late. Now Twi, can we please agree not to do anything else with the experiment rooms until we regroup? I'm getting a little tired of saving your magic flashing ass," I joked. I winked at her to emphasize that it was a joke, but it felt awkward.

Twilight blushed and smiled. "I promise, Moonie," she said, and she leaned out and kissed me on the cheek.

I felt really, really weird about that. Is that something friends do, I wondered? I couldn't imagine that colts did that sort of thing to each other, but maybe fillies were different. The weirdest thing was how nice it felt. It felt like a reward for helping her, and that didn't make any sense, because I wasn't a colt. We were both fillies. This was an obvious fact.

I smiled like a goof, then trotted off.

"And don't run!" Twilight called out. "When I woke up, AJ told me you didn't have to run to get there in time!"

I ignored her warning and broke into a light canter as soon as I crested the hill. It hurt a little bit, but I wasn't going to leave anything to chance. The cantering was made easier because psychologically I felt a little like I needed to run away from that awkward exchange. I had this bizarre electric feeling all over my flesh, and it just wasn't normal. It felt almost like having a special somepony, I thought, although I didn't really know what that felt like. Twilight was obviously very special, but again, we were both fillies, so it made no sense whatsoever. I tried not to think about it, and my mind had mostly cleared by the time I arrived at the train station.

I'd made it with ten minutes to spare. I got on the outbound to Dodge Junction (via Ponyville), sat down, and lifted my cast onto the train seat—given the circumstances, I doubted anypony would mind. My hoof throbbed painfully, but I didn't regret my decision.

I set the scroll in my lap. It was sealed, but that was kind of the point. I already knew what the contents were, anyway. I gently lifted the IV bag up with one hoof and examined it for the first time. It was 10% dextrose in normal saline, just as Twilight had said. It had all the typical boilerplate warnings, which I carefully read. It was marked Canterlot General, and had a separate copyright notice from the plastics company. Nothing really seemed out of place. But something about the bag struck me as a very odd design choice. Then it hit me like an anvil from the sky.

My short whoop of laughter startled the other passengers. Twilight was right, as usual. This little plastic bag explained everything.

Breaking Point

I had a lot of time to think on the train. This was a good thing, because I had a lot to think about. Obviously, figuring out what Twilight meant by "you'll understand when you examine the IV bag" was priority zero. At least that part didn't take long.

I was feeling pretty proud of myself, as indicated by my aforementioned whoop of laughter. The required insight had been tricky, but that wasn't the true source of my felicity. I was happy because Twilight had had faith that I would get the answer, even though most ponies probably wouldn't have been able to. Twilight Sparkle was easily the smartest pony I knew (and a princess, no less), yet she didn't look down on me intellectually. I felt tickled deep within my barrel. A small part of me worried that my emotionality was foalish, but I tried to rationalize it as yet another benefit of true friendship. I felt so fortunate Twilight had returned to Canterlot to make amends with me. As far as I was concerned, she'd earned her silly title.

The tip-off to the mystery had been that I needed to read the text of the IV bag through the clear liquid, because it was printed backwards on the outside of the bag. It was easy enough to read because the liquid was transparent, but it made no sense that this could be intentional. No sensible pony would design essential medical equipment to be any harder to read than absolutely necessary. I briefly supposed it was possible the design could ensure that only clear liquids be used with the bag, but that would make for a confusing failsafe. Clearly this was some sort of machining mistake. Right?

Not so fast. The text should have been printed on the outside of the bag. If so, that meant the writing had intentionally been printed backwards! That couldn't be the result of a simple manufacturing error. Could it be a combination of an odd design choice and a production error, I speculated? Reverse-printing would be legible if it were printed on the inside of the bag (then a pony could read it without the liquid getting in the way), and a machine might have sealed the bag inside-out by mistake. But that didn't make sense, either: if the ink were intended to lie on the interior of the plastic bag, it could compromise the purity of the bag's contents.

The facts were inconsistent. Backwards writing couldn't have happened accidentally during the machining process. It couldn't have been backwards by design. The bag looked genuine, and nopony with any horse sense in them would make a novelty fake IV bag with a minor design flaw. I didn't have the most well-grounded sense of humor, but I was fairly certain something like this was too obscure to be a source of amusement (even to medical staff).

That left only one possibility: the bag had been altered by magic. And then it hit me: the entire physical structure of the bag must have flipped when it travelled backwards through time! That's why Twilight had to antimatter shift the bag to save her past self: it's because she had been shifted as well, and she apparently needed an IV bag that had also been physically reversed.

At first pass, this appeared to explain everything. Twilight's physical body must have switched parity following the first antimatter shift. The organs in her body would have been on the wrong sides, and the stripe in her mane would have been reflected (which would explain why her mane seemed odd to me). This is why it was unfortunate she didn't spend time in Ponyville: from her perspective, since her brain was backwards, everything around her would look backwards. When reversed Twilight walks and moves to the left, to her it must look and feel like she's walking and moving to the right. She would immediately notice her castle was on the wrong side of town, not to mention everything else in the city. That mirror effect was probably a big part of why she was disoriented after her trip through the antimatter shift: the lab, though mostly symmetrical, was backwards.

Twilight must not have paid attention to familiar Canterlot landmarks while she rode the taxi. Given how tired she seemed to be, I can't say as I blame her. Reversed-Twilight had already been awake for three hours longer than I had, and I know she's an early riser. The Sun was setting as I got on the train, so by Reversed Twilight's circadian clock, she was only a few hours from bedtime back when I had helped her exit the laboratory.

The mirror-symmetry also explained her illness. The transposition would have gone further than the merely physical and psychological. Twilight's body would have been reflected all the way down to the molecular level.

Chemically speaking, organic materials are made from molecules connected by covalent bonds. That makes them different from other materials, like metals or minerals. Specifically, biochemicals can have a very complex structure. They can be very large and complicated, which allows for the neigh-unfathomable complexity inherent to life.

There is a kind of physical symmetry that appears in any nonzero number of dimensions sometimes called "reflection" or "mirror symmetry". Three-dimensional biomolecules can be symmetrical (e.g. water), or asymmetrical (most large molecules, like proteins). The property of having reflection asymmetry is called chirality. Most biomolecules are chiral, which means their mirror-image has a different shape: the molecule can't be rotated and superimposed precisely onto its mirror image without leaving gaps. Chemists would say that most biochemicals have "left-hoof" and "right-hoof" versions (although which is which is an arbitrary label).

Since biomolecules tend to work together in a lock-and-key manner, the left-hoof and right-hoof versions of chiral molecules sometimes have different functions. For example, glucose is a simple sugar naturally produced by most life forms. The "right-hoof" version (called dextrose) is common, but the "left-hoof" version (called L-glucose) isn't natural. L-glucose tastes a lot like dextrose, but the pony body can't utilize it for energy, so it's basically an artificial sweetener. The only reason we don't use it as a sweetener is that it's hard to make in a lab: you can't get bacteria or plants to do the heavy lifting, because lifeforms won't synthesize it.

There are countless chiral chemicals like L-glucose that aren't produced in nature, most of which have unknown effects on the pony body. Twilight becoming ill after imbibing a soft drink isn't all that surprising. Her molecules were reversed, and even her DNA would have been rotated the wrong way around. Any interaction with biochemicals in a state like that could prove toxic, not only to her but to the organisms around her, too. The fact that she might need an IV bag with a sugar her body could digest (the L-glucose variant, which would be just like dextrose for her) makes sense, particularly if she were hungry and unable to digest nutrition from natural sources.

This theory also explained the odd behavior of the dress. It appeared to pull through itself as I tugged on it because it was switching parity as I yanked at it, and the odor was different because many scents are based on chiral molecules. The rare chiralities that aren't produced by life often can't be detected by olfaction because they don't fit into the same receptors. There's no evolutionary push for special receptors to exist for them because they're so rare. Even when receptors do exist, the smell can be very different.

And that's where the theory stopped making sense.

Saline and dextrose wouldn't have hurt Twilight, but she said the doctors were going to administer an IV that "probably would have killed me". That would make perfect sense for a blood transfusion, or perhaps for the administration of the wrong drug. The most common drugs she'd be likely to receive after falling ill from drinking something (setrons or antihistamines for nausea or inflammation) are probably safe, but they might have given her something strange. However, Twilight didn't mention that the IV she gave me contained any unlisted drugs. There was a place they could be injected into the bag, but she wouldn't have omitted data that relevant.

I supposed that Twilight might have mistakenly believed L-glucose was deadly, but I was doubtful. I realized the IV wouldn't likely be enough to save her. I would probably need to convince the doctors not to give her a drug they think she needs. That would be a harder sell than simply delivering a substitute IV bag, even though I had a scroll with her signature to back me up. This wasn't something I could afford to take chances on, even if there was already a safe-and-sound Twilight Sparkle already waiting for me in Canterlot. I still wasn't certain what form of time-travel we were dealing with, and I wasn't about to let any Twilight die. Not on my watch.

I was so deep in nervous thought, I didn't notice the train conductor until he cleared his throat multiple times.

"Miss? You do know you paid for a sleeping car," he said. "Bed thirteen."

Surprised by the interruption, I looked out the window. Tiny reflections of moonlight danced across nearby rock formations as the train traveled through the scrubland. Hours had passed me by.

"Thanks," I replied. I hadn't known about the bed, actually. It made some sense Twilight would have splurged on me. Maybe it wasn't such a splurge for a princess, but I wouldn't know—and either way, I wasn't complaining.

I took my things and headed to my bed. I didn't hear anyone else in the sleeper car with me, so for all I knew, I was the only occupant. I had slept in a train before, but never in a sleeper car. It was comfortable, but I knew I wasn't going to get much sleep. I was bothered by the real mystery.

The parity switch made no sense, because parity should have been conserved. It might make sense for an object to temporarily switch to its mirror image during the shift (although I couldn't think of a possible mechanism for that either), but why would parity still be reversed after the shift had finished?

It was still a clear violation of combined CPT-symmetry, and everything I knew about physics said that was impossible. The field I had created shouldn't have been capable of doing anything other than temporary matter alteration. The formula couldn't have caused a parity shift of any sort. And the problem of the antimatter disappearing was still there. The rooms weren't acting like a closed experiment. It was almost like the field was opening a portal between two very different worlds, similar in nature but acting like time-shifted broken reflections of one another.

All this unexpected data would have been exciting if it weren't so dangerous. I should have been energized by the prospect of discovering something new, but I was scared. This wasn't worth risking Twilight's life over. Nothing was.

Then I had a horrible realization, and my blood went cold. Twilight Sparkle wasn't the only organism to pass through the antimatter shift.

Her entire biome went with her.

Trillions of organisms had been reflected. Most of these were symbiotic gut bacteria, but there were also the bacteria living on her pelt. Ponies are surrounded by clouds of personal microbes from skin, gut, and oral cavity. They form a sort of unique hoofprint. All of the microbes that travelled with Twilight would have backwards DNA and RNA. What would happen if they found a way to replicate? What if they survived and became infectious? Our immune systems might not be able to combat them. They could wipe out civilization entirely!

I resisted the urge to hyperventilate, for two reasons. I hadn't had time to analyze the situation fully, and Twilight Sparkle had had the time. This would have crossed her mind too. Slowly, I reassured myself that parity-reversed microorganisms would not be able to take a foothold in Equestria. All life functions using fundamental building blocks, and most of the essentials are missing in a mirrored world. Since all but one of the amino acids that make up DNA, RNA, and other proteins are chiral, and many of those are not found in nature, mirror-image microorganisms would not be able to replicate long before falling apart.

I was fairly certain I was correct, but the idea was still unsettling. Even single-celled life isn't fully understood. It's too tiny, it's too complex, and it operates too rapidly. As scientists, we must rely heavily upon inference to understand cellular biology. Life spreads like wildfire into new territories, and some bacteria have inherent magical abilities (e.g. archeus magicum which live in a commensalistic relationship with the lesser tatzlwurm). Even in the best case scenario, Twilight had polluted Equestria with a completely new form of life, one unlike anything the world had ever seen.

There was nothing to be done but hope for the best. The odds were on our side, at least. When Twilight cast her biosignature spell on the dress, it detected no organisms. Based on how that spell would have to work, it should have detected living reflected organisms as well, and there would have been some still thriving on the surface of the dress if it were possible for them to replicate.

At some point I finally nodded off. My sleep was plagued by nightmares I wouldn't remember upon waking.

I awoke to bright sunlight, and slowly gathered my senses. I remembered my mission. I opened the blind and looked out the window of the train to a sunny desert day. Then I noticed the position of the sun, and the fact the train was still moving.

"HELP!" I shouted at the top of my lungs. I'd already gathered my things by the time the conductor arrived.

"Miss? What's the problem?" he asked.

"We passed Dodge City!" I said.

He nodded. "Ah, missed your stop? We'll come back on the return trip..."

"NO!" I said, grabbing him by the shoulders. "I'm on a life-or-death mission and Princess Twilight Sparkle is in grave danger!" I held up the scroll, which featured her seal embossed in wax.

The conductor grabbed the side-rope and yanked it twice, paused once, and then a third time. The train immediately ground to a stop.

"You're lucky. We're only a few minutes past the city. We can't travel backwards safely because another train is due soon, but you should be able to get back to Dodge quickly if you gallop," he said, then looked down at my leg cast. "Oh dear."

I shook my head. "It's fine, I can gallop. Thanks." I made sure I had the IV bag and scroll floating next to me and I jumped out the nearest exit.

The train started moving again, and I looked at Celestia's Sun above me. It was very hot. As much as I loved my old, ragged sweater, I needed to ditch it. I dropped it a few feet from the tracks in the thin hope I'd be able to recover it later.

I could see Dodge City several kilometers in the distance, and I started cantering toward it. The ground where the tracks lay was very solid. I considered detouring through the sands, but realized that I'd have a hard time making progress that way. Running on the hard earth hurt my hoof, but I had no choice.

As I cantered painfully along, I began to realize my gait might not be fast enough. I was still groggy from sleep, and my mind struggled to put the facts together. Twilight said that Applejack told her I hadn't needed to run to get there in time, and based on what I knew of Applejack, she wasn't the type to lie about that sort of thing. However, we already knew this wasn't time travel of the first form. There was no telling what might happen this time around. Symmetry had already been broken, so Twilight remembering that I'd arrived in the nick of time might prove to be incorrect. I didn't know what to expect. I simply had no basis for an accurate prediction.

I increased my pace to a full gallop.

Almost immediately, I learned that this was a questionable idea. A full gallop was very painful. Each repeated thump of my right forehoof increased the risk I would snap my coffin bone like a crescent-shaped twig on the next. My mind raced along with my body in a frantic attempt to buy me time. I held the scroll and the IV bag in front of me with magic as I ran, and I started cogitating possible magic solutions to get me there in a single piece. Teleportation wouldn't get me far enough fast enough, and I was too rusty with it (not to mention mildly nauseous from the recent painkillers). I could levitate myself if I needed to, but not for very long or very fast. I was an impressive mage, but no Starlight Glimmer.

I tried to create an artificial support with magic force. I needed mechanical advantage, and creating intangible training wheels on the sides of my cast would allow me to run without the repeated stress of hoof-fall impacts. I focused on a point in front of me to see if it a sturdy, moving conjuration were possible. It wasn't working. The axial connection wouldn't spin loosely without intense concentration, and I didn't have that ability with the pain throbbing in my right hoof. I settled for trying to protect my hoof with a soft magic cushion around the walking cast.

The moment I wrapped the cushion into place (mid-gallop), my next step sent me tumbling painfully to the ground. Fortunately I was able to keep the bag and scroll hovering above me as I slid on my barrel. The magic cushion had made my hoofprint thicker, which in turn had broken my gait. I cursed my stupidity for not stopping first to test it.

Magic wasn't going to help. I picked myself up, stretched momentarily, and focused my mental acuity on a virtue known to every mage: pure willpower. I broke into another strong gallop, faster than before, and fought with every fiber of my soul to disconnect the sensation of pain from the psychological experience. I began to partly dissociate my mind from my body.

I used the pounding ache to keep time. The shorter the interval, the faster I was running, so I played a little mind game to keep myself going. I timed each pulse of pain and tied it to my heartbeat, and managed to map precisely three heartbeats onto every two painful clops. I was using the pain against itself, and it was working. I'd never known I could run this fast at all, let alone manage it while in terrible pain. It was fascinating, and that fascination helped deepen the mental disconnect I needed to maintain my speed.

I was able to keep that rate consistent most of the way to the city, for several minutes (which felt like hours). It was amazingly hot out, even with no clothing on. My head was down, my nostrils flared. I was sweating, and I'd have been frothing if I were wearing clothing or saddlebags. Spittle gathered at the corners of my mouth. My vision tunnelled forward. For a subjective eternity there was nothing but my heart, the pain, the heat, and the sounds of grunting and clopping.

My next beat landed with a crack.

I flew forwards, quickly realizing I didn't have a contingency plan for flying end-over-end in excruciating pain. Without thinking, I instinctively launched the IV bag up high and fast into the air at as close to a normal trajectory with the ground as I could manage while being this disoriented and distracted. The scroll clattered to the ground behind me as the IV flew skyward, and I rolled forward like a tumbleweed with my poor, cast-covered hoof cradled into my belly. I had slid the telekinetic cushion back over it for extra protection, and this turned out to be wise. During the spill, my cast bumped against my barrel once, and even with the cushion it was enough to send stars shooting through my vision. Eventually I slid to a stop, scraping my left flank something fierce on a patch of gravel.

The first thing that went through my mind was a fascination that pain could actually be this terrible. I feared I would vomit or pass out, primarily because I needed to save my friend, but also because I might die of exposure in the desert myself. I immediately regretted how selfish that second fear felt.

Then I remembered the bag. It had only been a few seconds since I launched it, but my eyes scanned the sky in a state of panic. It was nowhere to be seen. My body shook with fear. Then, I saw a falling dot in the sky, far from the tracks. Too far for me to reach it with magic.

"Buck me," I whispered, then carefully fixated my eyes on a spot located roughly below the falling bag. There was nothing else to do. I had to teleport, so I realized I might as well get over with it now. It was hard to steel my nerves for the trip, but I wanted as much time as possible to recover from my ordeal before I had to catch the thing, so I focused almost instantly on the task.

Teleportation is a very hard spell. It's potentially dangerous in the hooves of a novice, and I was rusty. I was also in the belly of the worst pain I'd ever experienced. I knew I only had to shut the pain out for a fraction of a second to succeed. I thought of Twilight, dying in a hospital bed. I pushed every ounce of energy I had into making the jump. Right as I cast the spell, I realized I needed to project myself further from the tracks than the bag was falling because it had travelled in an arc. With that last calculation, I felt my body wrenching in two.

The pain was, somehow, even worse. Then I was lying on the sands and I craned my neck upwards. I needed to vomit, but I didn't have time. I saw something in the sky, but it wasn't the bag; it was an eagle. Then I saw the bag. The eagle was swooping in to catch it with its razor-sharp talons.

"NO!" I cried out horsely. Somehow, with the last of my reserves, I managed to fasten a magic bubble around the bag just before the eagle collided with it. The range was extreme, but I'd done it. The eagle looked irately down at me, but seemed less interested in the bag now and flew away.

I didn't have the energy to levitate the bag, but I kept it in the bubble until it smashed into a loose pile of sand. I helped cushion the fall by yanking the bubble slightly toward me right before it hit, which caused the bag to spin around inside the bubble, converting its downward momentum into angular momentum. I flipped onto my back as I rolled the bubble up to my chest, then popped it and caught the bag with my good hoof. I rested the bag on my chest, and examined it. There were no scratches of any kind.

I breathed a tremendous sigh of relief, then turned my head to the side and vomited into the sand and into my mane, somehow steadying the bag with my good hoof to keep it from falling off of my belly. I coughed and spit a few times, and it felt like I needed to emesis a second time, but after a minute of rest it seemed clear that wouldn't happen.

I levitated the bag slowly, and then staggered to three hooves. I thought I might be crying, but I couldn't tell. I snorted weakly. I started cantering forwards, minus one hoof. It was much more difficult to move through the sand. I used magic as my fourth hoof, and I used magic to keep the broken hoof safely aloft, but maintaining three spells was too exhausting. I reached the top of a dune before collapsing again.

I rested the bag on my back. The IV was hot; almost too hot for a safe infusion. I had to get to town faster than this. I could see the city from where I lay, and I could see one or two ponies walking through it, like ants in the distance. There was no way they could see me lying flat on the sand.

I closed my eyes tight and resolved not to give up, and then the obvious occurred to me. They can't see me, but they might be able hear me. If only my voice hadn't escaped my throat! Then I remembered my magic. I took a ragged breath, focused what mana I could still scrape together into my vocal chords, and shouted:

"HELP"

This was much louder than I'd expected. I heard hollering and saw a dust cloud forming. Within half a minute there were two strong earth stallions standing beside me.

"I must get this bag to Twilight Sparkle, matter of life-or-death," I wheezed. One of them carefully picked up the bag and placed it in his saddlebags, and the other helped me onto his back. They began to walk back to town.

"Don't walk. Gallop," I said.

My body was bruised and scraped, I smelled like fresh vomit, and I didn't have the energy to protect my hoof from the painful bouncing. The walking cast showed wear but no damage to it, so at least I didn't look grisly. I felt a relieving numbness in the tip of my hoof, and was fairly certain I was pooling blood within the cast.

This was yet another new experience: I could feel myself breaking. I shivered as though I was cold, even though I was burning up in the hot sun. I thought I might pass out. Somehow, I maintained consciousness. At the time, I thought it was my last remaining shreds of dignity. I later realized it was just my instinct to save Twilight's life.

"What do we need to do?" said the pony upon which I was rider.

"Princess Twilight Sparkle has fallen ill, but she may die if she receives the wrong medication. She needs that IV bag immediately because it has special medicine in it. I have a scroll with her signature that confirms my... shit!" I said, wincing. That was right. I dropped the stupid scroll.

"Whoa," said the smaller pony. Both ponies stopped and I nearly fell off my ride. The sand here had finally given way to firm ground. The smaller pony took the bag from his saddlebags and placed it into Packer's. "I'll go look for the scroll. Packer will take you to the infirmary."

"It's by the tracks," I said, and he took off. "Packer, there's no time to waste."

"Then y'all best hold on real tight, missy," said my ride. I put my undamaged left leg around his neck, and my rear legs tight around his barrel.

"Ready," I said.

It turned out that Packer could run significantly faster than I could, which tempered my pride a bit. It was all I could do to stay in place. I tried to use magic to steady my hoof, but only weakly succeeded. Packer's gallop was still agitating it painfully. I almost wanted to tell him to slow down, but I wasn't about to give up now.

Finally, we arrived at the infirmary. It looked modern and almost out of place among the wooden buildings. I felt like death.

"We're here to help, miss," said a doctor who immediately pulled out a stretcher as Packer walked me into the building.

"Have you seen Applejack or Twilight Sparkle?" I said. "Twilight has a temporary mudam, am, a, a medical condition that, she'll die if you give her any dr, drugs..." I stammered.

The doctor lowered me into the stretcher. "The Princess is under our care after fainting, yes," she said. "Is that what the IV is for?"

"Yes. She can only have the IV, and no other drugs," I explained.

"We have IV treatments here. She'll be fine."

"NO! This is a special IV! Dammit, you need to listen to me!" I shouted, and started bucking reflexively at the air.

"Hold your horses," came a voice I'd heard once before. "I do believe I heard my name. Moondancer?" Applejack trotted into view.

"Oh thank Celestia. AJ, please, you have to get them to listen," I begged. I started crying, except there weren't any tears. I was dehydrated, and probably in more dire need of an IV than Twilight.

One of the nurses took my temperature with an ear thermometer, and her eyes went wide. "She has a high fever and there's blood in her cast, doctor. This pony needs immediate medical attention."

Applejack glared at the doctor. "Hold up, now, this seems important. What's goin' on, Moondancer? Do you know somethin' about Twilight's sickness?"

"Yes. It would take too long to explain, but she's in great danger. The doctors need to give her the IV I brought from Canterlot, and no other IV or medication. No drugs, no shots, definitely no transfusions; only this IV, period," I said, wheezing a little as the last words came out.

"We were about to give her a standard IV, but I'm her attending and we haven't started yet. You arrived just in the nick of time. What's special about this IV?" asked the doctor.

"It says dextrose but it's L-glucose. Her body needs L-glucose," I said.

"That's... difficult to believe," said the doctor. "Ponies can't—"

"I understand the biomechanics, but I need you to trust me. Twilight sent me with a scroll to prove what I'm saying is true, but I dropped it in the desert as I ran here..."

Applejack removed her hat and looked me square in the eyes. "How did Twilight know this would happen?" she asked.

I sighed, and winced. "It involves... time travel."

The doctor stifled a laugh, but Applejack kept a straight face. She looked deep into my eyes, and it felt like she was staring right into my soul. Her eyes twitched left and right with all the intensity of a doctor performing surgery.

"Doc, you do whatever this pony says," said Applejack, and she replaced her hat.

"You, you have to be joking," said the doctor, coughing. "We're not going to treat a princess on the words of a hallucinating pony who wandered in from the desert!"

"If Moondancer says Twilight sent her, she's tellin' the truth. That IV she brought look good to you, don't it?"

"Well, it looks sterile, but it's very warm, and I don't see..."

"Give her it, and don't give her any other drugs until we find that scroll."

"Listen, Ms. Applejack. I'm bound by oath to do my very best for my patients—"

Applejack snorted. "Doc, I happen to know Twilight has dealt with actual time travel on at least two occasions. I don't claim to understand it a whit, but Princess Twilight Sparkle has been tellin' me that Moondancer here's one of the sharpest tools in the shed," she said. "I believe she'd trust this little filly with her life, and so then do I. Give her the IV."

The doctor looked skeptical, but the lines in her face softened as Applejack spoke. "Alright," she said, and took the IV into the fold of her wing. "But all three of us will bear responsibility for this decision."

I sighed in relief and slumped back against the stretcher. Two nurses carried me into a room and Applejack followed.

"I need to make sure that stubborn mare actually follows through, then I'll be right back to check on you," she said.

"Take your time," I mumbled, and I finally passed out.

A Broken Heart

An irritating, buzzing sensation slithered beneath my skin. My previously-insensate mind was no longer blissfully disconnected from reality. I opened my eyes. It felt vaguely like I was dreaming about being tortured. Applejack and the doctor who had attended to me earlier were standing above me. I lay on a gurney in a radiology room.

"Ms. Moondancer, do you know where you are?" said the doctor, in a dreamy, drifty voice.

It took me a moment to put things together. Everything looked fuzzy because my glasses weren't on. (I later realized it had been a miracle that my glasses managed to stay on my face through that tumble I took.) They must have been removed by the medical staff once I passed out.

"Dodge City Infirmary," I finally said. There was an IV in my left foreleg with a goodly amount of painkillers coursing through it. My right hoof hurt terribly, but it felt like the pain was just outside of my reach.

The doctor nodded. "Normally I wouldn't wake a patient like this prior to surgery, but Applejack insisted. She needs to talk to you. Is that alright?"

I nodded my head slowly. "Oh, doctor?" I said, though the words came out slurred.

"Yes?"

"You can safely give Twilight any drug that comes in a rate, a rayk, hold up—"

"A racemic mixture?"

"Yes. Yes, that. But the buffer too. Has to be. A mixture," I said.

"I suspected as much. We discovered shortly after starting the IV that her anatomical isometry was backwards, and based on the bizarre results from her blood samples, it appears the reversal is also molecular," said the doctor, with a brief smile. "She should be safe now. But we'll need to reverse her condition very soon, so if you know of a spell to do the trick you can tell us after surgery."

I nodded again, even though I knew that Twilight wouldn't need one. It was easier than speaking.

"Thank you kindly, doc," said Applejack. "Now if'n I can beg your pardon again, I do believe I need some time alone with Moondancer here."

"Ten minutes," said the doctor, wearing a stern frown. As she exited the room she grumbled something about the Elements.

Applejack shut the door to the lab and pulled out the scroll. The seal had been broken. "They found this. Your sweater, too, even though it was further out. I guess it was easy to spot from a distance."

I nodded.

"You were right as rain about Twi, but it's a good thing I'm the only mare to have taken a gander at this here scroll. Can you help me make sense of this?" asked Applejack. She opened the scroll and held it in front of my face.

Milk

Eggs

Sour Cream

Hay

Brown Sugar

I stared at the scroll for a while. "It's what Twilight gave me to... oh, bucking Tartarus," I said. Applejack's cheeks turned red and she coughed nervously.

"Lemme take a stab: more time-travel hoodoo? Am I warm?" she asked.

"Yes," I said, starting to feeling a little less groggy. "In the previous time loop, I must have told Twilight to write a shopping list down, then lie to me that it was a letter from her."

"But why? And for that matter, why would she go along with it?" Applejack asked. "Help a farmin' mare out. Use small words if you gotta."

I smiled. "You're not dumb, Applejack. This really is confusing, even for dorks like me and Twilight," I said. "I have no idea how the time loops started, but somewhere down the chain this happened, maybe by accident. I would have told Twilight to do the same thing she did in the last iteration in order to preserve as much symmetry between loops as possible. That increases the odds that Twilight will survive in the next loop."

"So for some reason she did somethin' weird before, which means she should do it again?"

"Exactly. But she can't use the same scroll. I'll need to write down a list of instructions for her to follow."

Applejack hoofed me a piece of paper and mouthed me a fountain pen. I picked up the pen with my magic, but it was unsteady and I couldn't use my hooves.

"Er, hold up," she said, and took them back. "You can just tell me what to write."

"Okay. Here goes..."

Dear Twilight,

This is Moondancer. Your molecular chirality has been reversed. You must follow these instructions to the letter to preserve as much symmetry between loops as possible. Immediately head back to Canterlot, time-travel back one day, and then come get me at your old place. Give me a scroll with your seal on it that lists "Milk", "Eggs", "Sour Cream", "Hay", and "Brown Sugar" in that order, but tell me it's a letter to explain your situation when I arrive at Dodge City to save your flashing butt. You might need some extra shenanigans if you think you'll be too hungry to last a day in the box. The rest you can figure out.

(Later, thinking back I realized Applejack probably misspelled words like chirality, since most ponies don't know what that is. But that was okay. Twilight was a smart cookie, and AJ herself was smart enough to realize it wouldn't matter.)

"That all?" asked Applejack.

"That's it," I said. "She can't be allowed to see that scroll, though, so trash it. Only give her the letter. Oh, wait—I do need you to do something else."

"Name it."

"You have to tell Twilight Sparkle that I didn't need to run to get here on time," I said.

Applejack furrowed her brow. "That ain't true, Moondancer, and you know it. Besides, she'll want to see you after surgery."

"You can't tell her I'm here, either. I know it isn't true, but it's important. If she hadn't told me that, I might not have realized I needed to do the opposite—"

Applejack groaned. "Now listen here, missy. I ain't no good at fibbin'."

I paused. "Well, just say the words, then. That's probably enough," I said.

"Look, sugarcube," said Applejack, as she placed a hoof gently on my shoulder. "I don't care for these time-travel antics. I may not understand the details, but I can tell when somepony's paintin' themselves into a corner with lies and deception, and that's exactly what this thing is doin' to you both. I'll do what you ask, but you gotta promise me this will be the last time you need to do somethin' so foalish. Find another way to go about it next time, alrighty?"

I closed my eyes and exhaled slowly. "No need to worry," I said. "Twilight and I will probably be putting a moratorium on our experiments after this mess, and neither of us will be using ourselves as guinea pigs anymore."

I opened my eyes. Applejack looked very relieved, then she paused for a moment in thought. "Her fault, weren't it?" she whispered to me.

I nodded. "Mostly, yeah. Don't tell her I said that."

Applejack smiled made the motions of a Pinkie Pie Swear, which Twilight had fortunately taught me on a previous visit to Canterlot. I nodded and smiled back. Applejack turned and opened the door, and the doctor entered.

"Are we done?" asked the doctor.

"Yes ma'am," said Applejack.

"Then it's time to scrub in and fix that damaged hoof," she said. The doctor uncapped a syringe and squeezed it into my IV.

As I succumbed to unconsciousness, Applejack leaned over and whispered something in my ear that my brain wasn't quite able to process.

"I really hope you know just how much Twiiiliiiiight loooooooveeeeeeeees yyyyyyyyyyyyy—"

I woke up from sedation for the third time in as many days, to a familiar, welcoming face. Twilight Sparkle loomed above me and held my good forehoof gently in hers. She'd been crying recently. My right hoof was carefully held in traction and had a thicker cast on it this time. The cast was a midnight blue color, and it looked like there was some silver ink on the front that I couldn't quite make out from this angle. I was sure it was random chance, but it reminded me of Princess Luna. I liked that.

I pushed myself hard to speak, just to get the joke out. "We've got to stop meeting like this," I said. My hoof still hurt, but it was a dull, throbbing ache this time. I reached for what looked like a hoof-held button with my good hoof and pushed it. Sweet, euphoric narcotics flooded my core with warmth.

"I'm so sorry Moonie!" said Twilight as she leaned over and buried her face in the covers. "I know this is all my fault. I was such a foal to do that experiment!"

"Yep," I said, reaching around her with my good foreleg, careful so as not to tangle the IV tube. "I might have done the same, though. There was no way we could have known it would get this crazy. Wait, this is the re-reversed Twilight back from Canterlot, right? I can't see at the moment."

Twilight Sparkle lifted her muzzle up and wiped her eyes, then she levitated my glasses onto my face so I could see her. The stripe was indeed on the correct side of her horn, but she looked totally exhausted. "Past Twilight is halfway back to Canterlot by now, and I was careful to avoid her when I got off the train," she said, then grimaced painfully. "You shouldn't have run! Somehow I knew you were going to anyway."

"No, I should have run. It was the right decision," I said. "And I'd do it again. But, um, please don't make me do it again."

She nodded solemnly, then clenched her jaw. "Moondancer, I didn't want to say this, but we need to pause the experiments," said Twilight.

I winced, but nodded in agreement. "Yeah, I know. It's too dangerous until we have a working theory," I said. "My backers probably aren't going to like this."

Twilight's face hardened. "Don't worry about a thing. I'll stand behind you, and if necessary, I'll get Celestia."

"Thanks. So I guess your polluted biome didn't kill every living thing in Equestria, right? That's a good thing," I said.

Twilight's eyes watered, and once again I regretted sticking my now freshly broken hoof in my stupid mouth.

"Oh gosh I'm sorry, I didn't mean," I said as quickly as possible, which wasn't all that quick given the drugs in my system.

"No, it's okay," said Twilight, and she sniffled a few times while bravely holding back the waterworks. "I didn't stop to think about the consequences of my actions. I put all of Equestria in danger, and even worse I put you in danger. I just happened to luck out."

"It's fine. Nothing bad happened," I said.

"It isn't fine. Between the two of us, I'm the one who deserves to be punished, but you're the pony who's suffering."

"Ugh, give it a rest, Twi. You don't deserve to be 'punished'. Everypony makes mistakes, sometimes even big ones. We didn't know what we were dealing with. I'll live, and my hoof will heal. This mess is behind us, it's over. And as for my supposed suffering, I don't mind being in pain if it's for you," I said. I'd thought I was exaggerating, but to my surprise, I actually meant it.

Twilight smiled and petted my mane, which for some reason felt nice. I didn't understand what she was doing, but it meant something, and it wasn't condescending or mean-spirited. She just wanted to touch me and make me feel better.

"I still wish you hadn't run."

"Are you nuts?" I said, flabbergasted. "You'd want me to let past Twilight die?"

"Moondancer, I don't want you to be hurt because of me! I can't let you sacrifice yourself like this. If something had happened to you, I just..." Twilight's mouth hung open, but she seemed unable to finish the sentence.

I sighed. "Look, for most ponies this is the sort of ethical argument that only comes up in truth-or-dare, but for us it could actually be meaningful someday. If push comes to shove, I would sacrifice my life to save yours, every time. And you should be willing to accept that."

"I can't," said Twilight. She bit her lip.

"If Applejack tried to sacrifice her life to save Equestria, you would stop her?"

Twilight Sparkle looked down at the floor and said nothing.

"Don't play with me, Twilight. Answer the question."

"No. I wouldn't stop her," she said softly.

"And would you order her to her death if it would save Equestria?" I asked.

Twilight shut her eyes tightly and turned her tail on me. "I don't even want to think about this!"

"You need to, at least this once. I want us both to be able to make the right decisions in the heat of the moment."

With her rump still facing me, Twilight spoke, "Yes, I would order Applejack to her death to save Equestria. But only if there were no other choice, and only because I know that's exactly what Applejack would want me to do."

"Well, that's what I want, too. So now you know. If a choice comes down to the fate of Equestria or Moondancer, you'd damn well better be ready to choose Equestria."

Twilight turned back around. Her facial features sported a strange mix of anger and pain. "Why are you doing this to me?"

I sighed. "Because I care about you. Look, we don't need to have a lopsided relationship, but you're crazy if you think that my life is more important than everypony else's. I don't even know you half as well as your best friends from Ponyville, yet you're treating me like there's something special about me. I don't understand what's going through your head."

"Moondancer, we're more than just friends," Twilight said, very quietly. "Are—aren't we?" She looked at me with vulnerable eyes. I really didn't understand.

"Well, yeah, of course. We're partners in science," I said, which was the only thing I could think of to say.

"Oh," said Twilight. Her face fell, and I immediately felt I had done something wrong.

I took a deep breath and tried to center myself. "Look Twilight, I don't want you to feel like you're being punished. But just this once, I need you to promise me you'll put Equestria's needs before mine from now on," I said. "I'm worried about your judgment with this strange way you're treating me."

Twilight closed her eyes. "I promise," she whispered.

"Do the Pinkie kind," I added, as gently as possible.

Her eyes teared up. "I guess this is my punishment, then? I can't say I don't deserve it. Yes, Moondancer. I Pinkie Pie Swear that I will put the fate of Equestria above yours," she said, her voice cracking. She made the motions half-heartedly with her forehooves.

I reached up and tugged at her shoulder. "Thank you. Now come here," I said, and pulled her into a hug as she cried into my vomit-stained mane. I didn't really know what to say, so I just let her lean on top of me for a few minutes as I stroked her back with my left forehoof.

When Twilight finally stood back up, she still looked terribly distraught. She had to reach for some tissues to dry her eyes. I felt really bad for her, but I didn't understand where any of these emotions were coming from. I figured she just felt guilty for my hoof, but that didn't make much sense.

"It's okay, Twi. It's all over," I said, and tried my best to smile.

"I guess," she whispered.

"Anyway, did you want to talk about the experiments? I figure you've had roughly one backwards day longer than I have to think about the situation, plus my surgery downtime and the trip back to Canterlot," I said. I felt uncomfortable about Twilight's mood, so I wasn't really in the spirits for talking shop. I only asked because I hoped the distraction would make my friend feel better.

Twilight nodded and blotted her eyes one last time with the tissues. "The experiments, right. Okay. Well, you were right, we lucked out with my biome. I put together a spell that can detect the reversed organisms, and they can't survive in this environment," she said. "I'm not sure why they die off so quickly, to be honest, but if they didn't I'd have left a trail of microbes everywhere I went. I can detect the trail, but virtually none of it is living."

"We should probably take the time to scour Equestria and remove all traces," I said. "Having reversed DNA and RNA floating about might be dangerous in some way we can't presently foresee."

"I know. I've already informed Princess Celestia of the situation and she's putting together a task force. She wants to know more about what we're doing, though, and I said I'd talk to her after I spoke with you first," said Twilight.

I rolled my eyes. "Buck. Well, as long as she can keep a secret, I suppose she's the best pony to know about all this. Do you think she'll shut us down?"

Twilight shook her head. "I don't think so. Even after what happened she's still supplying steady magilectric power to the lab, for what that's worth. Also, something mildly disturbing came up when I spoke to her."

"Uh-oh."

"She knows what time travel of the third form is, and she refuses to tell me," said Twilight. "She told me that Star Swirl forbade even private discussion of it, but she apparently trusts you and I to keep whatever we discover a secret. If we have discovered time travel of the third form, you might not be able to publish. We'd have to go through Celestia first."

I frowned. "Well, that sucks. But I guess it's for the best. Either way I need some time to theorize about what our research is doing, because I'm stumped."

"Me too," said Twilight, shrugging. "I've been thinking about it for the past day and a half, and I'm still in the dark. The parity shift doesn't make sense, and the disappearance of the antimatter even less so."

"I may be able to partially explain the parity shift," I said, unable to stop a grin from creeping across one side of my muzzle. "Here's a hint. The chirality shift should have affected the particles themselves, too. That means there are zillions of particles with reversed angular momentum."

"You mean like electrons?" asked Twilight. "Electrons can have either positive or negative spin, so there shouldn't be a big difference if they get flipped. The universe might be off by a few in one direction or the other, I suppose."

"No. I mean composite particles which are also fermions, like protons and neutrons. Those particles actually have a hoofedness to them. If they're reflected, they'll behave in a very similar way but with one caveat. Weak interactions, which cause nuclear radioactivity, are known to violate charge combined with parity in special cases," I explained. "Combined CP-symmetry is violated in certain particle decay paths. It's part of the reason the universe prefers matter to antimatter as time moves forward, as we talked about earlier."

Twilight nodded. "Fascinating.... so you're saying that by moving back and forth between matter and antimatter, some kind of weak force interaction is causing the parity of everything in the chamber to flip?"

I shook my head. "Not quite. I can't explain why it happens yet. But there is an inherent asymmetry between matter and antimatter due to weak CP-violations. The neat thing about this is what we can prove if we analyze some flipped matter in a particle bangbox," I said, now grinning from ear to ear. "Do you see where I'm going with this?"

For a moment, Twilight Sparkle stood in thought. I could see the wheels turning behind those beautiful purple eyes of hers. It was funny, I'd never really noticed a pony's eye color before. I realized I'd had a lot of experience looking into hers lately.

"Oh!" said Twilight, her face suddenly lighting up with all the intensity of a brush fire. "If you're right, and the particles themselves have reversed angular momentum—or parity, I know these are the wrong words but whatever—that would confirm several potential theories of particle supersymmetry!" She squealed like a little filly.

I smiled up at her. "I love seeing how much you enjoy discovering new things. I'm lucky to have a friend like you that I can relate to."

Twilight blushed and smiled, then a hint of sadness crept back into those otherwise-pretty eyes. I wondered if she still felt guilty about my hoof.

At some point the doctor had apparently walked into the room. Neither one of us noticed until she loudly cleared her throat.

"A-hem. Glad to see you're up, Ms. Moondancer. We'll need to keep you another four hours, and then you should be able to leave provided the Princess will take responsibility for your care," said the doctor. "You'll need to follow up on a weekly basis with your local hospital."

"I figured as much. So how bad is it?" I asked.

The doctor frowned for a brief moment. "You'll be fine, but it's not pretty. I'm an experienced surgeon, and even I don't enjoy looking at a hoof in this much distress. We had to remove most of the keratin around the entire hoof, and use a mechanical approach to set the coffin bone. There are two metal insertions we're using to hold the bone together. One of them is permanent," she said. "But in the long run it will make the hoof stronger than it was initially, ironically. You'll be on antibiotics for the first two months. The pharmacy here has three prescriptions for you, ready for pickup."

I looked over at Twilight and saw that she was tearing up again. "Stop that," I said, tapping her gently on the cheek with my left hoof. "You're too pretty to ruin that face with ridiculous amounts of guilt. I'm fine."

The doctor nodded. "Moondancer will be fine, Princess, provided she makes her hospital appointments. The plastic sheaths that protect her hoof will need to be changed weekly to make way for new keratin. Ms. Moondancer, you'll need a hoof-wheel to walk until you're fully healed, and don't try to use manumancy or do any flexing with that hoof in the meantime."

"Thank you so much, doctor," said Twilight, trying not to make eye contact with either of us.

The doctor smiled wryly. "Well, since you've required my staff to maintain silence on the chirality reversal, everything about this recent emergency is strictly between us. But I'm not above giving doctor's orders, so be more careful with those science experiments, okay? Hooves are very important parts of a horse," she said, then hoofed me a pen and a clipboard. "Moondancer, could I get you to sign this release? This will let us send your medical records to Canterlot General."

"Sure," I said. I took the pen and clipboard with my magic, signed, and returned them to her.

Then she winged Twilight a silver marker. "Applejack needed to return to Ponyville, so she signed the patient's cast as soon as she got out of surgery. I figured you might want to sign as well, Princess, given that your doppleganger apparently left here without knowing Moondancer was still in our care. Either way, you can keep the marker. I'll, um, just leave you two alone," she said, then walked briskly out.

"Seriously, Twi. Stop beating yourself up over this," I said.

"Right, you're right. I'm just glad you're okay," she said, then moved to the other side of the bed to sign my cast.

I watched her move, admiring her musculature. She's more fit than I am, probably because she has to save the world every other week. She walked up to the cast and looked at what Applejack had written. Of course, I hadn't read it yet. Twilight's eyes widened and she blushed.

"What is it?" I asked.

"N—nothing," she said. Twilight carefully guided the pen to my cast with her magic, then paused and took it into her right hoof instead. I guessed she wanted to practice her hoofwriting with my cast, which I didn't mind as long as it was legible. I assumed as a princess she probably had good hoofwriting and mouthwriting skills as well as her expected expertise with TK-writing, given that she was raised as a unicorn and studied magic at a very early age. (Maybe not wingwriting, but her wings were relatively new—and that's more of a parlor trick than a useful skill, anyway.) Twilight wrote something in roughly the same place where Applejack had, then set the pen back down. "I need to sit and rest for a little bit, if that's okay," she said.

"Not a problem," I said, and smiled. "I need to rest too, and we'll be together for the trip back. Take as much time as you need."

"Thanks," said Twilight. She still sounded glum. I was starting to worry about her. Had I pushed her too hard? I regretted it, but I still figured it was still for the best. She sat down in a chair in the room and immediately dozed off. I realized she'd probably been awake for nearly two days straight if she hadn't napped in the chamber, and it made sense she wouldn't have.

As Twilight began to saw logs with the fervor of a lumberjack, I grew increasingly curious about what she had written. Too curious. I certainly wouldn't wake her up by looking...

I used magic to lift the restraint and pilot my hoof through the air. There wasn't much slack so it was slow and difficult, and it hurt a little to do it. Once out of the sling, I gently lowered the cast and craned my head to look it it.

Twilight had written, "To my good friend Moondancer, with whom I look forward to growing, sharing, and learning, into the future," and signed, "(Princess) Twilight Sparkle." I felt my face flush with warmth.

Directly beneath this, Applejack had written, "Best wishes on Twilight & Moondancer growing together in life," and then signed it. Seemed normal enough. Except something wasn't quite right.

A small amount of text had been inked over at the end of Applejack's sentiment (just before her signature), covering a little more space than "in life". I could have ignored that as some kind of mistake, but why would a mistake happen at the end of a dedication, after what she wanted to write had already been written? It couldn't have been a mistake in the signing, because Applejack's signature was much larger than the blotted-out portion.

Something else was strange, too. The ampersand had been seriously screwed up with lots of extra ink. It took me a moment to realize that the symbol had initially been a heart. Applejack had drawn over it, effectively breaking the heart and changing it into an ampersand.

That seemed like an unlikely mistake. Iconographic writing and language writing are processed by different parts of the pony brain. Nopony would likely put a heart down by accident instead of an ampersand, even if they didn't know how to draw an ampersand properly. The longer I looked at it, the more obvious it became: the ampersand had been drawn to cover up the fact that there was a heart there initially!

But why would there even be a heart there in the first place, I wondered? I supposed that friendship could have been a 'heart' thing, but iconographic hearts usually denoted love, as in hearts-and-hooves day. Applejack couldn't think that Twilight and I were...

Could she? We were both mares! I knew that sort of thing could happen, but I had never been in a relationship in my life! I didn't even know what love was supposed to feel like, so I certainly couldn't be in it. Especially when I wasn't a lesbian. I was certain I would know if I were one of those.

Then I realized something else. Twilight took quite a bit of time writing on my cast. She might have changed what Applejack wrote.

I had a sinking feeling in the pit of my stomach. It made much more sense than Applejack changing what she'd written down herself. As I carefully raised my hoof back up and slipped it into the sling, I considered the implications. It probably wasn't a big deal, right? Maybe Twilight had changed it so that I wouldn't be embarrassed. Or, maybe so she wouldn't be embarrassed. I didn't know which possibility was worse. They both felt icky.

Either way, I knew I couldn't bring myself to ask her about it. I tried my best to put it to the back of my mind as I listened to her snoring on the other side of the room.

It didn't work.

The wheel took some getting used to. It was actually three little wheels: two at the tip of the hoof and a smaller stabilizing one in the back. The whole armature strapped firmly around guides in the cast, and had a metal base with a cushion. The wheels were rubber, and the axle had a small clicking mechanism that kept it from moving unless I pushed it somewhat, and required more force to go backwards than forwards. I imagined how it must work with a simple lever and spring system on the inside. I knew there were fancier versions with crystals that could help control movement, but I couldn't imagine blowing bits on something that extravagant when this little thing worked just fine.

I elected to carry my sweater rather than wear it since I still desperately needed to wash after that ordeal. Twilight Sparkle was barely awake when we walked to the train, and she slept again on the train ride back home. Since we left in the early morning, we didn't need an overnight car. Twilight just dozed off with her head in my lap, which I propped up and held with my good hoof. It was nice. She blushed rather fiercely when I had to wake her up.

She clearly wasn't tired when we arrived, but she was very quiet. We didn't speak hardly at all until she dropped me off at her observatory. She walked me inside, and waited until the door had shut before saying anything.

"Okay, safe and sound. I need to go to my guest room at the castle and try to fix my sleeping schedule. Tomorrow I'll come get you, and we can go to the lab and make some decisions about how to proceed with things. I think we may want to leave the lab active so the room on the far right—room three, I mean—"

"Twilight, what's going on?" I asked, interrupting her. "You seem really distant. Did I do something wrong?" I worried that the answer might be a resounding 'yes'.

Twilight gasped. "No! No, no. Oh Moondancer, I'm sorry," she said, then walked up and hugged me. "I just, I don't want to, you know, get in your way or anything."

"We're friends, Twi. I want you in my way. You're being weird, and I can't help you if I don't know what's going on up here," I said, tapping her on the forehead.

"I, I just have some feelings I need to work through, it's not your fault," Twilight said nervously, as she stepped back and broke eye contact with me.

I sighed. "I can tell. Just don't put up any permanent barriers between us, okay? I'm your friend. You can come to me if you want to talk about your feelings. That's what I'm here for."

Twilight looked nervously at her own hooves. "Yeah, you're right. I really should. Look, Moonie, there's some stuff I need to talk about, but it can probably wait until after we've gotten the lab squared away," she said.

"That's fair," I said with a deep air of resignation. Honestly, though, I wanted the talking to happen now. I almost began to look forward to shutting down the lab.

"It'll be okay. I won't lock you out forever," she promised, hugging me again. "We'll talk more soon. For now, you should rest."

Twilight left. I showered with a plastic bag tied around the cast, though I also used telekinesis to deflect any water from getting near it. It took three shampooings to get the filth out of my mane, and I briefly wondered how Twilight had managed to withstand the smell.

After a light snack, I brushed my teeth, took an antibiotic, a pain pill, and an anti-anxiety med, and then carefully settled myself into Twilight's bed. I knew it was just my imagination since she hadn't slept here in years, but my brain convinced me that the bedding smelled vaguely like her, and it was a deep comfort. I wanted to surround myself with Twilight Sparkle. I didn't want her to be sleeping in the castle when I was here. But I wanted the Twilight around me to be a happy Twilight. I resolved I would find a way. I couldn't stop thinking about her. I needed my friend to know how much I cared about her, and I needed her to feel loved.

Platonically, of course.

Kiss and Tell

I awoke to the sensation of pressure on my chest and raindrops on my face. I struggled in vain to move my legs. I opened my eyes. It was still night. Somepony was lying on my barrel, immobilizing me.

That somepony was Twilight Sparkle. She was crying uncontrollably. She gasped for breath over and over, hunched atop me and shaking.

"Twilight? What?" I mumbled. I tried to reach for my glasses, but she held my good hoof down. "What, what in Equestria is wrong?"

"I'm the worst friend in history!" she bawled between deep, sobbing gasps. "I'm TERRIBLE!"

"Don't be ridic—wait, have you been drinking?" Yes, she had. Her breath positively reeked of ethanol, without the usual apple or grape scents that accompanied pleasant drinks like wine or cider. It was moonshine or vodka, in all likelihood. The hard stuff.

"It doesn't matter, nothing matters," she choked, laying her head on my shoulder. "Oh Dear Celestia, I, I..."

"Twilight, I'm worried. What happened? Is this about yesterday?" I was starting to panic. I couldn't move with her on top of me, and I wasn't about to push her away. I didn't have any idea what to do. I wasn't the Princess of Friendship. I barely knew anything about comforting other ponies.

She snorted and swallowed, then leaned in until our muzzles touched. I could see her eyes clearly. They were red, swollen, and recessed. Tears trickled down the bridge of her muzzle and up mine. And then it happened.

Twilight Sparkle kissed me, right on the lips.

It was rough at first, so rough I didn't know what was happening. But then she relaxed, and I could feel the gentle touch of her quivering lips buffeting mine. Her alcohol-polluted mouth was overwhelmingly soft. I didn't understand anything anymore, but my heart pounded in my chest like a jackhammer. I reached around her with my good hoof to hold her because I didn't know what else to do. Was she taking advantage of me? Was I taking advantage of her? Did this mean something?

Did I actually feel what I was feeling?

She pulled back from the kiss and closed her eyes tightly as though in great pain.

I panted softly, uncertain of what to say. I should have been figuring out what was wrong with her, but I was so distracted by what had happened that I just said the first thing that came to my mind.

"That... was my first kiss," I said.

Twilight nodded, her face contorted in a mask of agony.

"Was it yours?" I asked her, stupidly. "I think you said you hadn't been kissed..."

She shook her head. "Tack, tock—technically no," she croaked, in a voice that was as broken and hollow as it was quiet.

"Oh. Okay, that's okay. Shit, I don't know why I said that. I, Twilight, I didn't know you felt... I mean, we should really talk—"

"No," she said, and clambered off of the bed, nearly tumbling over in the process. "We can't ever talk about this."

She cantered to the staircase and rolled down it, spinning like a tumbleweed and yelping with each bump. I was worried she might break a leg, but all I could do was try to get out of bed as quickly as possible.

"No, Twilight, wait!" I shouted. It was hard to get out of bed with the cast and the covers in the way. By the time I'd stamped three to the floor and grabbed my glasses, the front door had opened and shut. She was gone.

I screamed profanity at the top of my lungs, knowing full well the guard outside could hear me. I didn't care if we'd just made a scene. My world had peaked and shattered all at the same moment.

"IT ISN'T FAIR!" I shouted, grabbing a pillow and throwing it over the balcony, where it ricocheted off of the giant hourglass, tilting it slightly. A bucking princess—why did she have to be a princess? Of course we couldn't talk about this! She didn't want anypony to know. Why would she? I had no right to be this close to her. I was a nobody, obviously not a stallion who could be her prince someday, and maybe not even a good friend. Nothing made sense. Everything hurt.

I grabbed two narcotic pills and a hoofful of benzos. Somehow, I managed enough horse sense to keep myself from downing the whole bottle. I cried into the bedcovers until the pills pulled me under.

"M—Moondancer, are you okay?" I felt somepony prodding me.

I slowly opened my eyes and turned over in bed. My eyes were still wet. I hadn't been asleep long enough for them to dry, or else I'd been crying in my sleep. The pills were in full effect. I couldn't tell how much time had passed: it could have been fifteen minutes, or four hours. But it was dawn outside now, and Twilight was clearly more sober, so I assumed it was hours. Everything around me felt numb and dreamy, and I was woozy. I had taken too much of the medication, but I didn't care at the moment. I felt disconnected from my heart, and that's exactly what I'd wanted.

I grabbed my glasses and looked up at Twilight. She'd cleaned herself up, more or less. Her mane was brushed and her eyes were only a little red now. Her breath smelled like mouthwash. Lines of worry cut into her face, and she fidgeted from hoof to hoof. I didn't envy her. I was grateful I had the pills to help me manage my own feelings.

"Sorry, pills, hard to think..." I said, struggling to get the words out. "You gonna try to kiss me or something?"

Twilight blushed and broke eye contact. She took a nervous, empty swallow of air. "Wait, Moondancer, I... Look, I hope you're not upset or anything, after everything we—I mean, you—went through, um, yesterday," she said. "I'm sorry. I'm sorry about all of it. I'm a little emotional right now."

"Could have fooled me," I said, with as much biting sarcasm as I could muster. She visibly winced, and I felt bad about it. But the pills took the edge off of that, too. I began strapping my wheel on.

"Okay, I guess I deserve that," she said, and stared down at the floor. "Can we just, you know, put everything behind us and have a fresh start today? As friends?" she asked, then looked up to me with pathetic eyes.

All I could feel was numbness and nausea. "Yeah, that's fine," I mumbled, and nodded. She breathed a sigh of relief, but the tension remained in her face.

I didn't want her to know I was incapacitated by a drug overdose, so I navigated the staircase very slowly. Idly, I realized that Dodge City is more liberal with medication than Canterlot. I'd never have received a prescription for painkillers and anti-anxiety meds concurrently here. Maybe the doctor was trying to make a good showing of how she treated the Princess's friend. I resolved to flush the benzos down the toilet later, but I put the pain pills in my saddlebags.

"Oh! Be careful with that hoof, heh," she said, keeping one step behind me the entire way. I felt fortunate I could pass off the dizziness as a mixture of tiredness with limited walking ability.

I stretched a little at the bottom of the stairs. I felt like I might emesis at any time, but I didn't care. I just wanted to get everything over with so I didn't have to think about Twilight for a while. Maybe we just needed some time apart, or something. I didn't know. I felt so numb. I was trying not to think about this—thing between us, whatever it was.

"Mooni—um, I mean, Moondancer, you sure you're okay?" asked Twilight. "You look pretty awful."

I furrowed my brow and looked at Twilight Sparkle. She seemed concerned for me, but it was obvious she was projecting her own issues onto me subconsciously. She wasn't okay inside, so as a psychological defensive mechanism she saw me as not being okay.

Although I probably did look kind of awful, I realized. I'd gone through a huge ordeal the previous day, and that awful nightmare of breaking my hoof and barely saving the bag had been a drop in the bucket compared to the five minutes of overpowering emotional angst I'd endured in the middle of the night. Still, I knew Twilight was far less stable than I was at the moment, even if she hid it well.

A little too well, I thought. She'd been very drunk... I had never drunk alcohol of any sort, but I'd heard it can mess with your memories. Was it really possible? I had no choice but to ask.

"Twilight, do you remember what happened last night?"

She looked surprised. "I, well, I dropped you off here and then I went back to the castle," she said.

"And you drank a lot?"

Her cheeks flushed red beneath that purple pelt. "Well... yes. I wouldn't say it was a lot, but enough to put my sleeping schedule back on track. The alcohol and the pills..."

I planted my hoof over my face. "You took sleeping pills with alcohol?" I said. "Twilight, you could have killed yourself."

I felt guilty for leveling the accusation, because I'd come uncomfortably close to killing myself with pills the previous night. Maybe I was the one who was projecting.

Twilight Sparkle shook her head. "No! I didn't take that much! It knocked me out quicker than I'd anticipated, but—" she started, then gasped. "Wait, how do you know I was drink—Moondancer, did, did something happen?" she asked, and her hoof trembled in the air.

I closed my eyes to stop the room from spinning. What had happened had already happened, and I knew it was going to hurt for a long time. But if Twilight couldn't even remember the drunken kiss, it wouldn't be fair to tell her about it. Maybe someday, if things warmed up between us again, I'd tell her the story. But I wasn't ready to do it that morning. I didn't want her to hurt the way I hurt, and I didn't want to know how she really felt. So, I lied.

"No, nothing," I mumbled, opening my eyes. "I can just smell the alcohol on your breath. I'm glad you're okay."

Twilight breathed a huge sigh of relief. "Oh thank goodness," she said, then I saw her jaw clench. "But if anything about yesterday bothered you, um, I'm here if you need to talk, okay? I can understand if you're upset with me because I haven't been expressing myself prop—"

"Shut up, doofus," I said, and pulled her into a hug. I fought to hold back tears, and I won. Thank Celestia for the pills, I thought. I didn't understand any of these emotions, but I knew I needed to keep them at bay.

Maybe I was a lesbian? It wasn't about sex or anything like that. I'd never even imagined being intimate with another mare before. I just cared about Twilight so much. It didn't matter that she was a girl. I found myself wishing I was a stallion, and thoughts of her body entered my mind. It was very disturbing. I bit down hard on my tongue to distract myself.

"Are you sure you're okay?" Twilight said, breaking the hug.

I sucked at the blood on the side of my tongue. "Yeah, I'll just, brush my mane and teeth, and get some coffee," I said, the words coming out slowly. "Then I can go get the financial information from the lab, because you'll need that if we're going to shut everything down."

"I'll... wait outside," said Twilight, and she nervously left the building.

Ten minutes later we were walking to the lab. I still felt like I was going to be sick, but at least I wasn't dizzy. I opted to go nude while Twilight's washing machine cleaned the sand out of my sweater.

"I may have taken too much medication last night," I admitted. "I'm dealing with some weird emotions..." I immediately regretted opening up, and my voice trailed off.

"Well, weird can be okay," said Twilight, laughing nervously. "I have some, you know, emotions too. And I really like spending time with you. I mean, I really, really do. I just, I don't totally know what you're feeling."

"I feel like I'm going to throw up, but it's just the pills," I said, but I wasn't certain that the pills were the only thing making me feel that way. "I like spending time with you too. I'll always be there for you, but only if that's what you really want, or whatever. Sorry, I'm out of it."

Twilight nodded. "Yes, yes. It's okay. We can sit down and talk more later. This is good, though. I feel better," she said. She seemed to relax a lot. I was grateful for it, too. I didn't like seeing Twilight all wound up. I wanted to make her happy by being there for her, but I didn't know how to go about that. Giving her as much space as she needed seemed like the correct option, but there was a storm brewing in my gut and I had no prior experience managing all of these weird emotions.

Secretly, I was worried that on some level she hated me. I realized that was silly, but if I'd made her feel... romantic... and she didn't want to feel like that, I couldn't blame her for getting mad at me. Maybe it was my fault? I had no idea. My head was spinning, and I didn't know what to think.

We didn't talk any more until we reached the lab. Twilight keyed us in, and when we closed the door I sat on the cool flooring and sighed deeply.

"Moonie, are you sure you're okay?" said Twilight, sitting down beside me. There was that word again, but now it made me feel icky inside.

I gave up. "Okay, well... Something did happen last night, Twi. You were drunk and you visited me, and you were crying and emotional and you ended up running away from me," I said. "It kind of shook me up. But you seem better now, so I dunno. I guess you're fine. I just don't know what to think or feel. I'll feel better when some of these drugs leave my system. I'm starting to wake up, at least."

Twilight gasped. "Oh no! I've never blacked out drunk before... I just assumed I passed out in my bed!" said Twilight. "I didn't have enough alcohol, so it must have been the synergistic effect with the hypnotics I took. I haven't been a somnambulist since I was seven. I'm so sorry, Moondancer, oh Celestia please tell me I didn't hurt you," she said, barely holding back the waterworks. It looked like last night was going to happen all over again, minus the kiss, of course.

I opened my eyes as wide as I could and straightened my back. I realized it was my responsibility to be the strong one this time. I accepted that as a friend's price. "It's okay, Twi. We can forget the kiss ever happened, and move forward."

Twilight blushed and opened her mouth to say something, then shut it again. She seemed very sad all of a sudden. Did I not mention the kiss before? I was so bad at this kind of thing, and while the drugs helped my spirits, they made conversation even harder.

"Right," she said very softly, and took a deep breath. "Anyway, let's, um, focus on our work here. You had financials to show me?"

I nodded, stood up, and walked to the desk, equally eager to talk about something else. "Yeah, here. This is the offer letter, and it's the only thing they've ever sent me. Payment comes monthly via wire transfer. I sent them an initial response with a budget and two follow-up reports, one when the lab was almost completed when I turned on the juice, and a second one just before we started doing experiments together. I never mentioned the mystery mare to them. I figured that should remain a secret until I had more data."

Twilight paused in thought, then placed the offer letter back on the table, unread. "I may have an idea," she said.

"I'm all ears. Figuratively, of course."

"Moonie, maybe the mare in the image isn't Starlight at all. It could be one of us instead! We've never used room three, so one of us could go back in time to the very beginning and do the sabotage," she said.

"Right. I'd considered that, but I don't understand why we'd want to," I said.

"This is what the book meant about exploiting time travel of the first form," said Twilight. "If one of us goes back in time, there doesn't need to be a Starlight Glimmer at all. Completing the circle would make it our fault all along, which is much less dangerous than having Starlight involved."

I shook my head. "But we already know the antimatter chambers don't cause time travel of the first form. It won't work."

"It might, though?"

"No. Move subjective time backwards through all the loops. If it isn't perfect symmetry—"

"Which it isn't," admitted Twilight.

"—then it can't go back forever. There has to be an initial state that began the loop for the first time."

"Are you sure?" she asked.

"Perturbative theory," I said. "Probability approaches one the further back you go in the loops, if only due to random quantum events. Every loop we trace back has a nonzero chance of being the first, and that adds up to impossibility as you approach infinity. There must have been a universe that started this mess, but it wasn't ours."

"Damn. You're absolutely right," said Twilight. "There would need to be a reason for one of us to have gone back in time and sabotaged the equipment, even though the equipment hadn't been sabotaged previously... I can't think of a reason, but it still might have happened, right? Maybe the first time, we sabotaged it to prevent—"

"It probably would have been me, the first time, because I wasn't planning to involve you until the sabotage happened. And I surely would have known that breaking one room wasn't going to stop myself," I said.

"There are too many unknowns," said Twilight. "Even if we could look at every loop in detail, there's no way to perfectly predict the previous sequence of events. The looping could have started from a practically infinite number of situations. Hypothesizing is useless."

I nodded. "True. Every time we open a door, pretty much anything could come out. There's no way to know in advance. But even if we're tapping into a different universe or something like that, that lack of knowledge violates fundamental laws of determinism, and that shouldn't be possible."

"I've been thinking about that," said Twilight. "I need to do some more research, but I have suspicions about what will happen if we attempt to create a paradox. I'd like to sit down with you and go over it later."

"Yeah, let's save the shop talk until we're both totally sober," I said in agreement. "So, the financials?"

Twilight levitated the letter and read it quietly.

Dear Ms. Moondancer:

I am a well-connected mare with a personal interest in funding scientific research on antimatter. I have been made aware that you're interested in doing a large-scale antimatter experiment, and I'm willing to stake a considerable amount of money in supporting you. All that I ask in return is a mention of my contributions in any resulting publications, and access to the raw data at my request.

You will find I have already wired you one million bits. Your reputation as a researcher is strong enough that I have no fears about how wisely you will use the money. Please keep an account of all transactions and report them quarterly, with updates on your progress. I realize this is a large quantity of bits I'm investing, but in time, I'm sure we'll both get the interest we deserve from our exchange.

Yours in discovery,

–CP

Twilight's jaw dropped. "Wait, what?!"

I nodded. "Yeah. A million bits, just like that. In my personal account, actually. I set up a separate account and transferred the money there, then told my backers to use that one instead."

"Moondancer, exactly who is financing you?"

"I have no idea," I said.

"WHAT? You're taking millions of bits from an unknown source? That's, that's just crazy!"

"Oh, come on! I'd be crazy not to take it. I mean, it's research funding. I'm not going to look them in the mouth! It's not like I'm using the money to run for Mayor of Canterlot or something," I said.

Twilight set down the letter and held her hoof over her face. "Oh Moonie. This could be very, very dangerous. You have no idea who we're dealing with."

I shrugged. "Again, I couldn't say no to that offer. They'd wired me the first million before I had a chance to ask questions."

"So, did you?" asked Twilight, with incredulity spread across her face.

"I sent a small message back to them through the bank asking about the details, yes. They've never replied to anything I've sent, except that they adjust the money they pump me based on what I tell them I need. It's a pretty one-sided relationship. You can't blame me, can you?" I asked, frustrated.

"No, but this raises so many red flags! Celestia must know who it is, because any amount over ten thousand—"

"She knows about the transactions, but I don't know if she can trace the source. They're anonymous wires through Manehattan, and the bank guards the privacy of its clients by destroying records after each transfer."

Twilight sat on the floor. "This is unbelievable. Is there a return address?"

"Nope. It's postmarked in Manehattan, but that's all I know. Just one letter, and tons of bits," I said.

"See Pee. Who could CP be...?" Twilight asked the floor. "There must be a wealthy investor, or science foundation, or something."

I reached down and petted Twilight's mane, without even realizing I was doing it. "I tried to figure it out, but there aren't any famous CP's in Manehattan to my knowledge. I only spent a few hours in the library checking, but still. Definitely no major corporations or CEO's, at least not among companies based in Manehattan with that quantity of bits to spill."

Twilight stood up. "Come with me for a moment. I have an idea for an experiment. We can prove this isn't time travel of the first form, and unravel how it works, but I'll need you to follow my instructions to the letter."

"I figured more shenanigans. You know damn well you're not permitted to set hoof in those chambers anymore, princess doof," I teased.

"I know! It will only require a household item. Maybe the bat," she said, motioning to the club.

"Lead the way," I said, levitating the bat as Twilight opened the door to the experiment anteroom.

Twilight promptly screamed and collapsed just inside the room. I dropped the bat and ran into the room, cursing the slight reaction delay caused by the drugs. And then, I saw it too.

It's strange seeing yourself on film, or hearing your voice. It always sounds and looks awful and bizarre, because it doesn't match how you view yourself. But how could it? Nopony knows what they really move like or sound like, because we don't watch ourselves from outside our bodies, unless you're a performing artist or something where you have to see the end results of your work as part of the job.

Well, it's even stranger to see yourself in real life. This is especially true when the other 'you' is lying motionless with a massive-looking closed head injury matting her mane dark from all the dried blood spilled out and onto the floor.

Enter Starlight

I froze alongside Twilight, but unlike her I didn't scream. Internally, this surprised me. It's frightening enough to see an injured pony where you don't expect to find one, much less a dead body, much less your own dead body. I figured something about the impossibility of it all protected me psychologically.

The most unsettling thing was that the body resembled me at that exact moment, minus the saddlebags. My body was nude (also without the sweater) except for the cast and rollers strapped on hoof. The cast was on the wrong foot, presumably because my parity had shifted. The backwards writing on the cast supported that theory. My glasses were dangling off of my muzzle. All of the chamber doors were currently shut.

My ears began ringing and I realized my norepinephrine was surging. I started walking forward. I deduced my unconscious mind was pushing me into danger to protect the princess on my right flank. Mentally detached from the situation, I observed myself calmly approaching my own body to inspect it.

"MOONDANCER!" Twilight shouted, after a delay. "You have to get out of here!"

"I'm fine, Twi. I'm right here," I said casually, inspecting my other self. (It took me a moment to realize I'd accidentally just made a very dark joke, but I was too disturbed by the present situation to correct myself—I elected to assume Twi would realize it was unintentional.) I poked experimentally at my bloodied mane with a hoof, half-expecting it to be a mirage. Closed head injury just behind the horn, an obvious goose-egg of swelling covered by matted hair. Nothing too gory apart from the blood, but any concussion can be deadly. The mane covered up any visible tearing of flesh, but the skull didn't show obvious signs of fracture (at least).

At first I wondered if this was enough blood to "empty" me. It certainly looked like a lot of blood, but a little blood looks like a lot of blood, so I couldn't tell. The fluids had soaked into my mane and dried in small puddles on the floor. My pelt was crusty from it. Everything smelled coppery. I speculated the components of blood having that scent must be achiral. Was it just the iron in the hemoglobin, I wondered? I wasn't sure. The chirality of common scents associated with injury went beyond my current knowledge of pony biology.

"Oh Celestia, we—we have to get you, I mean her, to the hospital!" said Twilight, behind me. I could hear her hooves scrabbling against the metal beneath her as she (presumably) tried to stand up on shaky legs.

I reached under the other Moondancer's foreleg and lifted upward. The front of the body rose like a rigid statue. I was surprisingly heavy, I thought.

"No, we don't. It's already in rigor," I pointed out. I briefly wondered why I had referred to myself as an 'it', but put that in the back of my mind as I set my other self back onto the floor.

Twilight had recovered enough to grab me by the shoulders. "We have to shut the lab down, now," she said. I turned to look at her. She was crying and her forehooves shivered as though she were freezing.

"Obviously. Wait, can you cast the spell?" I asked her.

"What spell?" asked Twilight.

"You know, that spell that lets you view the last few days of a corpse's life as though you're reading a story, remember? The one you were working on?" I said.

"No, no... I haven't finished it yet. We need to get you to the hospital," she repeated.

I turned and looked at the body. It was hurting Twilight, just by being there, even though I was standing here perfectly healthy and safe by her side. I hated this Moondancer for harming my friend. Worse yet, Twilight really wasn't being entirely rational about this whole "dead me" thing.

"Rigor mortis, Twilight! Rigor," I pointed out with another lift of my leg, the rigid body tilting like a pewter figurine. I was starting to feel very angry and I didn't know why. "We can't have two Moondance—no. Twilight, open room one."

"We're leaving now," said Twilight, tugging weakly at my hips.

"Twi, I'm not leaving until you open room one. Don't make me do it, because if I go into one of those rooms, even by mistake, I could end up being her," I said.

"We're not doing any more experiments!"

"Then open the door. I'm not going inside."

Twilight paused for a moment. "Stand outside the doorway," she ordered, and I stood back in the doorway of the anteroom. She trotted over and opened room one, ratcheting the door over the stopper apparatus. The room was empty, as I'd anticipated.

"Watch your flank," I said, as I remotely levitated my lifeless carcass and slid it across the floor with a strong telekinetic shove. I had to use sufficient force to get it past the magic barrier, but the lip on the doorways was negligible.

"Moondancer, wait!" said Twilight, but it was already too late. My body scrunched oddly up into place and then everything disappeared. I held onto the doorway easily, while Twilight slipped halfway into the room from the vacuum pressure. She scrambled back out of the chamber moments later, accidentally sliding the teeth out of the way, and shut the door behind her in the process.

"There," I said. "Now we just have to clean up the blood, and problem solved."

Twilight ran up to me, her muzzle bearing an expression of horror. "Moonie, what did you just do?" she said.

"I disposed of the body," I said. "Look, it's fine. I never liked me anyway," I said, only half-joking.

Twilight Sparkle gave me a strange look, almost like she had no idea who I was. "That was evidence of a murder!" she said. "You just sent evidence of your murder backwards through time!"

"No, I didn't," I said. "Don't you get it yet, Twilight? We're not dealing with time travel of the first or second forms. That wasn't me. That was some other Moondancer from some alternate iteration of this madness. I didn't send it back in time, I sent it to another dimension."

"Wait, what?"

"It's clear what's happening now. Conservation of energy is being violated if the loop isn't perfectly symmetrical, and it isn't. The only way that can be true is if our universe isn't a closed system. Whatever this kind of time travel is, we're connected to other universes in some way we haven't yet been able to interpret. From the perspective of our universe, anything that enters the chamber ceases to exist completely. As far as this world is concerned, each chamber is a disintegrator," I said.

"But why would you do this?" she gasped. "I don't want ANY Moondancer to die!"

"It's too late, Twi! I wanted to get rid of it, okay? Look at you! Look at what it was doing to you!"

"You had no right to—"

"It was my fucking body, Twilight! I had every right!" I shouted.

Twilight looked like she was about to shatter, and I knew I'd gone too far.

"Twi, wait," I said as she pushed past me.

"We have to destroy the lab right now," she said, headed for the stairwell.

I grabbed her from behind, and she fell to the floor and started sobbing. Uncertain of what else to do, I lay there on the floor with her, holding her close. Several minutes passed before she could say anything.

"I can't handle this. I can't handle losing you," she whispered.

I didn't understand this reaction at all. "We've already discussed this, Twilight. Equestria's future takes priority over Moondancer, and we don't know why the other me died yet. I shouldn't be this important to you," I said, and right then I had an idea, one born from the need to escape this awkwardness I felt regarding Twilight Sparkle's attachment to me. "Would you let me do something to help numb your emotions, just so you can think rationally for a moment?"

"I don't want pills," she said softly. "Well... maybe."

"Not pills, but that makes a decent Plan B. It's a spell," I said. "A spell I'm not supposed to know about."

Twilight sighed and sniffled. "Do whatever."

I cast the spell. I'd only ever cast it once before: experimentally, on myself. Twilight sat up and turned to face me. Her face was expressionless, despite the red eyes from crying. She looked disturbingly schizoaffective, and I immediately questioned whether this had been a good idea.

"Moondancer, what did you do to me?" she asked, her voice devoid of passion.

"I temporarily neutralized your emotional state," I said. "More specifically, I've separated your emotional state from your cognition to the point where it won't interfere with your decision-making abilities. I'll write the spell down for you if you need it later."

"This shouldn't be possible," said Twilight. "Wait while I clean myself up." She walked into the bathroom. I grabbed a piece of parchment from the desk and transcribed the spell.

Twilight returned with a washed face which still bore no discernible expression. It was certainly more unnerving to see the effects on another pony than it was to see them on myself, but that's probably because when I'd originally seen the effects on myself (in the mirror) I was under the effect of the spell. I cursed not realizing the existence of that lens. I should have known this spell was more dangerous than it had appeared to me subjectively.

"Maybe this was a bad idea," I said, but I hoofed her the spell anyway.

"I don't understand why I haven't heard of this spell before," said Twilight, almost robotically, as she studied the parchment.

"I think it's proscribed."

"You shouldn't legally be casting it?"

"That's what proscribed means. Actually, I think knowledge of the spell might even be a crime. It's a long story how I found it, but the short version is it was in the Star Swirl the Bearded wing of the Royal Canterlot Library, in an area scheduled to be archived somewhere private. I don't have access to that part of the library, of course, but this was a long time ago when I was visiting with a study group with special permission. When I saw it, I memorized it on the spot before anypony could catch me looking through the materials."

Twilight paused for a moment, calculating. "This is fine. I should have the legal authority to use the spell, and I won't tell Princess Celestia about it for the time being. How long does it last for?"

"From what I understand, it lasts until voluntarily cancelled by the subject, though there's probably a maximum time limit of less than a week. I can attest that it continues to work when you're unconscious," I explained.

"How do you know that?"

"Because I've used it on myself, as an experiment. Only once, though. Um, it was when you missed my birthday party," I said, then looked nervously down at my hooves.

"Oh," said Twilight, flatly.

"I ended up cancelling the spell after about eighteen hours. Waking up without emotional motivation was disturbing enough to give me an indication as to why this spell might be proscribed," I said, hoping Twi would take the hint.

"Well, I believe this is useful. I can think much more clearly," said Twilight. "I'll maintain the effect until we've resolved this issue, then cancel it afterwards."

I sighed. "Okay, fine. So let's destroy the lab so we can get you back to normal."

"No," said Twilight. "We can't destroy the lab yet."

"Wait, what? You were gung-ho on destroying the lab right before I cast the spell!" Oh, horseshit, I thought.

"I know. But with my head clear of these 'feelings' I can see that what you said was correct. There's no reason for me to be concerned about your death because we already know the loops aren't symmetrical," she said. "Currently, room three is serving as a failsafe: it's never been used for an experiment. That means we could send a message backwards through time to the very beginning when you first activated the rooms, and prevent this entire situation from starting. That would almost certainly save our lives in an alternate universe."

"You mean one of us could go back in time to stop it," I said.

"No. That would be unacceptable," said Twilight. "Like you said, from the perspective of our universe, each chamber is a disintegrator. Unless we have proof that a second alive-and-well Twilight or Moondancer currently exists in this dimension, it wouldn't be right to send one of us away from it. Additionally, if the goal is to stop the program entirely, whoever goes back in time would end up being in a universe where there are two copies of that pony, which is far from ideal."

"Look Twi, I was maybe talking out of my mark when I said some of that," I admitted. "Until we have a theory that can predict what comes out of a chamber, we can't assume that dimensional travel is actually happening. There must be a causal connection between this universe and any universe that precedes it, and while I can clearly see the forward link I can't predict the backward one."

"I have a theory about that. I need to do some research to confirm the mathematics will hold, but I should be able to accomplish it by nightfall. If the math checks out, we can run a simple set of experiments with rooms zero or one. Based on the results of those experiments, we can decide whether or not to activate the failsafe."

"But how would we activate the failsafe without using a pony to do it?" I asked.

"Not hard. We can build a robot capable of waiting until the field first turns on, and program it to cause enough damage to draw attention to that room, by either nullifying the field or otherwise affecting the measurements. This would ensure you open room three first, at which point you would find the robot and a written message it carries telling you to destroy the lab," Twilight explained.

"And then after we send that robot, we can destroy the lab in this dimension," I said. "Although I still have no idea how my backer will react."

"Moondancer, you mentioned that you sent messages to your backer, yes?" asked Twilight. "How exactly did you send messages?"

"Oh, right. I do that through the bank," I said. "I would send back one bit by wire transfer to whomever claimed the sender's identity, and include a detailed message with the transaction. Of course, I can't prove the right pony got it, but it's a fair bet that CPXXXXX is unique. Fortunately the bank is cool with it, probably because they're taking a cut of millions of bits in transfer."

"Interesting," said Twilight. "I wonder who CP could be. Celestial Princess? I don't think we should tell Princess Celestia what we know until we have more information. Rarity has a friend and coworker named Coco Pommel in Manehattan, but she wouldn't have access to that kind of funding."

"CP-symmetry breaking?" I asked, raising a brow.

"Implausible," said Twilight. "Why would anypony fund you to do research that they already knew was going to break CP-symmetry?"

"I dunno, just brainstorming here," I admitted.

"Let's break for now. We shouldn't attempt to contact your backer until we know what our full plan of action will be. I'll do research to flesh out my theory on what I assume must be time travel of the third form. If I'm correct, it would make sense that this kind of thing would be forbidden."

"It makes sense that the spell you're under is forbidden, too. I'm worried, Twi. Please don't leave that spell on for long, okay? Emotions can be inconvenient, but they're an important aspect of proper decision-making when it comes to ethical choices and moral consequence," I pointed out.

"Okay. I'll only keep it up for as long as absolutely necessary," said Twilight in a disturbingly flat tone of voice.

Unfortunately, I no longer trusted Twilight's judgment to make that call. Apart from arranging a meeting with Princess Celestia, which neither of us wanted to do at that point, I wasn't left with any safe options. I couldn't force the spell out of her without taking time to engineer a counterspell, and that would take longer than the spell's natural duration. I just had to hope that Twilight would act reasonably.

In the back of my mind, I had this awful feeling that my death no longer mattered to her. Even if it was for the best, I still didn't like it.

On the other hoof, I didn't like myself enough to disagree.

I headed back to Twilight's place to do some research of my own on the dress. This was the only currently parity-flipped object I still had access to, because I didn't know what Twilight had done with the shopping list. I assume she had transcribed the list backwards, probably by writing it down before going back in time again, and taking it with her through the chamber—so the writing would be forwards but the paper reversed. I'd briefly considered stealing other-me's glasses before disintegrating the beast, but I figured (on a primal emotional level, one my friend did not currently possess) that that would have been like beating a dead horse. I might have hated my corpse but it wasn't appropriate for me to use myself as a piñata.

For all I knew, I had used myself as a piñata already, hence the corpse. Who could say? A room where anything can come out is a scary thing to open. I was tempted to destroy the place without Twilight, but I couldn't. Even if she wasn't thinking sanely, we were still a team.

On my way back to the house, I bumped into Twilight's mother, Twilight Velvet. I didn't recognize her until she started talking to me (the family resemblance is pretty strong, fortunately).

"Moondancer? Could I talk with you a moment?" she asked, walking alongside me as I headed toward Twilight's old home with the dress in tow. She had a deep look of worry on her face.

"Yeah, sure. What's up?" I asked, already fearing any answer.

Twilight Velvet reached out and stopped me with a hoof. "It's about Twilight Sparkle. My daughter has been... well, she's been very emotional lately."

"I've noticed," I said, lacking anything not-stupid to say in its place. Granted, the exact opposite was true now, but presumably Velvet was referring to further back than ten minutes ago.

She nodded. "I'm very concerned about her. She's been staying with us rather than at the castle, I presume because she's trying to avoid somepony, possibly Princess Celestia. Originally she was acting so distant emotionally I could hardly recognize her as my daughter, but last night she was drinking, which I've also never known her to do, and crying her eyes out," she said, her voice barely a whisper. "She won't say more than a few words to me about it, and she won't eat dinner with us. She looks very unhealthy. I was tempted to call for a nurse, and I will if she stays with us another night. I was hoping you'd know something about this?"

I winced. "Ah, geez. Yeah, I know she's been going through a lot of stuff lately."

"It isn't my place to get involved," said Twilight Velvet, violating her own logic in the span of a single sentence, "but I know you're close to her. She cares very much for you, Moondancer, and she seems to think she's let you down in some terrible way. She hasn't said anything about it to me, but a mother knows."

I nodded slowly. "Yeah. We've both been kind of emotional lately," I said, trying to straddle the fine line between keeping Sparkle's confidence and helping her cope. "We've been working on some research together and I was injured, which she blames herself for a little, for one. There's... well, more, but it's complicated."

Twilight Velvet tapped a hoof to my muzzle, which irritated me slightly, but I did my best to hide it. "Say no more," she said. "The details aren't important. I just want you to know that your friend is hurting, and anything you can do to alleviate this suffering, perhaps by talking it out with her, would lift a tremendous weight from an old mare's withers." (She didn't look old, but I presumed that was simple self-deprecating exaggeration used to establish rapport within a narrow time-window such as this one.)

I took in a deep breath. "I'll talk to her about it. We've already been talking about her feelings, and she hasn't stopped confiding in me, so I expect things to improve soon," I said, then paused for a moment. "I like her too. Er, as a friend. A good friend, I mean." I felt my cheeks flush.

"Thank you," she said, and she seemed relieved. Then she gave me a hug (before I could protest the physical contact) and trotted off.

Ugh. I did not want to reopen Twilight's wounds anytime soon, but her mom was right. We really needed to talk about a lot of things. The kiss, for one. That conversation was undoubtedly going to suck, but it was a necessary bandage to rip off. At least I could put it off until she recovered from the effects of my spell. Plus, I was pretty sure Twilight told me she was staying at the castle—so was she lying to me, or was she frequenting both her parents' home and the castle? There was no way to know without talking to her.

After I got 'home' (which more and more Twilight's old place was starting to feel like, to me), it took me about a half-hour to relax enough before I could start my research. I was buzzing from my twin overdoses of drugs and emotional pain. After a brief meal and half a pain pill I felt well enough to numb my heart with some serious, sedulous science. The half-hour was enough time to run my sweater through the drier, so I had another warm and psychological comfort to hug me as I worked. I almost felt normal again, excepting the cast.

I tried to take a shortcut to begin with. I was able to modify an existing spell to detect aberrations of intrinsic angular momentum, and I cast it on the dress. Oddly enough, there was no signature. The dress was definitely parity-flipped (it still had the odd scent, or lack thereof). This indicated that either my spell didn't work (a very likely case given the degree of adaptation and lack of testing), or else the parity change extended only to the molecular level.

I assumed that my spell didn't work, because otherwise the result made no sense. If something was parity-flipping the contents of the field between universes, the intrinsic angular momenta of the individual particles would need to be affected. Intrinsic angular momentum is a true parity feature, well-established in physics. The weak force is the only force which breaks parity-symmetry, as well as the only force which breaks CP-symmetry (charge and parity combined). Parity-flipped matter should behave in some fundamental sense "similarly" to antimatter, in that it would be stable, but quantum effects related to nuclear decay would slightly disfavor its production.

So I attempted to confirm my suspicions that the spell was flawed. Fortunately, I had a more scientific method for testing particle parity available to me: a small bangbox I keep with me in my saddlebags. I set the vacuum up, then pressed the hem of the dress against the input terminus of the bangbox in order to feed it atomic material (I could control the input finely enough to ensure it didn't draw in material from the air by mistake). I filtered out everything from the sample except for a hoofful of atoms of radioactive Carbon-14 which were easy enough to rip out of the phospholipid residues in the material.

I considered it unlikely that the electrons in the dress had not largely migrated to surrounding material (although even that is a bizarre thought, because one doesn't normally encounter electrons that differ from one another in any way at all and so there isn't a "this electron" or "that electron" to speak of in the first place). However, the atomic nuclei should have remained consistent even with quantum perturbations in play, as only those perturbations associated with the weak force could cause the particles to flip and (as the name sort of implies) the weak interaction doesn't come up in a constant fashion for stable matter. In particular, I made the assumption that Carbon-14 in the dress was primordial with respect to the dress's manufacture. This is a safe assumption because virtually all Carbon-14 in a common organic material should have been produced by intake of Carbon-14 through the food web, and production would cease afterwards. If those Carbon-14 nuclei had not themselves been produced through nuclear decay of unexpected heavy elements in the dress, they should retain the parity flip at the particle level (even as dynamic of a place that a nucleus is, because none of the strong force interactions which roil the nucleus could affect the parity of its constituent quarks and temporary mesons).

While the theory is far from sacrosanct, it is fully expected that the decay of Carbon-14 is mediated by the weak interaction. This suggests that the decay of a parity-flipped Carbon-14 nucleus would produce the wrong-hoofed fermions (hoofedness being determined by its representation in the Ponicaré group, as evidenced by the 'static' helicity of the particle in a massless frame). This would necessarily leave a telltale signature in the bangbox trace whenever a parity-flipped Carbon-14 atom decayed.

In laypony's terms: if the particles were flipped, rather than just the molecules, radioactive Carbon-14 decays from the dress's atoms would yield a telltale signature in the bangbox.

While I waited for results, I spent a couple of hours researching details on weak symmetry-breaking. I was unable to come up with any theory that would allow for a molecular parity shift without causing a corresponding change to the angular momenta of the atomic nuclei. I was, however, able to determine with high certainty that magic could theoretically be used reverse the parity of a quantity of matter (or antimatter) without affecting the subatomic level (I even had some ideas on how to do this), but this should not be an effect of a field that operated on the individual particles. Unless, that is, somepony cast a parity-reversing spell directly into the field itself, which was clearly an absurd proposition.

Then it finally happened: I caught two Carbon-14 decays. Both of them were completely normal. That was very compelling evidence that the parity of the individual particles hadn't been flipped.

It simply made no sense. There was no way anything in nature could reverse the parity of an object at the chemical level, but not the subatomic level. Only a magic spell could do something like that.

I was sitting on the sofa by the bookcase with several books in my lap, deep in thought when Twilight entered. It was nightfall already, which kind of surprised me (time flies when you're working) but it matched when I'd expected her back.

Right away, I noticed something weird. She was wearing her forelock tied up the same way I do. For a moment I wondered if she were making fun of me, but that seemed highly unlike her. Her face was mostly expressionless, but it was clear to me she didn't have the spell up anymore. Something about her body also seemed "off" to me.

"What's up?" I asked, quickly standing up and spilling books all over the floor in the process.

"Oh, um, not much. So I did my research, and I think we should go destroy the lab right now. There isn't an improved chance of helping another Equestria by sending a message backward," she said.

Twilight was lying. I was terrible at reading ponies, but for some reason I felt a primal connection to her mental state, and I knew her in some deeply intuitive sense. Everything on her face was a red flag. She didn't even look like herself with the forelock tied back. She looked more like a broken version of me, like I was staring blurrily into a mirror with my glasses off.

"Moondancer?" she asked nervously when I didn't respond. I snapped back to reality, but froze. Wasn't Starlight Glimmer a laureate mage?

I turned and pulled a specific book off of the shelf with magic and threw it to her in an underhoof arc. "Here," I said.

"What's this?" she said, catching it deftly in her left hoof. I was more than a little surprised she didn't use magic, but I'd thrown it perfectly to her left flank.

"Read the cover out loud," I ordered. She looked at the book. It was written in Arabic, a language I knew Twilight had studied in school. Even with my limited high-school Arabic knowledge I could read the cover, but you'd need to at least know some Arabic to have a chance (the alphabet is too unusual, by comparison).

"Oh, I'm sorry... my Saddle Arabic is really rusty," she said, grimacing.

"Yeah, right. Read it. Now," I said. I could see perspiration forming on her brow.

"Let's see. This must be '1001 Arabian Nights'?" she said, tilting the book at an angle. It was a reasonable guess. That book was also in this library. But it was a wrong guess. That was the reason I had chosen this book, in particular.

I immediately tossed up a bubble shield around my body. "Who are you, really?" I asked, though I already knew the answer.

Twilight Sparkle looked shocked for several moments, then her face relaxed, and finally broke into a smirk. Her horn flashed, and her wings disappeared. She still looked (and sounded) like Twilight Sparkle wearing her forelock up, but now she appeared to be a normal unicorn. "Oh, Moondancer. Why did you have to give it away so quickly?" she said, her voice dripping with sarcasm. "Now I don't have any reason to let you live."

"You won't be able to break through my shield without effort," I stated. "While you do, I'll cast a spell to magnify my voice and shout for the guard." I wasn't bluffing, but I didn't think I was likely to walk away from this encounter either.

Wingless Twilight sighed and shook her head. "You stupid mare. If I wanted you dead, you'd already be dead. I could destroy that shield in a fraction of a second," she bragged. "I'm actually trying to do you a favor. You've already learned that these time cycles are quirky, to put it mildly. Whatever caused you to go back in time and croak is still a probable future for you. Destroy the lab now and it can't happen. There isn't any other experiment running aside from those four rooms you constructed, minus the one I smashed, because I don't have the funding or magilectric power source to reproduce it—yet. Simply terminating the magilectric flow to those rooms immediately and permanently severs your tie with the past, thereby saving your life."

I paused in thought, clenching my jaw as I maintained my shield at full strength. "If you want the lab destroyed that's all the justification I need to keep it running," I said. "Whatever you're in Canterlot to do can't be good for Equestria."

Twilight rolled her eyes. "Oh spare me. Noble little Moondancer, so eager to sacrifice her life for the betterment of Equestria. Give me a bucking break," she said, and made a gagging motion with one hoof. "You lack the ability to even begin to comprehend the magnitude of what I've had to sacrifice for Equestria."

"You shut up. Twilight's told me all about your scheme for revenge. You're the Starlight Glimmer copy who didn't get reformed," I said, throwing my cards on the table. I had a clever goal in mind, however. Psychologically speaking, the fastest way to extract information from an unwilling target is to tell them information that is possibly false, as they'll have a strong drive to correct you (unless they're a complete psychopath, which I understood Starlight wasn't). For example, if you want to know if somepony is married, the fastest way to find out is not to ask, "Are you married?", which they could choose to rebuff, but, "How's your wife doing?", for which virtually no unmarried pony would reply with anything other than, "I'm not married".

"I don't know what freaky brand of screwed-up mind-altering spell Twilight put on my double to make her give up on her dreams, but it doesn't matter. She isn't going to get the chance to do it to me," she revealed. "You idiots should both know better than to keep an experiment this dangerous running. My only concern is the danger it represents to me personally, but go ahead and kill yourself all over again! See if I give an donkey's ass," she said, with a chuckle.

Then I noticed something. She definitely wasn't a psychopath, because I could tell she was scared. It was very subtle, but I was watching her face like a hawk, and I saw the confidence fade from her eyes at that very moment.

"Are you going to leave, or are we going to do this?" I asked, not at all prepared to 'do this'.

"Like I said. It's your life, or lack thereof," she mumbled, then cast a spell that returned her wings (or removed the illusion of Twilight not having wings, rather—which I assumed was harder to maintain than the magic producing the general disguise). "Be damn sure to tell Twilight I was here, by the way. She'll know exactly what that means." She walked backwards to the doorway and exited, shutting it behind her.

I waited half a minute before dropping the shield and falling onto the sofa, completely exhausted and shaken by the experience. For some reason I wasn't frightened, however. She was right about one thing, after all: with a disguise that convincing, Starlight Glimmer could have easily murdered me without me being aware of it. But for some strange reason, I had a feeling that she was actually afraid of me.

I had to figure out why, before it was too late.

What Are the Odds?

Scarcely ten minutes had passed before the door opened again. As before, there was no warning knock. I nearly jumped out of my pelt (not literally, of course).

It was Twilight Sparkle, but she still had her forelock tied up in the band. At first glance I thought it was Starlight Glimmer returning, but I quickly deduced that Starlight would have been spying on Twilight and would have noticed her wearing her mane that way. It still looked odd, and deep down I feared this was all some sort of a horrid psychological game to make fun of me. I had grown to trust Twilight, but after my encounter with Starlight I didn't know what to expect anymore.

"Moondancer? Is everything alright?" said Twilight. She walked right up next to the enormous hourglass and stood there, watching me from a distance.

"Read the cover of this book, please. It's important," I said, telekinetically tossing her the same book I'd used previously.

Twilight caught the book with her magic and furrowed her brow in apparent confusion as she brought it near. "Okay..." she said, and looked down at the book. Then I noticed something odd: she was pretending to look at the book, but she was actually staring into the hourglass. I realized she was probably watching me in the reflection of the glass. Was this still Starlight Glimmer, I wondered? Or was it just Twilight, acting suspiciously toward my own unusual behavior?

"Al-Risalah... oh wait, this is the Theologus Autodidactus," Twilight finally said. "I forgot I had a copy here. What's this about?"

Twilight's voice was passionate enough that it was clear she didn't have the spell up any longer. Internally, I breathed a sigh of relief.

"Starlight Glimmer was here," I said.

"What?! How did she get in?" asked Twilight, her jaw agape as she walked up to me.

"She disguised herself as you. Perfectly, I might add, including the hair tie you're using now, though at the time I thought she was just mocking me," I said, feeling a bit queasy about the idea. Why would Twilight choose to wear her mane like that? Was it an attempt to be psychosocially endearing to me? I continued, "She wanted to trick me into taking her to the lab and destroying it with her."

Twilight dropped the book on the table beside the sofa. "Well, that cinches it. We need to get you out of Canterlot tonight."

"Wait, what?" I said. "When did this become a plan?"

"I already went out and bought you a train ticket. After cancelling that emotion spell, I realized I didn't want you to be anywhere near the lab until I've short-circuited the system. That way there will be no chance whatsoever of you going back a day and dying," she said. "Here." She handed me a ticket. It was set to leave for Ponyville at midnight.

"What about all the research you were supposed to be doing?" I asked. "Did you come up with anything?"

"Yes, but it's not important right now. I'll walk you to the train, and we can talk along the way," she insisted. There was something rushed and anxious hiding in the timbre of her voice. I didn't know if this was really Twilight or not, but I knew I was being played.

"It's fine," I said. "You go back to the castle. I'll head to the train station after I finish here."

It was hard to see in the dim lighting, but Twilight's face paled. "Look, I really want to make sure..."

"Twilight, I need you to tell me what's going on. That is, if this is even really you," I said, frowning. "You're a terrible liar."

Twilight Sparkle froze for an extended moment, then sighed. "Damn. Still not buying it?" she asked, and with a flash of her horn, her wings had disappeared again, although I could still see a vague outline. She also seemed too thin to be Twilight, as I could see the outline of her ribcage in the dim lighting—she was clearly malnourished, possibly anemic. I was physically too close to prevent her from attacking me, so I decided to lay all of my cards on the table.

"It's obvious by now that you don't want to kill me. What's your deal, Starlight? Why don't you just tell us what you want?" I asked.

She took a deep breath. "Twilight won't listen to reason. She's making a terrible mistake. It would be dangerous for me to approach her, but she'll listen to you."

"Okay. So why should I believe you? I still don't understand your role in any of this," I said, then mentally cursed myself for revealing that lack of knowledge. It was a rookie detective mistake.

"Oh for buck's sake. You've already seen what happens to you, Moon— Moondancer! I'm trying to save your life, you crazy mare! I don't expect you to understand why, but the fate of Equestria is at stake," she said. I noticed her eyes twitch upwards as she said the last bit, a telling indication of an intentional mistruth. She was very nervous about the message she was conveying, and it was seeping unconsciously into her mannerisms.

"Look, I'm not leaving for Ponyville. That's just stupid. If you really have Equestria's interests at heart..."

"I don't, okay! It's selfish," she yelled. "I admit it, what I want is selfish! But it's in your best interests, too. Just leave Canterlot for one day, that's all I ask. Please."

"And leave Twilight here defenseless against you?" I said. "As if."

Twilight's face contorted in frustration, and then her eyes brightened slightly. "Okay, you know what? Fine. Stay here. But you'd damn well better tell Twilight I was here. Tell her I'm waiting for her. Tell her everything we talked about, as soon as you see her. Are you at least smart enough to do that?"

"Well, obviously," I said, rolling my eyes.

"Okay. That... yes, that should be enough. Yes. Tell her I was here. I have to leave now to turn my... to see somepony important," she said, and turned and galloped for the door as her wings flashed back to visibility.

I watched her leave, stunned.

Who the buck was that, I thought? Was this really Starlight Glimmer I was dealing with? I couldn't think of anypony else who could possibly imitate Twilight to that degree, with the obvious yet notable exception of Princess Celestia.

Or could it have been Twilight herself?

If it actually were Twilight Sparkle, she'd lost too much weight in a few short hours—she had to be a copy from another universe. But why the hay would she pretend to be Starlight pretending to be herself? I couldn't believe that any Twilight would lie to me that way, at least not if the emotion spell had finally ended. Whoever it was, they definitely had emotions.

As unlikely as it seemed, a visit from Starlight Glimmer was still the leading theory. I felt like I was missing an obvious clue, though. There was something about the way she looked, but I couldn't quite put my hoof on it.

I came to my senses after a moment, and trotted to the door to see if I could catch which way she went. I was too late. Nopony was outside other than the guard. Day had just recently given way to Night, and Starlight could have cantered behind any number of buildings. I took a few steps out the door to gather my bearings and immediately tripped over some sort of thick branch or something, which was lying right there on the sidewalk. Without looking, I angrily kicked whatever it was into the bushes.

"Are you alright, Miss Moondancer?" asked the guard. He walked over to help me up.

"I'm fine," I said, and sighed as he lifted me up. "Just not liking this rolling cast at the moment. Did you see where Twilight went?" I asked.

"Towards the castle," said the guard, but this was unsurprising information as most of the city lay in that direction.

Feeling defeated after my embarrassing tumble, I went back inside to wait for the 'real' Twilight. I felt lost without her. I didn't have to wait long, however. She arrived within the hour. Unlike the previous intrusions, she knocked before entering.

I knew the moment I saw this Twilight that she was the real deal. She didn't have the stupid hair band on, and her face was totally expressionless. The emotion spell was still up.

"Hello, Moondancer. I have a testable theory," she said as she shut the door behind her with her magic. "Is there anything important to report before I begin?"

I looked into her eyes and felt my heart sink. Starlight really, really wanted me to tell Twilight that she had been here. It seemed clear she'd known what would happen in the future, and she was trying to muck with events that had occurred in the past, undoubtedly to change something. I just had no idea what, or why.

Then I wondered: should I tell Twilight Sparkle the truth about Starlight's visits? Or would that be playing directly into Starlight's hooves? After a brief moment of thought, I determined the answer was yes. I should definitely tell Twilight what had happened. Withholding information wouldn't help us to defeat Starlight. However, I couldn't tell her yet, not while she still had that accursed spell up. I had no idea whether or not Robo-Twi would react sanely to the news that Starlight Glimmer had been here, not to mention the fact that Starlight apparently had the ability to copy Twilight Sparkle almost perfectly.

"Moondancer?" asked Twilight. I realized I'd been staring off into space.

"Oh, sorry. Yeah, something happened, but it's not important," I said. "We can discuss it later, though if you could drop the emotion spell, it would help..."

She shook her head. "No. I'm leaving it up until we shut down the lab, for added safety."

I sighed. Having a spooky emotionless friend didn't feel safe to me, but she was probably right. "Okay then. I'd really like to hear your theory."

Twilight nodded and sat down with me on the couch. "Actually, first I should inform you that I've completed my death spell. I figured it might be useful in the future."

"I'm a little curious how it works," I said. "A lot curious, really."

"It translates the subject's past few days of experiences into a narrative form," she said. "The result of the translation would read just like a story from that pony's perspective, except everything would conspicuously be in the past tense, even the subject's sense of self, since there would be no 'am' or 'is' for the subject anymore."

"That's rather odd. It's too bad you weren't able to cast it on my corpse, although I'd hate to have to do it myself. I'd already know I was doomed before I got to the end of the 'story'," I said.

At that exact moment, I had a very strange feeling of deja vu. I ignored it, as I had never believed that mundane mental phenomena had magical causes. Theories about consciousness being magical were still held by some researchers, but they lacked solid evidence. I had always been a scientist, first and foremost.

"That said, here's the more important news: I'm fairly certain I've figured out time travel of the third form," she said. "I can predict what will come out of the rooms."

"Awesome! I'm all ears. Figuratively speaking, of course."

"Of course." Twilight pulled out a piece of parchment and a quill. "I was concerned about the potential for paradoxes and the overall inability to predict what comes out of the chamber, given that we now know it comes from some other universe we don't have a window into. But I've come up with a way that links the two worlds deterministically."

She drew a line on the parchment, and placed a dot in the middle. "Say this point on our worldline is where and when we initially open a test chamber. What comes out of the chamber," she said, drawing a second dot to the right of the first one, "needs to be predictable in our universe, even if another universe is involved. Otherwise, the two universes couldn't be causally linked in the first place."

"Agreed. I came to a similar conclusion earlier today," I said. "If it's not time travel of the first form, there has to be some hidden causal connection linking the two universes a priori."

"It turns out there is a link, and it's remarkably simple. I realized what it was when I started thinking about attempting paradox experiments," she said.

"Paradox experiments as in: you open the door, and if there's something inside, you choose to put nothing in the chamber the second time you open it; but if there's nothing inside, you choose to add something instead?" I said, and Twilight nodded in the affirmative.

"Exactly," said Twilight. "If we attempted that experiment, I predict there would be something in the chamber. Here's the logic. What ends up in the chamber is determined by tracing the worldline from the point the door is opened for the first time," she said, drawing a parallel line below the dot with its own two dots, "under the assumption that nothing appeared when you first opened the door, which is this parallel universe, below." She labeled the upper line "our universe" and the lower line "identical universe, except test room is empty".

Then she drew three arrows. One arrow traced from the upper-left dot (first experiment, our universe) down to the lower-left-dot (first experiment, universe where nothing was found in the chamber). The other two arrows traced from the lower-right dot (second experiment, the latter universe) up to the upper-right dot (second experiment, our universe), then backwards up to the upper-left dot.

Twilight waited as I took a minute to absorb the idea, and then I gasped in surprise. "Twi, that's brilliant! I can't believe I didn't think of it first!" I squealed. "The prediction function is just the expectation for what would have happened if there were no field at all, and all the quantum effects in the interim... I guess they get 'pre-rolled' to determine what comes out, sort of?"

She nodded. "Essentially, yes. In laypony's terms: what comes out of the first experiment is what we would have put into the second experiment, if nothing at all had come out."

"So the process connects us to a new, past-identical copy of our universe where that event did happen," I deduced. "I'm fairly certain those 'dice' get 'rerolled' again after the door opens, which could lead to inaccurate predictions if we were taking quantum measurements. But for most macroscopic experiments, quantum noise wouldn't have a realistic chance to affect the outcome."

"That was my thought as well. This means we should be able to deterministically predict what will come out of the antimatter chamber if we plan a particular paradox in advance, provided we can be certain we follow through with putting something into the second chamber to annihilate it, even if nothing comes out," said Twilight.

"Hmm. Well, we'd have to use a stooge who didn't understand the experiment, or a robot, or something like that," I said. "Otherwise we wouldn't want to put something into the chamber after nothing came out, which would mean nothing would come out in the first place."

"I've been thinking about that too. Back when I thought we were dealing with time travel of the first form, I was concerned that Starlight could have found a way to use a spell to make the antimatter invisible even when I was downstairs the entire time for that so-called 'six minute' experiment," said Twilight. "It might be possible to cast a spell directly into the magilectric transducers themselves, with a delay trigger. We would have missed the spell with our scans because the transducers are shielded. I don't think this is time travel of the first form, but if it's possible to use the transducers to hold spells it would give us an easy way to control the experiments automatically."

"I don't know if that's possible or not, but even if it isn't, it would be easy enough to use robots to do it," I said.

"I concur. I'm sure you realize what this means," said Twilight.

I did, and the implications were arbitrarily large. "I can hardly believe it, but the conclusions are unavoidable. We could duplicate anything, Twi! Free energy, free matter, all of it, right at our hooftips!" I was grinning from ear to ear, but I felt a chill when I saw Twilight's face remain inert.

"We'd have to hide the technology and maintain strict control over it, but yes. This is the greatest discovery in the history of ponykind," she said, flatly. Her lack of enthusiasm was seriously creepy.

"Wait a moment," I said. "This isn't timelines anymore, this is separate universes entirely we're talking about. That might explain why the device sucks up so much power in order to function. But how does it work logistically?"

"The universes are tied together based on that one difference," she said, pressing her hooftips together demonstrably. "Every branch from a freshly-opened chamber creates a separate universe where that chamber is empty, and that's the universe that determines what appears in the other one."

"But wouldn't we just be tapping into universes that already exist, using the multiple-worlds view of quantum mechanics?" I asked.

Twilight shook her head. "That isn't possible, because nothing about the experiment's framework allows us to connect to other possibilities. It has to be creating some sort of a loop. If this isn't time travel of the first form, then we're literally creating a separate branch of the universe every time we open a door."

I frowned. "Well, that's a problem. If we run paradox experiments to gather resources, we're always connecting one-way. The other universe would need to be otherwise identical to ours, right? So there would be a Twilight and Moondancer there doing the same thing, except it fails, which if your theory were true, would be neigh-impossible."

Twilight opened her mouth, then closed it for a few seconds before opening it again. "You're right. That is odd. Any paradox experiment would have to work asymmetrically, so it would necessarily create a statistically improbable universe. Everything in that universe would be exactly the same, except that an accumulation of bizarre quantum effects would somehow cause their instance of the experiment to fail."

"Well, crap. This sounds like a zero-sum game. I can't see how stealing resources from multiple identical universes is remotely ethical," I said.

"No, it can still work," said Twilight. "The math is weird because we're pairing up an infinite number of possibilities with each other. Even if there are two universes after we open a door, the odds of being in the winning universe aren't simply fifty percent. The odds are nearly certain."

"So... that means all the remaining experiments a 'losing' universe attempts would be neigh-certain to succeed, even though they're also creating two losing universes with each attempt they make," I realized. "Weird. That might actually work, but I'd need to check the math first."

Twilight nodded, then furrowed her brow. "No, wait. Each attempt should create only one universe. If we don't put anything into the doorway the second time it opens, then there's only one universe that gets created: the one we take stuff from."

"It doesn't work that way, Twi. We always have to open the door twice to complete an experiment," I explained. "If we put nothing in, then the air in the chamber goes back in time. Even if we could use a true vacuum, the absence of matter would go back in time. Each experiment must directly create two new universes: the one we take from, and the one we send to. Indirectly, there's no limit on how many spring into being each time we open a door—it could almost be infinite."

"Okay, here's a thought. Assume the air in the chamber goes back in time to a losing universe. Couldn't it go to the same losing universe we've borrowed from?" asked Twilight. "That would create a closed timelike loop between the two universes, and then we'd only be creating one universe with each experiment."

I shook my head. "That's impossible because the odds of the two universes are drastically different, as you just pointed out," I said. "Plus, we could always perform the experiment where we send something different back in return, which would necessarily break the loop. You can get a perfect closed timelike loop to work in a single universe with time travel of the first form, but in that case quantum effects can conspire such that the probability becomes certain on both ends of the loop. With time travel of the third form, you have to make two new connections each time, no exceptions."

"I'm not sure I like the implications of that theory. If we make two universes with each experiment, we'd be creating an exponentially-growing number of universes every time we use the machine," said Twilight. "That means the preponderance of bad universes might be able to catch up to the good ones, and the experiment would once again be unethical."

"There's nothing left to argue about. Let's do the math and see," I said, and Twilight nodded.

We readied our quills, each of us hoping Twilight was wrong.

A Hollow Ring

The math wasn't hard. It didn't take us long to reach consensus.

"It looks like we can only get it to work if we're able to increase the time duration between successive attempts," I said. "Maybe we could send messages back in time to coordinate with the other universes."

Twilight shook her head. "There's no way to guarantee it would be done properly, since the universe we send the message to is already a statistical aberration," she said. "But I'm still optimistic. There's probably a clever way around this, and even if there isn't, there should be ways to benefit from time travel of the third kind without creating any bad universes in the process. We'd just have to abuse it the same way we can abuse time travel of the first kind: plan something beneficial that already meshes with existing data about the past."

"I hate to be negative, but we've already created bad universes," I pointed out. "Consider the world the dead Moondancer came from. She must have come from a world where somepony—probably Starlight Glimmer—opened the door and found nopony in the chamber. If that's the only difference between our worlds, why would I have gone back in time initially?"

"I don't know," said Twilight, rubbing her temple with a hoof. "Just because our theory is deterministic doesn't mean it isn't impossibly chaotic and unpredictable. If your other body hadn't been there on the floor, you probably wouldn't have cast this spell on me. Then we probably wouldn't have come up with this theory yet. All sorts of things would be totally different by now, and it hasn't even been a full day since we broke that particular symmetry."

"Ugh, back to square one," I groaned. "Honestly, though, I'm more concerned about the fact that I was killed at all. There was no blood trail, so I must have died in the lab, which means the killer had access to our lab and almost certainly opened the door I arrived in."

"Then it must be Starlight Glimmer, or else somepony who we allowed access to the lab," said Twilight. "I can't think of a scenario where you or I would have killed a Moondancer, even though there are no doubt a neigh-infinite number of plausible situations in which either of us would do so without hesitation. It seems far more likely that Starlight managed to break in somehow. It would be easy enough for her to do, of course. She could break in at any point in the future, then use our failsafe chamber to go back to last night."

"Oh, that's right! If we hadn't found my body, we wouldn't be eager to shut down the lab," I said. "In the world my dead self came from, Starlight would have had plenty of time to break into the lab. Her travel time would only be limited by how long she could feed and hydrate herself to stay in a chamber without using magic."

"And go to the bathroom," said Twilight.

"Ew," I said.

"This is good news, though. It means we have the upper hoof, and should be able to stop her this time. All we need to do is turn off the power to the lab for a few minutes. That will sever her ability to travel from any point in the future backwards over that particular moment, since the fields need to be running constantly to allow regressive time travel," said Twilight. "We don't need the failsafe of chamber three anymore, and it wouldn't make sense to use it for anything anyway, since it goes to a different universe. We don't want to affect other universes any more than absolutely necessary. One dead Moondancer is more than enough fatalities in any number of universes."

I shrugged. "Well, we have plenty more than that," I said.

"What do you mean?" said Twilight.

"It's like I said, we've created bad universes already. For starters, there's a universe out there where I wasn't able to save your life. You had to go back in time to warn me, and the first time if nothing came out of the chamber, that Twilight would have died, so I would have been the one to travel back in time. There would be several different iterations. At some point I probably died, too, because we wouldn't want to switch from me to you making the trip—that would leave a universe with two Moondancers and no Twilights."

"Is that a certainty?" asked Twilight. She looked very odd with her brow furrowed in thought but the muscles in her muzzle completely relaxed.

Then I noticed something else which brought back a recent memory. Twilight definitely looked healthier than Starlight Glimmer's impression of Twilight had. Both times I'd spoken with Starlight, when she made her wings disappear, I could see the outer edges of her ribcage. She was unusually thin, almost anemic. Maybe she was just a thin mare? But everything else looked exactly like Twilight, so it seemed odd her illusion spell wouldn't have covered that as well. Maybe Starlight had been reflected for a while while maintaining the illusion, and she simply had nothing safe available to eat, so her illusionary body also appeared unhealthy. I had no way of knowing, since I didn't have a clue what normal-parity Starlight looked like.

I wanted to tell Twilight about my two encounters with Starlight Glimmer so she could help me theorize, but I was still afraid to do it while she had the robotic—

"Moondancer?"

I snapped back to attention. "Sorry, got distracted. Yes, multiple dead Twilights and Moondancers are already a certainty. It's not perfectly symmetrical time travel, as we've established. As you go forward through the loops, or backwards for that matter, the more universes you cycle through, the closer the probability of failure approaches one," I pointed out. "That means there are at least two Equestrias with a dead Twilight Sparkle, not to mention one or two with a dead Moondancer."

Twilight froze, and stared off into space. "No. This situation is completely unacceptable. All the ponies in those two Equestrias are likely doomed without access to the Princess of Friendship. And it's probably more than two Equestrias, because of the exponential growth in universe creation. It could be anything short of infinite."

"I don't like it either, but what can we do? I mean, you've already seen me die once from these shenanigans."

"You're less important," said Twilight Sparkle, without a hint of emotion in her robotic voice. It stung painfully, and I struggled to avoid crying, because I knew deep down it was true. "My personal hoofprint is too important to our universe. That was the lesson I learned from my encounter with Starlight Glimmer—my destiny is extremely critical to the future of Equestria. The potential for free energy isn't worth countless doomed Equestrias."

"It is what it is," I said softly, looking away from my emotionless 'friend'. "We know this can't be time travel of the first form, because the antimatter path is invisible. The idea Starlight could have been making the antimatter invisible doesn't make any sense because she would have no motive to manipulate us into thinking we had invented an advanced form of time travel, even if she really wanted to mess with our minds. It's just too ludicrous."

Having barely held back the flood, I slowly turned my head to look at Twilight again. She was lost in thought.

"Moondancer, what did you discover today, if anything?" she finally asked.

"Hmm? Oh, my research," I said, having to refresh my own memory. "Right. I learned that the parity reversal isn't subatomic, in contrast to our prediction. It's actually at the chemical level, which is consistent with something magic can do, but not what the chambers should be capable of. So the source of the effect is still a mystery," I said. Then I paused for a moment as I decided it was time to come clean. "Look, Twilight, something happened just before you showed up, which I probably should—"

Twilight abruptly stood up and walked to the door, without looking back at me. "I need time to postulate," she interrupted, and she left the building before I could even think to react.

I resolved to work on a counterspell for that stupid emotion magic. Twilight was starting to act scary, and I had a bad feeling in the pit of my stomach.

She didn't return in a few hours, so I went to bed.

I woke up so groggy I was certain I was coming to in a hospital bed or gurney for the fourth time in as many days. However, I wasn't lying in a bed. I was lying on a cool metal surface, and it was completely dark. I didn't have my sweater on me, and my muzzle reeked of chloroform.

I opened my eyes wider, still seeing nothing, but I felt fabric against my eyelashes. I realized I was blindfolded. I tried to stretch, but my limbs were bound to my barrel with what felt like rope. I squirmed enough that my rear hooves were able to touch one wall as my muzzle bumped another wall.

Sheer terror filled my barrel. There was only one way the room could be this small. I was in an antimatter chamber, and it was probably on. In all likelihood, I was traveling backwards through time.

"Shit shit shit!" I said, trying to roll over. Something held me in place, however. There was a weight on my back, like two hooves pressing down. I didn't have the leverage to push back against them.

I stopped moving for a moment, and desperately tried to remember what had happened. I couldn't recall anything after falling asleep last night. I must have been abducted in the middle of the night, then transported to the lab. Could Starlight have gotten away with something that bold? Maybe if the guard thought she was Princess Twilight Sparkle.

However, that made even less sense. Starlight was trying to convince me to get away from the lab, so she'd be the last pony I'd expect to knock me out and bring me here. Unless, of course, it was a different Starlight Glimmer. Multiple universes prevented me from taking even the most ridiculous options off of the table.

Theorizing was useless, but I did have the ability to speak. "Let me go, please!" I cried out. Immediately, I felt like a coward, but my mouth wasn't connected to my conscious mind. I was operating on pure instinct, and instinct said 'beg'.

I heard a sigh from above me. It was followed by a strange vibrating noise like a soft jackhammer, then a distinct 'click' sound of the door unlocking.

Then my senses started going crazy. I was still alive and conscious, but extremely disoriented. I couldn't tell if I were breathing out, or in, or both at the same time. The pressure on my back disappeared, but suddenly the air pressure everywhere around me began to swell. I tried to roll over, but squirming felt like I was immersed in gelatin. Something pressed against me, like another body, then somehow it pressed into me, everywhere at once.

Then the same thing happened in reverse: I separated from a Moondancer-shaped lump as I rolled over and over. It felt vaguely like I had been kicked. There was a lurching sensation, and warm wind rushing over me as the pressure dropped. It felt like I was rolling in two directions at once, and if I hadn't known better I would have sworn I'd ended up right back inside the chamber where this had started.

I heard a door shut, and somepony ripped off the blindfold. Now I was staring up at my good friend Twilight. It was clear from her lack of disorientation that she hadn't been the one in the chamber with me. I felt a great sense of relief, but adrenaline still surged through my veins.

"Moondancer, are you alright?" she asked as she removed my bindings. I stood up on three shaky legs and one rolling cast, and kicked the cursed rope away from me. Looking around, I noticed the anteroom looked normal, with a few minor exceptions. There was no blood on the floor, even though the club was lying here, so I assumed Twilight had cleaned it up. The only true oddity was that the bathroom door was now located on the opposite side of the room.

"Thank Celestia," I said, breathing a tremendous sigh of relief. "I was petrified that Starlight Glimmer was going to be on the other side of the door! Wait, this is the past. You haven't formulated the theory on how the chambers work yet."

Twilight shook her head. "No, I have. I traveled into the past in order to meet you here after you got kicked out of the chamber," she said. I stared at her and began to feel concerned. Twilight looked gaunt, as though she hadn't eaten in several days. I realized that she wasn't flipped to her false (mirror) image: the stripe was on the correct side of her mane. But that was from my point of view, so it was clear we were both parity-reversed, which matched her story.

Then I had a terrible thought. I wondered, if Twilight tied her forelock up like mine, whether or not I'd notice if the stripe were on the wrong side. I wasn't sure.

"How long have you been reversed?" I asked. "Twilight, you need to drop that bucking spell and tell me what's going on."

Twilight's face remained vacant of emotion, but a tear trickled from the inside corner of one eye down her cheek. "This is very hard for me, Moondancer."

"Wait, the spell is down? But you still look and sound like a zombie!" I said, grabbing her by the shoulders.

"The spell isn't down. It's just imperfect, and the magic is being pushed to its limits right now," she said calmly. "Moondancer, you once told me if I had to choose between you and Equestria—"

"You should choose Equestria, and yes, that still applies," I said. I put my hooves back on the floor. There was a slight rattling sound. Both of my forehooves were jittering in place against the metal.

Then Twilight stepped forward and kissed me right on the mouth. It was soft, but hollow, without any feeling. As she leaned back, my jaw hung open.

"My second kiss," I said, stunned. "But you'll remember this one, at least, right?"

Twilight nodded. "Of course. But I now suspect this one was my first, in both senses of the word," she revealed. "I'm so sorry, Moondancer."

I noticed Twilight's horn glowing, and I didn't see the club on the grou

The Miracle

There's a ringing in my ears, when I shouldn't have ears. On a primal level, I know I should be dead. Yet, somehow I am not.

"Welcome back," calls a soft, if unfamiliar voice.

My vision takes a little longer to return, but that's no surprise: vision requires more physical energy for the brain to process than audition does. So if you're, oh, let's just say, being clubbed to death by your best friend, you're more likely to stop seeing things before you stop hearing them. Of course, this doesn't apply in my case, because a single blow was all it took. But the same fact holds true in reverse.

I struggle to move. I find that I'm in yet another hospital bed, and my foreleg is in traction again. This makes for a total of five knockouts in half a week, which, though very impressive, is not something I've ever wanted the bragging rights to.

My bandaged forehead throbs painfully, but it's my heart that hurts the most. I squint as my vision slowly returns, and I see a distinctive golden aura everywhere at once as my glasses are levitated onto my face by somepony. My sight is still bleary, but it's obvious that the pony beside me is none other than Princess Celestia.

As a talented mage, I've met Princess Celestia several times before. It was always in a formal setting, and she always exuded this kind of otherworldly peace. She's smiling at me now, very sweetly, her pastel-hued magical mantle billowing through her mane and tail.

All the other times I'd met her, I was star-struck. But not this time. Her flowing grandeur and gentle demeanor are irritating, and they feel pompous. This pony taught Twilight to be a princess, Twilight chose to end my life, and now here she sits with a soft smile on her pretty little face.

I want somepony to blame, and I won't allow it to be Twilight. So it's either Celestia or me, and I can't handle me at the moment.

"Meperidine," I demand, and she hoofs me the squeezer, which I gratefully tap.

"You've been in hospitals a lot recently, from what I hear," says Celestia. Her voice is soft and soothing, which I want to find annoying, but I can't. "You deserve the relief, but please take care with your doses. It is surprisingly easy to become addicted."

"Too late," I say. "That squeeze wasn't for physical pain."

"I understand," says Celestia, with a small sigh. "Fortunately, there are other ways to alleviate psychological trauma, at least in the long term."

I snort. "I know a spell to do it, but I'd sooner die than cast it again." I say that actually hoping I get in trouble for knowing the proscribed spell. I feel small and dead inside, despite the drug euphoria now filling my core. I want to suffer. I'm not entirely sure I understand why.

Celestia's head gently bobs in response. "I want you to live, Moondancer. Still, I'm glad to hear you say that. I don't know how you learned Dividere Mentem. I don't believe in censoring inquiry without just cause, so that particular spell is illegal for some very important reasons. I'm sure you understand this, now. Later, preferably with your consent, I intend to wipe part of the formula from your memory. I have already done so for Twilight and myself."

"Yourself?" I ask, shocked. "You did something to keep yourself from casting a spell?"

I can hardly believe what I'm hearing, but I'm starting to realize that maybe, just maybe, underneath all that polished charm Princess Celestia might secretly be a real pony.

Maybe.

"Oh, yes," she says, and a wistful look crosses her muzzle. "I removed it from my mind a very, very long time ago, and at the time I also put up other barriers to ensure I would not relearn it. I probably should have destroyed it, but it's difficult to bring myself to ruin any brand of knowledge. Regardless, while it is true that our decisions are best ruled by adherence to facts and logic, it turns out that emotions are, in fact, a very important component of ethical decision-making."

"You also covered up time travel of the third form, didn't you?" I accuse. "And actually, I guess it turns out Twi and I don't know what that is after all. I suppose you'll tell me that information is forbidden for good reasons too?"

Celestia waves her head gently from side to side. "I'm afraid I lied to Twilight about that, because I feared the two of you were working on something very dangerous. I figured it might spook her into slowing down. In truth, there's no such thing as a third form of time travel, to the best of my knowledge," she says. "That idea was a distraction I slipped into textbooks written long ago to make it appear that there was a more powerful kind of time travel. It's the second form that is dangerous. Fortunately, that magic is very difficult to master because it requires communing with the Tree of Harmony. But the point of the ruse was my hope that ponies like Starlight Glimmer might give up on learning the second form, and try to pursue a dead-end spell instead."

"Clever," I say. "But disturbingly sneaky."

"I admit it was a questionable plan. I'll probably never know how well it actually worked, since those cases would be the ones we're spared from," she says. "However, I fear I must return to the matter at hoof: Twilight's actions."

"Her... oh, right. Eh. I don't know anymore," I say. "I can't really fault Twilight for what she did. Maybe if she hadn't had that emotion spell up, but even then I can't blame her decision."

It almost feels like I have the spell up now, I realize. I'm sure waterworks are on the horizon, but at the moment, everything just feels empty and numb.

"Twilight Sparkle speaks very highly of your intellect. I suspect you might have figured things out already?" says Celestia, intoning it as a question.

I nod my aching head. "It's pretty straightforward. Twilight and I discovered that if the chambers worked the way they seemed to work, we would have already produced a slew of universes where Equestria was doomed to some disastrous outcome," I explain. "Then she realized she had the opportunity to go back in time and rig it so that the experiments were actually time travel of the first form all along. So she kidnapped me and took me back through the failsafe chamber. When I woke up, she kicked me out of the chamber but stayed inside of it herself. Once she ended up at the start of this mess, she destroyed test chamber two, then cast magic into the chambers to make it appear like symmetry had been broken when it actually hadn't."

"You are correct. In doing so, Twilight saved countless otherwise-identical Equestrias by preventing their existence in the first place, which is a probabilistically preferable outcome. So all of the events took place here, in this Equestria," says Celestia.

"Yeah, that was the payoff. Then after several days of shenanigans, she met me when I came out of the chamber and tried to kill me. Then, thinking she'd succeeded, she dropped the emotion spell, felt guilty, and tried two or three times to undo her own plan by changing events—namely, my actions—without directly confronting herself. It makes perfect sense, in retrospect. Obviously, her attempts were in vain. I rebuffed her each time, because I didn't understand who she really was or what she was trying to do," I say. "But I'm surprised that when she still had that cursed spell up she didn't plan more effectively to keep me dead."

"She tried to. In order to ensure her success, Twilight also destroyed 'chamber zero' before she traveled with you through the failsafe chamber, which I believe Twilight mentioned was chamber three," adds Celestia. "Since she had already destroyed chamber two, and your body traveled through chamber one after she attacked you, there would be no way to return to the past again to save your life."

"But then... how in Equestria am I still alive?" I ask, dumbfounded. For a brief moment, the mystery is almost enough to numb the emotional pain.

Celestia smiles, but the smile quickly fades. "You know, I've known Twilight Sparkle for almost all of her life," she says, staring momentarily out the side window. "And I've personally lived through centuries, as you certainly know. In all that time, I don't believe I've ever seen a pony more distraught than Twilight was when she came to me yesterday, begging for her punishment. She needed to be restrained and sedated. Twice, actually. It was most fortunate I recognized the stripe was on the wrong side of her mane, although I did have another clue. If Twilight is feeling up to it, she can tell you about that one herself."

I sigh. "Well, I guess at least she feels bad about what needed to be done. But I don't know if she should. She made the logical decision," I say. I try to make it sound sarcastic, but it really isn't. I mean it, and it hurts.

"That's exactly what I told her," says Celestia, and I feel a sudden knot in my stomach.

"Wow. You really are kind of a bitch," I say, my already-sparse filter damaged by the emotional pain as much as the drugs. I immediately regret it, but then almost as immediately, I take back the regret.

Momentarily, Celestia looks shocked, and maybe even angry. But then that soft smile returns to her mouth, and she lets out a short laugh. "Yes, I... I suppose I've earned that one," she admits.

I don't really know what to say, so I just look away from the princess as tears begin to stream down my cheeks.

"However," she continues, "the logical choice is not always the same thing as the correct choice."

I wipe my eyes with a hoof and turn back to face her. "What? No, that's false. Killing me was the right choice. I'm worthless compared to an innumerable amount of Equestrias! Tartarus, I'm even worthless just compared to Twilight," I say, my voice catching in my throat.

"I most emphatically disagree, Moondancer," says Celestia, suddenly wearing a stern frown. "In Twilight's partitioned emotional state, she forgot the true lesson she learned from her second encounter with Starlight Glimmer. Yes, it may be true that she and her five friends were destined to save our world, and certain critical points in history are more important than others. But everything we do matters, my little pony. Every friendship is essential to the future of our world, and that is not an exaggeration, as I hope you will someday learn. In particular, your friendship with Twilight may—and very likely will—be equally important to the fate of Equestria. At least, it will, should you one day choose to continue it, after what she has done to you."

Celestia telekinetically hoofs me a box of tissues, and I start to dry my eyes. "No... I won't believe it. There's no way that I'm as important as Twilight is."

"But you are," says Celestia in contradiction, smiling gently down at me. "Just look at the mess a single avenue of your research made in the space of a week, and tell me that your actions don't have an impact on the future of Equestria."

I smile, despite myself. "Okay," is all I can say for the moment, and she patiently waits for me to dry my eyes again. My glasses keep getting in the way because I can't hold them up with magic—it hurts my forehead too much to try. "So, how am I alive, again? The suspense is murder. Um, pun not intentional."

"Ah, yes. Well, after I managed to get all of the information out of Twilight, I asked her to stop and think very carefully if there were any remaining options that could possibly save you," she says. "As it turns out, after taking your failsafe chamber back to the beginning, she ended up correcting for every detail except one."

"Which one was that?" I ask, still very curious even as I lie here drying my eyes with tissues.

"She neglected to dispose of your body after you sent it back in time. It was the one loose end she forgot to tie, probably because even in her broken emotional state she wouldn't allow the thought to cross her mind," says Celestia. "Once we realized a piece was missing, she unraveled the rest in short order, then set upon a second quest in the hope it could save your life. That hope was far from certain, but she clung heavily to it."

The gears in my head were turning more slowly than usual, but they still turned. "Twilight must have gone back in time again to cast something that would make it seem like I was dead... I guess somewhere between the time she knocked me on the head, and the time we discovered me. But in order to rescue my body, she would have needed to go back even further," I say. "And that's the problem: she had already used the failsafe, and destroyed the only chambers that could have taken her back that far. The Twilight with the emotion spell was inside chamber three the whole time all of this was going on, chamber one had my 'dead' body in it, and chambers zero and two were destroyed. There shouldn't have been any way for her to travel back a second time."

"Are you certain?" says Celestia, raising a brow inquisitively. Then she sits quietly as I try to decrypt the final piece of the mystery.

It finally hits me. "Oh my Stars. After Twilight inserted the IV bag into chamber zero, we never performed experiments in chambers zero and one at the same time, so... she could have alternated chambers and used them both as a combined failsafe—that's it!" I say, with a genuine laugh. "She took chamber one back to a time before chamber zero was destroyed, then waited ninety minutes and took chamber zero back the rest of the way! Twilight, you clever bucking mare," I say. "So she was in chamber zero when chamber one was being used, and chamber one when chamber zero was unavailable. As well as being Robo-Twi in chamber three the entire time, of course. That's awesome."

"I thought you'd appreciate that," says Celestia. "She went through an incredible amount of trouble to save you, Moondancer, and it has taken a substantial toll on her emotions. For lack of a better way to say it, Twilight Sparkle is a wreck right now. However, none of this excuses her trying to take your life."

I pause a moment. "Wait, she's not in trouble, is she?" I ask. "I used a forbidden spell on her! I'm at least as guilty—"

"Shh," soothes Celestia, gently tapping my muzzle with a shining golden shoe. "It's all right. While Twilight is not absolved from the responsibility of her actions, she has definitely suffered enough, and in the end, you did survive. Luna and I shall not attempt to punish her further. Besides, I also share some of the responsibility for Twilight's actions. I've been pushing her very hard lately out of concern for whether or not she is ready for these exact sorts of difficult situations. Instead, I should have been providing her the emotional support she needed to gain confidence in her own abilities."

I let out a deep sigh. "I'm really glad to hear you say that. Twi's been meaning to talk to you about the pressure, and I was ready to chew your ear off about it if she didn't," I say. "But, um... what would have happened to Twilight if I hadn't survived?"

Celestia takes in a deep breath. "I don't really know, and I'm glad I don't have to consider that case. Powerful mages like you and I, as well as our friends, tend to get into situations where standard moral imperatives don't always apply in a clean-cut manner. And there's certainly no legal precedent by which one could evaluate the relative importance of saving alternate universes. But the rule of law still applies, as much as it can," she says.

I just nod and listen to her as I blow my nose.

"Last year, Twilight annihilated several dozen semi-sapient clones of Pinkie Pie without even batting an eye," she adds, with a small sigh. "I agree it was the best solution from a utilitarian perspective, but morally speaking, where can one even begin to weigh these sorts of choices? I don't know the answer, but I never did have the heart to tell her one of them escaped her notice."

"Being a mage and having friends at the same time is more complicated than I'd originally hypothesized," I say.

Celestia gently nods in agreement. "All that aside, I want you to understand that you aren't obligated to forgive her, Moondancer, even though you are in truth the only pony who can. Not today, certainly, and not ever, should you choose."

"Well, my schedule's free at the moment, so... I guess today works best for me," I say with a sheepish smile. I barely notice a tension leaving Princess Celestia's muzzle, a subtlety I wouldn't have been able to pick up on before spending so much time with Twi. I can tell she's relieved, and I can understand why. I've already forgiven Twilight, but I'm sure she's hurting much more than I am.

Celestia stands and walks to the door, opening it a crack, and whispers something as she exits. I can hear somepony sniffling, and then, very slowly, Twilight Sparkle creeps into the room. Her head is bowed, her ears droop back, and she's crying drops onto the hospital floor.

As Twilight tilts her head up and looks at me, I'm actually frightened by the responsibility. In her eyes, I can see her waiting for a death blow, as though I have the power to kill her where she stands with a single word. And the scary thing? I probably do. But I also know I wouldn't let that happen in a trillion iterations.

"Muh-muh, M-moon, I, I..." she stutters and chokes.

I sigh. "Get over here you big dork," I say, with enough of a smile that she knows, and she runs to me.

I can't reach out to her because the forehoof on her side is in traction, but after she's close enough to bury her face in my lap and sob maniacally, I can at least pet her mane with the good one.

"I'M S-SO SORRY," she moans, though it's hard to hear with her face buried in the blanket on my belly.

"It's okay," I say, because it is. "I forgive you."

"I d-don't d-deserve it," she says. My horn isn't helping at the moment, so I share the tissue box with her by hoof.

"No, I think you do," I say. "You can't get rid of me that easy. I'm in this for the long haul."

"Why?" she asks, trying to mop the tears from her cheeks.

I fear saying the wrong thing, but I decide to follow Applejack's wisdom. "Because I love you," I tell her. "I can't stand to see you suffer like this. Also, it helps that that teacher of yours always knows just the right thing to say. Um, I definitely don't have that talent, so I really hope I'm not screwing this up right now."

She hugs me awkwardly. "You're not," she says. "And I was so wrong, I just—you're not less important to Equestria than I am, Moonie. You're just as important as I am, and to me, you're more important."

I wipe away a tear or two of my own. "Oddly enough, I think I'm starting to gravitate toward that theory myself," I admit.

"I, um, I might need to clean myself up for a while, and m-maybe cry some more. Then I can come back and we can talk," she says. "Oh Stars, I'm so happy you're okay."

I shrug a little, or at least do the best approximation I can with one foreleg unavailable. "I am too. To be honest, I'm still pretty shaken up, though. I might need some therapy," I say, in all seriousness.

"I'm sure I will," gasps Twilight between sobs.

"Well, maybe we can go together?" I offer, gently stroking her forelock. "I don't quite understand about the 'love' thing yet, but I think we can figure that out together too."

Twilight just smiles up at me and wipes her eyes. Celestia was right, she looks absolutely terrible. Yet somehow, that smile on her face is easily the most beautiful sight I've ever witnessed.

"This is off-topic, but did you find out who backed me?" I ask.

"Oh! Princess Celestia did," she says. "She funneled the bits through Manehattan to hide her tracks. We needed an accomplice in Manehattan we could trust, so I connected her with Rarity's close friend and associate Coco Pommel."

"But that was long before I first turned on the machine," I say. "How did you go back even further?"

"I didn't have to. I had Rarity use a modified version of Star Swirl's spell which allowed her go back in time a few weeks and deliver a note to Princess Celestia where I told her I needed her to loan Coco Pommel an extravagant amount of Equestrian bonds for research purposes, which I promised to pay back," says Twilight. "Granted, that last part was a lie, but Celestia has the bits to spare, and it also gave her a clue that I was involved in time-based shenanigans."

"Hmm, creative. Wait—isn't Celestia sore about wasting millions of bits on my doomed project?" I ask.

"Not at all. She doesn't care about money. She cares about ponies," says Twilight, in a simple, matter-of-fact voice. Then she nods and hands me back the tissue box. "I'll be back in a little while, but in the meantime there's somepony else who needs to talk to you. Thank you so much, Moonie."

"No problem, Twi. And hay, if our friendship can survive attempted murder, I think we're pretty much doomed to be friends for life," I say. By some miracle, we both manage to giggle through the tears. Twilight walks out of the room, and I breathe a huge sigh of relief as my guard drops. Social interaction can burn through a lot of calories, especially when you really care about the outcome.

I assume my sister is next, or maybe Lemon Hearts or one of my other friends, even though I'm not really in the mood for more company. I'm taken entirely by surprise when Princess Luna enters the room.

"Three princesses in a row?" I ask. "That's got to be a record."

"You would seem to be a very important mare," says Princess Luna, with a wry smirk. "And to think, I was interested in befriending you prior to all of this recent madness. I must be an excellent judge of character; it would no doubt behoove me to become well-acquainted with a mare of your stature, Moondancer. Perhaps you are even a pony upon whose withers the fate of Equestria may someday burden."

"I don't know about that," I say. "I don't want to be a hero, especially not after all this."

"Alas. I regret to inform you that your response is precisely what a hero would say," she replies. "We rarely have much freedom in that, I fear."

I roll my eyes. "Gee, what chance does that give me?"

Luna smiles. Ironically enough, I find her personality much warmer than her sister, but I can finally sense the sisterhood between them. "And now I have you present as a captive audience, so you can no longer escape my introductions."

I chuckle. "Heh, thanks."

"Allow me to 'cut to the chase scene', as they say. You are a remarkably powerful mage, Moondancer, despite your young age," she says. "In our brief meeting from before, I believe you had informed me that you are new to the magic of friendship?"

I sniff dismissively at that. "Yes on being clueless with friendship, but I don't know about the 'powerful mage' bit. I enjoy magic, but I'm no Princess Twilight Sparkle."

Luna huffs. "Twilight Sparkle is still learning, just as all ponies do. You know, she has yet to fully understand that she has grown beyond the framework that my sister has laid for her," says Luna. "She continues to compare herself to Princess Celestia in an unrealistic fashion, as though her constant approval is still necessary. After all her lessons in friendship, Twilight still lacks confidence in who she is. Her mentorship of Starlight Glimmer will be a worthy challenge for her."

"She'll get there," I say. I don't really know, though. "She's going to mentor Starlight? Yeah, I guess that makes sense."

"Moondancer. My point is that Twilight cares for you because you are your own pony. Your self-worth should not be yoked to her shadow, as hers remains tied to that of my sister."

"I know," I say. "This... thing we just went through finally opened my eyes to that. But like you said, I'm pretty new to friendship."

"Ah, yes! On that remark, I am reminded of the primary purpose of my visit. I shall put it in a straightforward manner. My sister gets to have a personal protege. Now, even Twilight Sparkle has a protege in Starlight Glimmer," she says. "I am, quite frankly, gripped by the bonds of avarice, and I intend to remedy this injustice forthwith."

"You mean..." I say, afraid to draw the conclusion prematurely.

"Moondancer, I would have you as my personal student," says Luna.

"I... I don't know what to say."

"Oh. You should say 'yes'," Luna informs me.

"Um, then, yes!" I say. "And you know, I could probably use this as an opportunity teach you a thing or two about quantum mechanics, if you like."

Luna grins. "Excellent! You know, every good mentoring relationship requires learning on both sides. This is something my sister is presently rediscovering," says Luna. "I believe that she and Twilight Sparkle will both grow a great deal from what has happened this day."

"I certainly hope so," I say, sniffling as I try not to cry happy tears. Today's been maudlin enough already.

"Now for the time being, I think it would be best for you to remain in Canterlot, but your friendship assignments will frequently require travel to Ponyville," she says. "The friendship that you share with Twilight Sparkle is of particular academic interest, and shall require further study, in depth."

Then Luna winks at me, and I blush like a firestorm.

"I think I can manage that," I say, and I dab my eyes again.

With that, Luna bids me goodbye and leaves me to my thoughts.

I won't allow myself to be unrealistic about my future. I know the path will be hard at times. Hopefully it'll never, ever be this hard again, but on occasion there will be fights, and misunderstandings, and mending of fences anew. Wherever my friendship with Twilight ends up taking me, I'll embrace it: the good and the bad together. I think she's—no; I think we are worth it.

After all, friendship is about sacrifice—on both sides of the equation.

I think I can live with that.