That's The Night The Lights Went Out In Canterlot

"…And how art thou able to fly?" Luna asked just before Reggie woke.

Reggie continued to lie in his bed for several minutes while he contemplated this latest dreamwalking session with Luna, Rainbow Dash and her friends. Luna's question didn't bother him so much as the feeling that something about the dreamscape was wrong, something that was quite out of place.

No doubt, they were all waiting for him to reenter his slumber so that they could resume. But the oddness was keeping him from relaxing. Rubbing his temples, he tried to force himself to relax.

Force myself? he thought, snorting. Like that ever works.

Frustrated, he flung off the covers and walked over to the dresser so that he could make himself presentable to the princess.

"Hey, Ralf. Sam," he greeted when he stepped out from the suite. He felt something of a triumph in that he didn't need to hold onto one of their withers to help guide him down the passageway toward the route that would eventually take him to the throne room.

He turned off the passageway and into the correct intersecting corridor that would take him toward the heart of the castle. There were a few more turns like that which finally led to the castle's main entrance. He knew of the side passageway he could have taken earlier, but he knew that not being one of the castle staff, he was aware of how inappropriate it was for him to have used such.

Still, it filled him was a touch of pride that he not only didn't need to have Luna's guards guide him, but that he had been able to take the lead the entire time.

And at their approach, the unicorns standing guard on either side of the doors to the throne room pulled open their respective panels.

"I apologize, Princess Luna," Reggie began, rubbing the back of his head. "For some reason, I'm unable to get back to sleep."

"'Tis perfectly alright, Reggie," Luna said from her throne. She watched as Reggie finally stopped his approach just shy of the steps leading up to her and Celestia's thrones. "'Tis also remarkable about how thy navigation hast improved so. Thee arn't even using the cane that Laughter hath made for thee."

"What?" Reggie exclaimed, suddenly turning about, trying to picture the throne room in his mind.

Was it just muscle memory that led me here? he wondered.

In his mind, he could sense the dimension of the chamber. Over a dozen-and-a-half paces wide, well over a hundred long. Two unicorn guards standing on the inside of the main entrance, just as the pair was on the other side who had opened the doors for him and the two batponies accompanying him. Two batponies, one on either side of the bottom the stairs. And Luna, who was about halfway down the steps approaching him.

Reggie's head snapped about to look at one of the batponies standing at the stairs.

"Ralf? Sam? H-how do I know there are a couple of batponies standing here?"

"There is always a pair of guards standing there," Ralf replied, evidently confused.

"But how do I know they're not unicorns?" Reggie challenged. The guard in question suddenly looked at Reggie in turn. "Or earth ponies?"

"Reggie?" Luna got out before the growing headache took him down.

Reggie's last memory was the unknown guard and Ralf were rushing to catch him.

"I'm sorry," Doctor Splint said, stepping out from Reggie's bedroom to speak with Celestia and Luna who were standing in the suite's guest area. "It appears that his occipital lobe has completely atrophied. I'm afraid he will never regain his sight."

"How is that possible?" Luna demanded. "His awareness of his surroundings in the throne room was uncanny. 'Twas as if he were able to see the guards standing there!"

"He certainly wasn't doing it with his eyes," Splint countered. "You said it yourself, he was wearing those goggles Pinkie Pie had made him. Even had his vision been restored, he'd see nothing through that!" He held up a couple of films with his magic to look at the images from the ambient lighting.

"Can we go in to speak with him?" Celestia asked.

"He was complaining about severe headaches," Splint replied. "Not surprising, seeing these scans. I've given him some sedatives to keep him under."

"What's happening with him?" Luna asked.

"I'm not rightly sure, myself," Splint told her, holding the scans out to her. "As you can see from this scan, taken when he first arrived, his occipital lobe had extensive bruising. But it was light enough there was hope his vision would recover. However, this second scan not only shows the areas of bruising have atrophied, but that almost his entire occipital lobe has shrunk to almost nothing. Not only that, but these two temporal lobes seem to have expanded into the space vacated. It's no wonder he was having headaches."

"Does he know?" Celestia asked.

"Not yet," Splint said, shaking his head. "His pain was so bad that he was out as soon as I provided him with the painkillers. This second scan was taken while he was unconscious."

The world was a box. A large green box. The walls, ceiling, and floor all glowed bright green. There were exits from the box. On one side, there was an open doorway leading to a smaller room, with all the surfaces also glowing bright green. And somehow, he was able to "see" almost the entirety of that other room. Even around the corners.

There was another doorway at the far end of the box. But it was closed. The closed door also glowed green, just not quite as bright. There was finally a large balcony-style window that glowed brightly green.

Inside the box, there was a bed. This too was green, but a very dark green. There were other furnishings in the box. A dresser. A dining table with a chair. A couple of end tables on either side of the bed. A reading sofa along with and end table on either side as well as a long coffee table in front of it by the window. Most of the furnishings were the same color green as the door. The sitting area of the sofa, however, looked as dark as the bed. As did the dark green carpet covering much of the floor.

And on the bed, there were two figures.

One was human.

The other was a pony.

Reggie recognized himself as the human.

The pony was harder to figure out. She, like him, was green.

Her features looked somewhat familiar, but with the colors, he was having a hard time placing her. None of Rainbow Dash's friends—or at least the ones to whom he'd been introduced—were green.

As his awareness continued to expand, he noticed something odd about the pony. There was a pulsing organ in the center of her chest. Staring at it, he saw a rhythmic pulsing of green-yellow/green-blue going at a steady rate. But then, as he looked back at the pony's face, trying to recognize her, he saw there was a similar pulsing object in his own chest!

Weird! he numbly thought.

He put that thought aside for the moment.

Her messily cut mane looked familiar, but he still couldn't place it.

She had wings, so she was a pegasus.

Her tail was also sported an unkempt cut to it, like it had been hacked by a knife. Again, a familiar shape, but the coloration was too confusing.

Her rump was just a blank green, same as her fur.

So why was her head lying on top of my chest? he wondered.

Why do her features look so worried? And why is she crying?

He reached his left hand up to gently stroke her mane.

"Hey," he croaked. "You a friend of Rainbow?"

Her eyes snapped open and God that was so freaky! Bright green eyes and no irises! he thought.

"Hey! You're awake!" Rainbow Dash's voice cried out as her head yanked off his chest. There was a momentary painful pull, like tape getting yanked, and Reggie saw that his medallion had been lying between her head and his chest for God knows how many hours. It was glowing bright green.

"Heh! You should see your face!" Reggie snorted at the sight. "You've got my medallion permanently imprinted on your cheek! Ow! And I think in my chest, too!" he grumbled, rubbing at the sore spot.

Then it finally dawned on him.

"Holy shit! I CAN SEE!"

"N-n-no, Reggie," Rainbow said, looking wretched. "No, you can't."

"What are you talking about?" he asked. "I'm looking right at you!"

"You're wearing your goggles, Reggie."

"So you're saying there's no way to get my vision back?" Reggie asked after having his condition explained to him.

"Not with these changes to your brain, no," Doctor Splint told him.

"Then how can I see you? All of you?" Reggie demanded, pointing at the five ponies in the room with him using the set of goggles in his right hand.

"I don't know," Splint said, shrugging his arms. "But it's not with your eyes."

"Do we know what caused these changes, Doctor?" Celestia asked.

"I'm afraid I don't. I've never heard of anything like this before," he replied. "And without an understanding of how his species reacts to magic, I have no baseline by which to even guess. But if I had to guess, it's either something that happened gradually over a period of weeks at the least or instantaneously, as a result of getting hit with a spell."

"We hath noticed that his dreamscape hath been changing o'er the past few weeks," Luna intoned. "Normal colors that he shouldst experience as have become muted of late…."

"'Weeks', you say?" Twilight nervously asked.

"Four or five, at a minimum," Splint confirmed. "Anything less would likely have killed him. Unless it was a spell, specifically designed to make these changes. And the pony who cast it would have to be exceedingly skilled not to have turned him into a turnip, figuratively speaking."

"Thee knowest something of this, Twilight Sparkle?" Luna demanded.

"Zecora's potion?" Twilight ventured. "That was about seven weeks ago."

"Oh, God! Don't remind me!" Reggie shouted, almost exhibiting a gag reflex. "I only recently got the memory of that taste out of my mind!" Then he blinked.

"Wait…" he muttered. "You're not saying…?"

"It's possible the potion didn't have exactly the desired effect," Twilight began, but trailed off as she dreaded his reaction.

"Huh! So, instead of my sight back, I got—what? Some sort of perception of my surroundings?" Reggie asked. "I see everything about me as various tints and shades of green. Hard objects are bright green. Furred and feathered ponies are quite a bit darker. Oh, and the carpets throughout the castle are a dark green, too. I remember it used to be red, at least according to my dreams. It's like looking at the world through one of those ancient CRT monitors that only had a black and green display. Except…."

"Except what?" Twilight asked after the long pause.

"I'm seeing … something … I'm guessing … is your heart … in everybody's chest," he said. "They're pulsing, with a yellow-green to blue-green color. As are Rainbow Dash's wings," he added, looking at the hovering pegasus in the room.

"Really!?" Twilight exclaimed, her ears perking up. Then she began scribbling something on her parchment.

"Yeah…" Reggie nervously said. "And … your … quill, now. It's actually flickering from full yellow to blue!" There was a pause, and then Twilight resumed her scribbling. "Now, orange to indigo!" But that didn't slow her down. And her heart was also pulsing between full yellow to blue.

The others held their peace until she was done with whatever calculations she had been doing.

"Ohmygoshohmygoshohmygoshyouknowwhatthismeans!?" she exclaimed when she was done.

"That yer talkin' like Pinkie Pie?" Rainbow Dash asked.

"No!" the green—well, one of the green, Reggie reminded himself—alicorns said, glaring at the pegasus.

"It means he's seeing the world through sound!" Twilight yelled.

"Ow!" Reggie exclaimed, wincing in pain.

"Oh, sorry!" Twilight sheepishly whispered.

"So, I'm like that comic book character, Dare Devil?" Reggie asked. "Or like how everyone thinks the Batman operates?"

"I've—no idea who those are," she admitted.

"Oh. Right. Never mind," Reggie said.

"Wait! How far can you see with your sonar sense?" Rainbow Dash suddenly asked.

"I've no idea," Reggie replied. "I've not stuck my head outside the castle for some time. What do you have in mind?"

"Well, now that you can finally see," she began, "even if it's not in awesome technicolor, you can watch me as I pull off some of my signature moves!"

Reggie thought about that for a few moments.

"Heh! Sure! Sounds fun!" he said, grinning.

"Well, of course, we're going to have to confirm just how far he can see, first," Twilight said.

"So how far am I supposed ta fly out, again?" Rainbow Dash asked.

"Until he can't see you anymore," Twilight repeated to her. "Then I'll signal you with a flare. When you see it, mark how far out you are. Then head on back so we can estimate his range."

"Seems simple enough," Rainbow grumbled.

"Don't worry, Rainbow," Twilight told her. "You'll be able to show off your stuff soon enough."

"I could show him right now!" she protested.

"But if you fly outside his range, he won't be able to watch it," the small alicorn countered.

"That makes no sense."

"Trust me on this, Rainbow!"

"Sheesh! Ya have ta make everything an exercise in egg-headedness," Rainbow Dash grumbled as she flew off.

"That's not even a word!" Twilight growled.

Reggie just silently grinned at the banter between them. He suspected Rainbow was just trying to push her buttons to get a rise out of her.

He watched as Rainbow flew off, her green form turning yellow, then orange as she departed and picked up speed.

"How odd the world might look like if light traveled at the same speed as sound," Reggie said.

"What's that?" Twilight asked.

"Oh, just paraphrasing something that Einstein once said," Reggie replied, glancing down at her. The baffled look on her face needed no translation.

"Albert Einstein," Reggie explained, looking back up to keep track of Rainbow Dash. "He was a theoretical physicist who discovered General Relativity and how no matter could travel faster than light. Or even reach light speed. Part of his proof was calculating how the world would look if light traveled at some other, arbitrary velocity, say … thirty miles an hour, I think it was."

"What good would that do?" Twilight demanded.

"He explained how a person, riding a bike, as they approached the speed limit, how his mass would increase, his length would shrink, and his vision would be focused into a narrow cone. Objects in front of him would become highly blue-shifted, and that at the edges of the cone, he would actually be able to see objects that were behind him and they would be greatly redshifted. And no matter how hard he tried, he'd never be able to reach thirty miles an hour."

"Really?" the small alicorn asked, evidently stunned at the concept. "But why ever did he chose that speed?"

"It was just a thought experiment he came up with," Reggie replied. "I think he did it to help put the idea of actual light speed travel into perspective, so that others could try to understand."

"Huh! I never would've thought of trying to imagine something like that!" Twilight said. "I know that in normal space-time, nothing can reach light speed. And those effects would be experienced by anypony trying to do so. But to even think of trying to explain it by changing the speed of light…" she was saying as she scribbled something down on her parchment.

"And I think I'm losing sight of her," Reggie said, interrupting.

"Oh? Oh! Right!" she exclaimed, as she fired off a flare with her horn.

"But to figure out the dynamics of that thought experiment, I'm going to have to…"

"Oh, shit!" Reggie exclaimed, diving for cover as he sighted a blue-then-purple object headed right for them all on the balcony.

"I marked that about two miles out, Twilight!" Rainbow Dash said as she suddenly came to a stop in midair, freaking the hell out of Reggie.

"Hey, Reggie! You okay?" Rainbow thought to ask.

"So, this next move is my very own patented signature move, called the Sonic Rainboom!" Rainbow cheerfully told him before speeding off to prepare for it. He had to admit that actually seeing her perform was as good, if not better, than he experienced in the dreamscape. Even if he couldn't experience the colors that he remembered from his dreams, the color shifts from watching her swoop toward and away were just as incredible. Beside him, Twilight continued to scribble note after note, her quill giving almost an impressive display as the pegasus soaring through the sky.

"So, what is this 'sonic rainboom' again?" Reggie asked her.

"It's where Rainbow Dash breaks the sound barrier and ignites a burst of magic that is just amazing to behold," Twilight happily said.

"Breaking the sound barrier?" Reggie confirmed, as he sighted Rainbow getting ready for her dive. "Wow! I wonder how that's going to look like to my sonic vision."

But then his brain triggered a warning thought that quickly grew to extreme concern. And given the expression that formed over Twilight's face, her mind was giving her the same conclusions.

"Oh—shit," Reggie muttered as he saw Rainbow Dash's figure go to a full purple.

"No! No! NO! NO! NONONONONOOO!" Twilight began screaming. "It's too late to warn her off!"

Reggie tried to take cover as Twilight erected a solid green barrier over him just as Rainbow Dash's purple figure vanished.

Then the world exploded.

The world was black.

He couldn't make anything out of his surroundings.

There was an uncomfortable weight on his chest.

Shakily, he raised his arm to feel the thing laying on him.

It felt like a pony's head, with a thick mane.

Before he could make any further investigation, the weight suddenly lifted, pulling something from his chest. The pull felt familiar.

"Who's there?" Reggie croaked out.

"Oh, Reggie!" Rainbow Dash's voice called out from just in front of him. Or just above him, considering he could tell he was lying in a bed. "I'm so sorry!"

"Rainbow? Is that you?"

"I'm so-so sorry!"

"I—uh—I can't see anything."

"I know! I shouldn't have done it! I was such an idiot!" Rainbow cried, hugging him. "I should've known what effect doing a sonic rainboom would have on you!"