Mr. Black garnered quickly that the book he was reading wasn’t going to be much help. The Yakstanian Diet mostly covered a variety of vegetable dishes and how to properly grow food in winter climates. He tossed the book on top of three other books in front of him that he dubbed his Useless Stack. Next to the Useless Stack was the Not Quite Useless Stack, which had two books in it. Next to that one was the I Think I’m Onto Something Stack. This one had none.

Mr. Black reached to the left for his Pending Inquiries Stack, grabbed another book, and laid it open in front of him to the first page. He started with the table of contents, then moved on to the text. It must have been half an hour before he decided that the book had nothing of value to offer, so he shut it and set it in the Useless Stack.

This process was repeated three more times. A normal creature would have yawned at the mundanity of the task, but then again, not every creature had the mental fortitude he had. This was the most relaxation Mr. Black had had since the train ride into town, and even that was spent going over the report given to him and running through several procedures in his head.

When he figured that the next book also didn’t have anything resourceful to offer, he chucked it onto the Useless Stack and reached for another book to his left. He laid it down in front of him, examining its cover. Its title was intriguing, and he was sure that he had heard about it at some point during his training courses. It was never discussed— if so he would remember. But there was that one offhand reference when his college professor was jabbering about Black Swan Theory.

Mr. Black opened the book and began reading the prelude.

Changeling Theory: An Analysis on the Origin and Influence of the Equestrian Changeling

by Aster Blackwillow

Introduction
When a pony is born into this world, they do not always enter it alone.

When a pony is first shunted out into the blinding chaos of this mortal life, there is a chance that another life enters alongside them. Unseen by onlooking midwives or parents, distracted as they are, it creeps out from the shadow of a new life’s gift. As a young filly cries out in confusion, and in terror, as the thread connecting them to the bliss of the womb is severed, this second life enters the world silently. Calmly. It scans the blinding light of the world not with the fear of its twin, but with insatiable, hungry greed.

And, quickly, crawling upon motes of dust, or within the veil of shadows, this creature slinks away into the world unseen.

This creature does not journey far. It watches from the glints of light just outside of our peripheral gaze. It perches in every dark corner of the room, driven by the same hunger it has felt since entering this life. It is the glimmer of movement one can never be quite certain they truly saw. It stalks its twin, never seen, but often felt by any lonely soul who might find themselves watched from within an empty room. Though a floorboard may creak, or a light breeze may send a curtain on a slight wayward wave, its twin will eventually sigh, or laugh to themselves for their foolishness, and turn away once more to their own mortal distractions.

And safely hidden, the creature will continue to wait in silence.

There will one day come a time in this pony’s life when the creature will cease its waiting. Sometimes, it will spend decades stalking its twin from the peripheral. Watching as its twin grows, and learns to navigate the strange world they share. The creature perhaps learns, too, of the world it can never truly inhabit by its own hooves. Other times, however, the creature’s patience endures moments, and it strikes at the same moment the infant enters the world. Perhaps the infernal wailing of its twin is enough to drive it into action. Perhaps it simply does not care enough about its world to bother learning how to inhabit it. The desires of the creature seem as inexplicable as the very nature of its being.

When this creature’s patience ends, so too does the life of its twin.

And, so too, does the creature’s own life begin anew.

Around them, the world carries on uninterrupted. Nary a leaf rustled, nary the sound of a hoof scuffing against the ground. From dust, the creature has emerged, and to dust its twin returns. And from the same pony’s eyes, the creature looks out at the life it had been watching. A faint glint of green may shimmer in its irises for but a moment, perhaps indistinguishable from a simple trick of the light.

Thus, changes will occur. The lives that the twin has known may notice a behaviour change. Depending on how patient the creature has been, these changes may not be detected for years, if at all. Slight alterations to attitude, to preferences, to interests, and nothing more.

Or, the changes may be dramatic. To the friends of the creature’s twin—madness. If the creature has chosen to strike the infant foal, then no change will ever have truly occurred to anypony but the foal themselves.

But at the moment of the hunt, nothing has truly changed to the outside world. For nopony has seen the creature strike.

A pony’s hoof has entered the world, and the creature’s hooves will continue the pony’s stride without a missed beat.

And into the world, fueled by the same calm precision that had framed its waiting, The Changeling emerges.

Mr. Black slammed the book shut and threw it into the I Think I’m Onto Something Stack.

~•~

"Want one?"

Sandbar scowled at the cigarette in Gallus's hand. "Where did you get that, dude?"

Gallus shook the pack of Cherry Delights: Classic in the pony's face. "Smolder sold it to me. The school regulates it for her because the smoke helps her respiratory system. Her words were, 'Something something dragon anatomy slash shitty cigarettes helps my immune system since pony air is too clean.' Sounds like BS to me. I think she stole them."

He held the cigarette in his other talon out toward Sandbar and repeated, "Want one?"

"We're in the library, bro," the pony bit.

Gallus held both of his talons up defensively. "I didn't mean you have to smoke it now. You can wait until we're at the Treehouse.”

Sandbar shook his head in disapproval. “No. I don’t want one. Put that away before somepony sees it.” Normally, he tried his best to use the “somecreature” pronoun in place of the common “somepony” pronoun, but all concerns for punctuality went out the window the moment contraband was shoved in his face. He had a right to be concerned. Even holding a cigarette on school grounds was an offense worthy of suspension.

Gallus, however, seemed to recognize that he was stretching the line. He slid the cigarette back into the packet and stuffed it down his sweater. He laid both of his talons down on the table in front of him. They were in one of the cozier parts of the library, unaware that somewhere on the other side, Mr. Black was doing his research. It was sectioned off by four surrounding bookshelves. While Gallus playfully tapped his claws against the table’s surface, Sandbar slouched back in the beanbag chair in the corner and sighed loudly.

“Why aren’t you upset, dude?”

Gallus stopped tapping. “What?”

Sandbar slapped his hooves to his lap in frustration. “Why aren’t you upset about what happened on your date with Silverstream?”

“Eh,” Gallus shrugged. “Shit happens. We can try again during the break, probably.”

“What if she wants to go home during the break? I don’t think Silverstream wants to be cooped up at the school all year long.”

“I’m pretty sure she doesn’t mind staying for a little while longer.”

Sandbar raised his head from the beanbag chair. “And if she does?”

“So she doesn’t want to stay at the school for the break. No biggie.”

“I think it is a biggie, my dude. You just asked her out and you two are already about to be separated for two weeks. Why don’t you try going with her to Mount Aris?”

“I barely wanted to travel to Ponyville. You think I want to travel across the country to a place that’s surrounded by the ocean? I can’t even swim! Besides, it’s too cold to leave town. I’d rather go during the summer.”

Sandbar sat up, his face scrunched into a stark scowl. “You have a lot to learn about this relationship thing.”

Gallus quirked a brow. “What do you mean?”

“You can’t just do whatever you want anymore. You have a girlfriend. You do what they want, now.”

Gallus scratched at the neck feathers below his beak. “I don’t get it.”

Sandbar reeled his head back and groaned toward the ceiling. “Look,” he said, uprighting his head again. “You’ve seen how Yona and I are, right?”

Gallus nodded. “Yeah.”

“Relationships are a full-time thing, my dude. If you go off to do your own thing, she’s going to get tired of you pretty quick.”

This time it was Gallus’s turn to groan. He rubbed the back of his neck, letting out the sound from his beak for several long seconds and shifting in his pillow uncomfortably. “Nocreature told me that was part of the agenda.” He placed both talons on the surface of the table in front of him and began to inattentively drum against it.

“Where is she now?” Sandbar asked.

Gallus stopped drumming. “In her room. We broke off after we hit the school. She looked pretty depressed.”

“So you left her alone, then.” It wasn’t a question. It was a simple acknowledgment that…

“I fucked up, didn’t I?” Gallus interposed.

Sandbar responded with a slow yet curt nod.

Gallus groaned again, laying his face against the table, both talons clenched into a fist alongside his head. “I’m gonna have to talk to her, aren’t I?”

“Yep,” Sandbar said casually.

Gallus sat back up. “Right,” he said. “I think I’ll go do that now.”

He stood up and turned, but as he made his move to leave, Sandbar called, “Wait! Dude, we were supposed to talk about how we were going to get to the castle for movie night, remember?”

They had thought that the snow would die down by now, but then Ponyville Weather Station announced a forecast of snowfall for the rest of the week. That made transferring his grandfather’s old sixteen-millimeter projector difficult.

Gallus turned his head slightly, acknowledging the pony’s presence but still clearly distracted by his own current agenda. “Yeah, yeah, there’s a shortcut in the caves beneath the school. We can move the equipment through there.”

The griffon immediately disappeared behind a bookshelf.

“Wait, dude!” Sandbar called for him again. “What happened to Professor Oinkals?”

When he realized that he wasn’t going to get a response, he leaned back into his beanbag chair and sighed.

~•~

“Silverstream!” Ocellus exclaimed, sitting up in bed and clapping both forehooves to her cheeks. “You’re wearing your emotional support sweater! What’s wrong?”

Silverstream looked away from the opened armoire, her What Happens In Las Pegas, Stays In Las Pegas sweater draped over her right foreleg. At first, Ocellus was asleep. She heard some rustling on the other side of the room and guessed that it was Silverstream coming back from her date with Gallus. However, when she opened her eyelid a smidge to see what the hippogriff was up to, she was shocked into wakefulness by the sight of the emotional support sweater.

Silverstream’s emotional support sweater was very fluffy and bright mustard yellow. It had a picture of an egg — sunny side up — on its front with the words I’m Eggcellent! stitched in colorful pink cursive above it. Silverstream liked this sweater because it was soft and because eggs are delicious.

“Nothing,” Silverstream said plainly. “I just felt like changing. What’s wrong with that?”

“Well, nothing. But you only wear your I’m Eggcellent! sweater when you’re upset about something.”

The hippogriff shrugged and chucked the previous sweater she was wearing into the armoire. “I guess I just felt like wearing it today.” She shut the double doors and threw the latch over the handles. “It’s snuggly.”

The changeling patted the empty spot next to her on the bed. “Do you want to sit?”

Silverstream looked away banefully. “Do you have something you want to get off your chest, Ocellus?”

Ocellus stared at a Silverstream for a second too long. Did she… did she know? No, she couldn’t. Ocellus was the only one to know that Lemongrass had di— even thinking about it made her lightheaded. Maybe telling Silverstream would help her stave through it? If the hippogriff knew, then she was probably waiting for Ocellus to spiel first.

She opened her mouth, ready to say it — all of it, but then a quick rapping at the door stopped her.

“I’ll get it,” Silverstream said, already walking toward the door.

She blinked in surprise to see Gallus standing behind the door. “Yo, what’s up?” he said.

Silverstream scrunched up her face in confusion. “What are you doing here? I thought you had planning to do with Sandbar.”

He shrugged. “We finished early. Besides, I wanted to come check on you. You seemed a little upset.”

“A little!” she exclaimed. Gallus flinched back a little at the sudden waver in her voice.

A-ha! Ocellus thought triumphantly. I knew something was wrong!

Silverstream halted, probably realizing that she gave too much away to the changeling in just a single sentence.

“I knew you were upset by something!” Ocellus blurted, pointing at her.

Silverstream lowered her head and sighed. Looking back up at Gallus, she whispered, “I think we should tell her that we know.”

Gallus raised a brow. “Are you sure?”

“She’s probably going through a lot of emotions right now. She needs to let loose.”

Gallus looked past her and toward Ocellus, who was looking back at the two of them in confusion. He nodded. “Fine.”

Silverstream stepped aside to let the griffon in. He closed the door behind him and began to pace frantically around the room. “Shit,” Ocellus could hear him muttering under his breath. “I’m not good at this sort of stuff.”

“I’ll start,” Silverstream offered. She looked back at the changeling and pointed at the spot next to her. “Is the offer still up to sit with you?”

Ocellus nodded slowly, confused about what they were going to say to her. Silverstream took a deep breath and sighed. She sat down on the bed next to Ocellus, who looked from Gallus and back to her. She swallowed. The silence was already getting uncomfortable, but for Ocellus, it was even worse. Deep down inside, she knew what this was about. She knew that they would somehow find out on their own.

“So,” Silverstream finally spoke. “We know that Lemongrass is dea—” she choked on her own words, eyes gleaming. She tried again. “We know that Lemongrass is d—” she choked back another sob.

“Lemongrass is dead,” Gallus finished for her. “We know about it.”

The hippogriff shot him a glare. He simply looked at her in confusion and mouthed, “What?” at her.

Ocellus wasn’t fazed by his bluntness. She did, however, sigh at the revelation. “Yeah, I found out the other day.” She shivered. “I can’t get it out of my head.” To Silverstream, she probably thought that she was referring to the simple knowledge that someone she knew was dead. Ocellus meant the corpse in her dream. Not just that, but the corpse she saw in her vision when she touched Starlight. It was plastered in her mind, forever embedded.

Silverstream placed a talon on her shoulder. “Why didn’t you tell us?”

“Headmare Starlight made me swear not to tell. Anyone. It would have caused a massive freakout, because —” she cut herself off. Did she want to tell them that a deranged killer was going about chewing off heads? No, Headmare Starlight was right. Her friends would only panic. Ocellus didn’t want them to do that.

“Because what?” Silverstream insisted. Her talon felt warm against her shoulder.

Ocellus was good at coming up with lies on the spot. It was part of her upbringing in Queen Chrysalis’s hive. To be a member of the hive, one had to be a good actor. To be a good actor, one had to be a good liar.

Her mind went blank.

Ocellus blinked. She opened her mouth, ready to spin a whole slew of words together that would sound satisfying to anycreature. Nothing. Nothing came out. She tried to think, and all she could come up with was nothing.

Ocellus was quiet long enough for Silverstream to cast a nervous glance back toward Gallus. He shrugged. The griffon stepped forward and lowered to his haunches in front of her.

“Do you want to tell us?” he asked.

Ocellus didn’t look at Gallus directly. She looked at the doorway behind him that led into the bathroom. She could see her reflection in the mirror. It nodded back at her with a sneery grin.

“No…” Ocellus mumbled although she didn’t know who or what she said it to.

Gallus tilted his head much like a confused dog. “What?”

Her eyelids fluttered. For no reason in particular, Ocellus suddenly found Gallus’s face to be very annoying to look at.

“I said no.” The words came out clear and simple this time.

Gallus blinked, looking petrified by her bluntness. “Well, can you —”

“Can you shut the fuck up?”

The room grew quiet. Silverstream held her breath, and Gallus barely moved a muscle. It got to the point where Ocellus could hear both of their heartbeats.

“Why don’t you…” Ocellus got down from the bed, standing nose to beak with Gallus. She jabbed a hoof into his chest. “Back the fuck off, ‘kay? This is my business, not yours. There was a reason I didn’t want to tell you, and I expect you to respect that reason. Kapeesh?”

Gallus tried to blink out some of the spittle that flew into his eye. “Say it, don’t spray it. Geez…”

“Ocellus, what’s got into you?” Silverstream asked. Ocellus felt a talon wrapping around her right foreleg, but she slapped it away.

Silverstream pulled her talon back with a hurt look.

“Get the fuck out,” Ocellus said calmly. An eerie silence filled the room as both Gallus and Silverstream remained cemented in place. She acknowledged neither directly, but she didn’t have to look at their faces to recognize the dread in their eyes.

Gallus continued. “Ocellus, are you —”

“Get out!” she screamed. Sitting on her haunches, she used both of her forelegs to push Gallus as hard as she could. He fell to the ground belly-up with a huff. Ocellus was a little relieved that he didn’t land on anything hard, but all feelings of empathy quickly receded. “Get out! I want to be alone.”

Silverstream hopped off the bed from behind Ocellus and tugged Gallus’s arm. “Let’s get out of here,” she said.

Gallus rolled onto his stomach and stood up. He took a step toward the door and stopped. He looked back at Ocellus, a scowl etched into his face. After a few too many seconds, it softened and he mumbled, “Hope you can make it to movie night.”

The two left the room after that. Ocellus was now all alone.

Stupid mutt and her orphan boyfriend… she thought. Ocellus held her breath. What was she thinking? She would never say anything like that about her friends! But, she said several things like it just then.

Her mind cleared — somewhat. Now it was running a million miles an hour. Every thought was followed by another. Every wholesome thought was discouraged by anxiety. She did it. She swore at her friends and pushed Gallus onto the ground.

Ocellus looked back up at the bathroom mirror, but her vision was blocked by something in the doorway. She gaped in shock. It wasn’t something, it was someone.

And that someone was Ocellus, looking back at her herself with a sinister sneer.

Author's Note

A very special thank you to NorristhePony for writing the Changeling Theory exert at the beginning of the chapter.

For those who are curious about why this chapter took so long to push out, it's because there are two more almost ready to be published. This one right here was meant to be the end of the first act, but then I saw the word count... well, l'll just say that 16,000 words would be difficult for the average reader to trudge through. Expect more very soon!