Twilight knew she was there instantly, before she’d even opened her eyes. The room had that same cavernous silence. That same heavy, almost tangible atmosphere of mountains of knowledge. That same musty smell. That same surprisingly pleasing feeling of demons being eternally frustrated. She opened her eyes.

She was in the foyer of the Library of Babel. Bookshelves stretched up to ceiling, miles away. Aisles ran to infinity and beyond. Each and every inch of each and every shelf was positively stuffed with books. The sole reason Twilight didn’t hear a heavenly choir of angels was because she was in hell. (Maybe the angels were still navigating the bureaucracy.) She wouldn’t even have minded an infernal choir of demons.

She was about to pick her first few books when something in the corner of her vision caught her eye. Words hung in the air, strange glowing symbols that Twilight somehow instinctively understood, even though she’d never seen them before.

“Oh, sure,” mumbled Twilight. “Now that it’s properly set up, they use it freely, but they don’t mention that I’m the one that set it up!”

But her discontent was gone in seconds. She was here. She could find anything. She double-checked the locations of a few books. Yes, her system was still in place. Excellent. She teleported around the foyer with pops and blips; even this relatively small space had plenty of books worth reading. Cross-temporal nonfiction, mostly. She picked up Puddinghead’s diary, Celestia’s autobiography from the future, her own autobiography from the future, her own autobiography from the future in a timeline where she was born a kirin and ascended to a kirin-batpony-crystal pony alicorn, a collection of love letters between Daybreaker and Nightmare Moon-

Starlight coughed and groggily crawled to a seat. She stared up at the room above, trying to take it all in. “So, this is it? The Library of Babel?”

“Yep! Although, since it’s organized, I guess it should technically be the Akoltshic Records now, but oh well.” Grinning broadly, Twilight dropped her pile of books on the nearest table. “Isn’t it great?”

“You’re saying that somewhere in here is every book possible?”

“Absolutely! I’ve got it all categorized.”

“Philosophical treatises written by drunk sororfillies?”

“Uh-huh.”

“Daring Do books with author’s notes?”

“Yep! Including the ones that haven’t been published yet!”

“My life story, beginning to end?”

“And mine, too. I’ve got two versions here! See?”

“All of Starswirl’s works, only with every noun replaced with ‘chicken’?”

“I actually read the ‘watermelon’ version of one of those.”

“Romantic fiction of me and you?”

“Totally.”

“…Porn of me and you?”

“What part of ‘every book possible’ don’t you understand?”

“Okay, fine.” Starlight dropped to her rump and crossed her legs in annoyance. “You know where everything is. Where’s the book about what’s happening to us right now?”

Twilight tapped the floor for a moment. “Okay, you see that spiral staircase over there? Take it thirty-nine stories up, go fifteen feet to the right, go left for twelve hundred-”

“You’re kidding.”

“Am not! Want me to get it for you?” Twilight vanished in a spark of teleportation and reappeared a few seconds later, levitating a very short novella in front of her. “Here.” She tossed it to Starlight.

Catching it, Starlight examined the cover, a laughably amateurish effort of crudely-composited photos that didn’t even have the author or title on it. She glanced at the spine. “Uh… Heaven of a Hell, by Rambling Writer. Who’s Rambling Writer?”

“Dunno. That’s just the author of that particular permutation. They might not even exist.”

Starlight rolled her eyes and cracked the book open.

“Starlight?”

“Yes, Twilight?”

“I need your help. I’m going to hell.”

Starlight blinked. Okay, that was… Maybe this was the book of now. She flipped forward a few pages.

“ ’Tis a part o’my torment. Them demon punts installed a funkin’ profanity filter or summat.” The sailor sighed. “I tell ya, d’ye know how funkin’ hard ’tis t’be a funkin’ sailor an’ not able t’funkin’ curse all proper-like? Buffer ’em. ’Tis funkin’ hell.”

“I think that’s the idea,” said Twilight.

Déjà vu began to creep over Starlight. Okay, one last look, then she’d be convinced. She went ahead a few more pages.

Starlight rolled her eyes and cracked the book open.

“Starlight?”

“Yes, Twilight?”

“I need your help. I’m going to hell.”

Starlight blinked. Okay, that was… Maybe this was the book of now. She flipped forward a few pages.

“Gah!” Starlight pitched the book across the room.

“Hmm?” Twilight asked as she trotted over to a table with another stack of books.

“I’m at now!”

“That’s usually the case.”

“I mean in the book! I’m at now!”

“When?”

“Now!”

“You’re at now now?”

“Yes! Now!”

“If that weirds you out, then go back to then.”

“I did! I already passed it.”

“When?”

“Now.”

“Now?”

“Now!”

“Not then?”

“No, I was at then just now.”

“Then you could go past both then and now to later.”

“Now?”

“No, later.”

“Go to later later?”

“No, go to later now.”

“Why now? Why not later?”

“Well, if you don’t go to later now, you’ll be going to now later, because later will be now then. And now will be then later, I guess.”

“…When will later be now?”

“Soon.”

“…How soon?”

“Well, it might be later. It depends on how soon later is.”

“But later will be now eventually, right?”

“Yes, but not until later. Or maybe sooner.”

“…My brain hurts.”

“Yeah. In here, that happens every now and then, sooner or later. Read this.” Twilight tossed another book at Starlight: So You’re Learning About the Library of Babel and Recursion Makes Your Brain Hurt and Your Partner Has Already Adjusted — What to do About It (Especially YOU, Starlight).

Starlight stared at the book. Everything. “So, uh, where’s the catalog?”

Starlight was halfway through a chronicle of Big Mac marrying Sombra — who knew apple pies were the key to morality? — when a tiny little problem occurred to her. “Hey, Twilight? How long have we been in here for?”

“Dunno,” Twilight said with a shrug. “Now, shush. Changeling Blueblood’s about to-”

“So now that we know where this place is, shouldn’t we get back to Equestria? Just to check in?”

Twilight looked up, her flabber thoroughly gasted and then some. “Are you crazy? Now? We just got here!”

“And you’ve read a thousand books in the meantime!” Starlight pointed at the carefully arranged ten-by-ten stacks of ten books each next to Twilight.

“Not quite a thousand, unfortunately. See, these three stacks are all missing a few books. And we’ll arrive back in Equestria right after we left.” Before Starlight could ask the obvious, Twilight had conjured up a blackboard and was scribbling complex equations on it. “It’s easy. Knowledge is power, right?” Scribble scribble.

“Okay…”

“And power is energy divided by time.” Scribble scrawl scrawl.

“Wait, I think you’re talking about two different-”

“And energy divided by time is matter divided by time.” Numbers scribble scribble!

“Yeah, you’re definitely-”

“And matter divided by time bends spacetime divided by time, which is just plain bending space, while time has been divided out of the respective region.” Scribble diagram diagram ERASE diagram!

“I kind of doubt-”

“Sooooooo…” EMPHATIC. CIRCLE. Twilight grinned and proudly swept a hoof around the library. “This much knowledge in one place effectively nullifies the passage of time in an outer reference frame. We’re experiencing time dilation so extreme that we can spend years in here without so much as a single instant passing in Equestria. Not only that, but space is so warped that, in higher dimensions, everything is more or less folded on top of itself in three dimensions, allowing easy, instantaneous teleportation to anywhere in the Library’s infinite space!”

“But if that’s true, doesn’t that mean the owners of those independent bookstores are time travellers from another universe?” Starlight frowned. “Wait. That explains a lot.”

Twilight pushed the blackboard away. “So, short version: we can spend as long in here as we want without worry.”

“So long as you’re out in the next ten minutes.”

Starlight and Twilight both turned towards the rumbling voice. “Oh,” said Twilight, her voice going as flat as undrunk soda. “Hello, Beelzebuck.”

Beelzebuck paid the greeting no mind. “Mortal, you must-”

“Beelzebuck, Starlight. Starlight, Beelzebuck,” Twilight said in a bored voice, gesturing back and forth. “Say hi, Starlight. Or have you met?”

“Um.” Starlight slowly lifted a hoof up and twitched it, grinning nervously. “Hi? I’m… Starlight Glimmer, and, uh-”

“The two of you,” snapped Beelzebuck, “are not welcome here.”

“Say hi, Beelzebuck. Don’t worry, Starlight,” Twilight stage-whispered, “his bark is worse than his bite. Although, considering his bite is acid-laced…”

“Thank you for that spectacular reassurance,” Starlight whispered back.

“Anytime!”

“Both of you,” said Beelzebuck, pointing at them, “are trespassing. You are not allowed in here, and I’m giving you ten minutes to depart.”

“But whyyyyyyyyyyy?” moaned Twilight. “All we’re doing is reading! And building book forts. Like that one behind you. I mean, check out the turrets!”

“For starters,” rumbled Beelzebuck, “you’re not dead.”

“That’s easy to get around. Watch this!” Twilight’s horn glowed for a few seconds, then she slumped limply to the floor. Or, to be more precise, her body slumped to the floor. Her soul remained standing and smirking, only slightly less solid than her body. “I’m dead now. Happy?”

Starlight glanced up from her book and raised an eyebrow. “Impulse control isn’t a strength of yours, is it?”

“Oh, hush,” said Twilight’s soul. She waved a hoof dismissively. “It’s just self-induced cardiac arrest, so the body’s largely intact, and thanks to the liminal nature of hell, it’s way easier to reverse here than it is back in Equestria. I just…” Her horn glowed again and her soul dissolved into glowing particles that rushed back to her body. She immediately stood up, looking as peppy as ever. “See?”

Beelzebuck clenched his jaw with a might that could turn coal to diamonds. “Leaving aside your life signs or lack thereof, this is not a public library.”

“Mind if I just keep reading until you sort this out?” asked Starlight.

“Aw, come on!” protested Twilight. “I’m, like, the number one donor for this place! I deserve an exception.”

“Leave, or I will be forced to remove you from the site,” said Beelzebuck.

“Guess not,” said Starlight. “I’ll stay quiet.”

“You do that,” Twilight said slyly, “and I’ll tell Satanner all about the Cheez Whiz Incident.”

Beelzebuck crossed the space between them instantly and pinned Twilight to a shelf by her neck, his form writhing in combined anger and fear. “How do you know about that?” he roared. “Paimane gave his word that it wouldn’t get out!”

Twilight simply smiled and levitated a book from a stack. She showed it to Beelzebuck: The Big Bad Book of ALL the Blackmail, by Everyone, Anywhere, Ever. “I know my system,” said Twilight. “It’s a very good system. And this book is very comprehen-”

Beelzebuck snatched the book from the air and threw it down. Before it’d even touched the floor, it burst into flames, and it exploded into ash once it hit the ground. Panting heavily and sneering, Beelzebuck said, “And what will you do now, now th-”

“Oh, wow,” sighed Twilight. “You’re new to this, aren’t you? A, I still know about the Incident. And B, that was just one of many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many…” She took a breath. “…many, many, many, many, many, many, many, many, many, many, many, many, many editions of that book. Specifically, there was a printing error on page 31852, where ‘will’ was spelled with one L instead of two.”

Beelzebuck’s chest heaved. Smoke trickled from his ears, but it was ambiguous whether that came from pure anger or his brain malfunctioning. Twilight stayed limp in his grip, smiling happily at him.

Then he squeezed Twilight’s neck until it snapped like a petulant diva. “No more pony,” he hissed, throwing her body to the floor, “no more problems.” He vanished in a puff of brimstone.

“Twilight!” Starlight yelled, running to her body. “Twil-”

Twilight’s soul stood up from her body. “Huh,” she said, staring at her body. “Probably should’ve seen that coming. Hey, can I see the book of now?”

“You’re dead!”

“I figured as much, unless that’s my secret twin’s dead body. Now: book! Gimme.” Twilight trotted through Starlight, swiped Heaven of a Hell, and flew to a table to start reading it. “I gotta come back somehow, right?” she muttered.

“Okay, Starlight,” said Starlight, jumping from hoof to hoof as she stared at Twilight’s body. “It’s time to bring your teacher back to life! Somehow. In hell. When you don’t know any necromancy, and not for lack of trying. Why couldn’t my field trips have been to someplace safer, like the center of Equus? But there’s a catalog, right? So I just-”

“Oh, wow. Still looks nasty.”

Starlight looked up. Twilight was standing over Twilight’s body, tutting in disapproval. “Short version, time travel,” new Twilight said to Starlight. “I was resurrected by myself from the future, so I learned time travel so I could go back in time and resurrect myself in the past.”

“…And you also learned resurrection magic in the process?”

“Well, yeah. I’ve had plenty of time to practice it. Time travel? Doy?” New Twilight hit herself on the side of the head and made a face at Starlight.

“…Do I learn either?”

“Not only that, you learned the resurrection magic first, since you got to watch this me perform it on that me and see exactly how it’s done, so you’re going to teach that me to do it, so when that me becomes this me-”

Starlight stepped back and rubbed her temples. “Just resurrect yourself.”

“You have no appreciation for information paradoxes, do you?” huffed new Twilight. Her horn sparked; old Twilight’s neck stopped looking like a broken pencil and in a gust of wind, her soul was yanked from two tables over.

Old Twilight sat up straight and stared at herself. After a second, she asked, “Time travel?”

“Time travel,” new Twilight said with a nod.

“You could’ve waited, like, three seconds,” old Twilight scowled. “I was just at now, and to get pulled away right then-”

“I know!” said new Twilight. “It was so annoying, I had to take revenge on myself for doing it. But don’t worry, it gets better. You didn’t even get to the part where you use porn to help convince Trixie to fight for you in a war.”

“Whoa, hey!” yelled old Twilight. She pinned her ears down. “Spoilers!”

New Twilight stuck her tongue out at old Twilight. “Nerrrrrd.” She vanished with a pop.

Twilight glared at where her future self had been, but started smiling again. “Well! Back to reading!”

“Don’t get too comfortable,” said Starlight. “Once that Beelzebuck guy knows you’re still alive, I bet he’ll come after you somehow.”

Twilight laughed. “Don’t be ridiculous. What could he possibly do?” She bounced back over to her book pile, humming something.

Starlight nervously retrieved Heaven of a Hell and skipped to the new now. Sure enough, there was a chapter break one short paragraph after Twilight said that. How clichédly ominous.