//------------------------------//
// To Tartarus and Back 
// Story: Irreversible 
// by Trick Question 
//------------------------------//

"The stars moved?" said Twilight Sparkle, her jaw agape.

"Yes. And, just to be clear, I am not referring to the rotation of the Celestial Sphere," said Moondancer.

"You're not referring to the rotation of the Celestial Sphere."

Moondancer paused, with narrowed eyes. "Twilight, this conversation will go much faster if you don't repeat everything I say."

"Oh. Sorry, Moonie."

"It's fine," said Moondancer, "I was in a state of shock initially, myself. Here." Moondancer pulled out several large maps from her saddlebags and splayed them across the Cutie Map. The holograms obscured most of the details.

"I'll just turn that off for a moment," said Spike, fiddling with Twilight's throne. "You do have a way to turn it off, don't you?"

"It does what it wants," said Twilight, shrugging.

"Floor, then," said Moondancer, levitating the maps and placing them on the floor. She sat down and gestured for Twilight to follow.

"I have some work to do and I probably won't follow half of what you're saying," said Spike. "I'll be transcribing in the library."

Twilight nodded, then turned her attention to the maps. There were five of them, two which she recognized immediately.

"Those are the classic 881 A.S. maps," said Twilight, pointing to them. "The two where seasonal aberration was first discovered due to the apparent motion of Neo 14. This is why we only make exact measurements during the Winter Solstice."

"Nope. They're accurate," said Moondancer. "The problem isn't that the maps are wrong, it's the sky."

Twilight furrowed her brow. "But it's the atmosphere that causes the distortion, isn't it?"

"I know that's what we're taught, but look here," said Moondancer, pointing at two other maps. "These two were done in 847, both in Summer and Winter. They're identical, and I've checked: they're every bit as accurate as a modern map. The measurements in Winter of 847 were made immediately following the invention of the filar micrometer."

"So they got lucky and the maps are coincidentally accurate..."

Moondancer shook her head. "No. I checked every stellar map made between 847 and 881. There were seven made, not counting these four. Each one is identical, with one exception in 873 where the map was kind of sloppy in general, but Neo 14 is still in the same location," said Moondancer. "Then the map made in Summer of 881 comes along, and bam: Neo 14 is off by a couple of micrometers."

Twilight paused in thought. "There isn't a seasonal aberration? But maps made after 881 confirm that measurements made in Summer are less accurate."

"Twi, the evidence I've uncovered suggests the seasonal aberration didn't exist prior to 881. And it isn't that Summer measurements are 'less accurate'. It's only Neo 14 that changes, and the change is predictable! I just measured it yesterday, here," said Moondancer, pointing to a freshly made map of a small portion of the sky.

"It doesn't seem to be off by as much... wait, that's because it's Spring," said Twilight. "Dear Celestia."

"Exactly. Neo 14 is located between the two extrema right now. This star moves, Twi. It moves every six months, and then it moves back," said Moondancer. "It's not the only one, either. I'm almost certain Traicere 27 moves too, only by about half as much. But again, not prior to 881."

"This doesn't make sense," said Twilight. "Even if it made sense for stars to move at all, why would stars start moving? These are simple scientific measurements of a fixed sphere."

Moondancer shrugged. "Oxcam's Razor. It isn't a perfectly-fixed sphere."

Twilight Sparkle wrinkled up her muzzle in distaste. "Prior to 881, all measurements are consistent with stars being tiny motes on a fixed sphere, and the last time the technology improved was in 847," she said. "If you're right, what you're suggesting is one of the greatest discoveries in the history of astronomy... but even if stars aren't motes on the Celestial Sphere, there's no reason why our measurements would suddenly change in 881. I wouldn't even know where to begin theorizing."

"Same here, so I threw away my assumptions and did a little timely research," said Moondancer, and she pulled out a book from her saddlebags. "This is a historical record of events from 881." She turned to a specific page and levitated the book to Twilight.

"Hmm? The Great Earthquake of 881," said Twilight, reading from the book. "The largest and strangest temblor in recorded history, with energy surpassing the Yottajoule range. No apparent epicenter, just a sustained rumbling across the entire world that lasted all night. We still don't know what caused it, but the prevailing theory—"

"—is a mana cataclysm, yes, I know. So this got me thinking: here's another unexplained scientific mystery, right? I wanted to understand what happened leading up to the tremor, so I looked at everything that happened the same day. See anything unusual?"

Twilight looked through the list of news items. "Mostly mundane stuff... Huh, this is weird: it was the release date for a book called Motus Discus by Early Dawn? 'A romance of astronomical proportions.' Wow, it sold over ten thousand advance copies... that's a lot for the ninth century. I'm surprised I never heard of it, but the author's name sounds very familiar."

"Based on the news item, it's a fictional romance novel about astronomy: literal star-crossed lovers. There aren't any copies of it in the Royal Library—nor on the manifest of the Manehattan Historical Library, for that matter—but I did manage to track down who Early Dawn was," said Moondancer. "I'd ask you to sit down if we weren't both on the floor already. He was the Royal Astronomer from 840 through 878, and the inventor of the filar micrometer."

A moment passed as Twilight digested the information. "That's bizarre. Even if it's only a romance novel, a popular work of fiction by the Royal Astronomer should be preserved for posterity. Why aren't there any copies in the Library?"

"I looked back at old manifests of the Canterlot Royal Library. They've never had it in stock."

Twilight made an abrupt laugh. "Surely they'd have ordered at least one!"

"Maybe they did, but if so, they never added it to the catalog."

"Weird," said Twilight. "But all I'm seeing here are more odd coincidences and questions. How does any of this tie together with the apparent motion of Neo and Traicere?"

"That I don't know, but something happened in 881, Twilight. Something happened to cosmic measurement."

Twilight stood up and walked back a step. "You're not suggesting what that sounds like!" she said, pointing at the maps with a hoof. "Science relies on the base assumptions that reality exists, is measurable, and that measurements are consistent from place to place and time to time. We can't throw science out the window!"

Moonancer stood up and walked over, grasping Twilight by one shoulder with a forehoof. "Of course I'm not suggesting we throw science out the window. But something changed, Twi. Either something about the Celestial Sphere changed, or something in how we conduct science... or else history isn't correct."

"Then it must be history," said Twilight, placing her hoof on Moondancer's. "I don't see how, but... I don't know what we can trust anymore." Her eyes shimmered, tears on the edge of forming.

"Well, I know at least one source I can always trust," said Moondancer, raising a bushy brow.

"What's—" said Twilight, shortly before being both answered and silenced by a kiss. A simple kiss turned into something deep and long. At least a minute passed before somepony behind them made a giggling sound.

Both mares quickly broke the kiss, blushed, and turned to see Pinkie and Rainbow Dash standing at the entrance to the room, with Spike behind them. Pinkie was grinning like mad, while Dash blushed and struggled in vain to fold her wings. Spike just stared with his jaw wide open.

"You two are SO CUTE together!" bubbled Pinkie Pie.

"Y-yeah. Maybe you can keep that to somewhere private?" asked Dash. "I mean, I'm not saying there's anything wrong with it, with you both being mares, and, and the kiss..." she added, her voice trailing off.

"I can't remember the name of the realm again," said Twilight.

"Me neither," said Moondancer.

"I can't remember my own name right now," said Spike.

"It's... a sneeze or something?" said Rainbow Dash, finally folding her wings downward. "Achoo?"

"Quifons!" said Pinkie Pie. "How could you forget that?"

"Being aroused appears to make you forget the name of the realm," said Moondancer.

"It's more than that... I forgot it the last time I took the potion," said Twilight.

"We need to do more research then," concluded Moondancer. "Maybe one of your friends could try thinking different things and feeling different emotions, and make a list of things that do and don't make you forget the name."

Twilight grabbed a piece of paper, then looked at Spike. "Spike, this upcoming conversation is not for little dragons. Didn't you have something to do for me? Remember?"

"Now I have two things I have to do," he mumbled.

"Then multitask!" said Twilight, rolling her eyes in exasperation.

"Twilight, I really don't think you want me combining... you know, I'm just going to exit the room now," said Spike, and then he left.

"Okay. I need the two of you to test as many emotions that you can think of," said Twilight. "Disdain, shame, ennui..."

"On what?" said Rainbow Dash.

Twilight sighed. "Here," she said, wrote down something on the piece of paper, and hoofed it to Pinkie Pie.

"Ooh! Doctor Yoke's Guide to Emotional States. That's in the library upstairs?" said Pinkie.

"Exactly. And not just emotions, but emotional activities too," stressed Twilight. "And write down the name of the place so you can remember it between attempts."

"Uh, why exactly did you have to kick Spike out to tell us this?" asked Dash.

"As many emotional activities as you can think of," said Moondancer. "Get it?"

Rainbow Dash frowned. "Sorry, eggheads."

Pinkie giggled and whispered something in Rainbow Dash's ear, and her wings launched outward, whapping Pinkie in the face. "What? W-what? I, I, I..." she stammered.

Pinkie picked Rainbow Dash up and placed her onto her back. "Don't worry Dashie, I got everything covered."

"Help me!" whimpered Rainbow Dash, bright red peeking through her cyan cheeks.

Twilight Sparkle reached out to help, but Moondancer blocked her with a hoof. "Twi, they'll be okay."

Twilight watched as Pinkie trotted out the doorway. "Rainbow was asking for our help..."

"From what I know of Pinkie, she'd never do something to somepony against her will," said Moondancer, "and did you see Dash's wings? They'll be fine together, really."

"What was wrong with her wings?" asked Twilight.

Moondancer blinked a few times. "Wow. And you're an alicorn now. Remind me to have this conversation with you later... though I guess you'll figure it out if we keep kissing," she said. "Ahem. Anyway, this is unimportant. Or less important, rather. We need to investigate the historical context of the stellar changes."

Twilight nodded a few times, then noticed her own wings had been extended the entire time she'd been talking. She quickly folded them back in place. "Right, right. But... I need to go to Tartarus first. The Map wouldn't be calling me if it weren't urgent. Moonie, can you tackle the research?"

"I can try, but I'm worried I've already spent too much time in the Royal Canterlot Library if we're trying not to arouse suspicion. I'll see what I can find here first," said Moondancer. "Then maybe I'll head for the Crystal Empire. There might be a clue in ancient history as well."

Twilight walked around the table until she stood in front of Applejack's chair. "I'd rather you not leave until Starlight Glimmer returns. You're the only mage I can trust to bounce ideas off of, not counting Zecora... and don't get me wrong, she's really wise, she's just—"

"Twilight, hold up," said Moondancer, standing on the other side of the table by Fluttershy's chair. "Don't you think it's strange that the Map doesn't have the leaves to it anymore, but it still behaves like it does?"

The young alicorn shook her head. "Everything the Map does is strange. I don't understand how it used to exist with the Sisters, and then it disappeared and somehow came back."

"Maybe they did something that made it angry. Er, not that maps get angry, but it seems to have a personality..." Moondancer stopped and narrowed her eyes. She leaned in toward the edge of the table facing Fluttershy's chair. "Twi, there's a discoloration here. Have you seen this?"

Twilight looked down at her side of the map. "There's a small spot on this side too. You don't think?"

Moondancer touched it with her magic. "Whatever it is, it resonates more than the rest of the table. I can't seem to match the frequency, though."

"I'm going to try something dangerous," said Twilight.

"I'd object, but I doubt that would dissuade you."

Twilight's eyes began to glow green, and black flames licked at the edges. "Dark magic," she said. "It has a wider band of resonance..." The darkness bubbled at the edge of the Cutie Map, and a ringing sound emanated from it. "It's working, but... it's missing something."

"Touch both sides?" asked Moondancer, looking around the rim. "I don't see the mark anywhere else."

"It's taking all my concentration to activate this one side—wait. Use magic on your side, then telekinetically link with my horn," said Twilight.

"Wh—are you sure?" asked Moondancer, blushing.

"Yes! I can't hold this much longer, just do it," she ordered.

With a stoic look on her muzzle, Moondancer grasped the edge of the table with her magic, then made contact with the dark aura around Twilight's horn. Darkness filled her vision, and she gasped.

Two things shot open at the same time: Twilight's wings, and the sides of the table.

Both mares were punched in the chest by the table leaves which seemed to emerge somehow from the empty space above the table, and they fell backwards into the thrones. A loud squeaking sound filled the castle as Applejack's and Fluttershy's thrones somehow slid backwards without breaking contact with the crystal flooring.

Both ponies dropped their magic. A blurry image of Quifons sparkled mesmerizingly in front of Moondancer, and she stared at it, transfixed where she had slumped over into Fluttershy's throne.

"Moondancer, look away," said Twilight, staring herself despite the imperative.

"I can't! It's... it's so beautiful," whispered Moondancer. Then Moondancer yelped as darkness surrounded her. "Twilight! Did you just blind me?"

"No, I just cast a sphere of darkness around that half of the table. Come over here," said Twilight, and her friend stumbled out of the dark.

"Wow. I didn't believe you when you said it was that gorgeous. I wanted to, but it didn't make any sense..." mumbled Moondancer, looking up into Twilight's eyes.

"Moonie, it's okay. It's indescribable. Although, oddly enough, I'm getting used to seeing it. I wasn't as strongly affected by it this time."

"Indescribable is an understatement. Look, Twi, we can't let you destroy... whatever that is."

"I know."

"Although... your eyes are almost as beautiful," said Moondancer, wearing a gentle smile.

The eyes in question began to water from emotion. "I, heh. Well, um, we need some way to cover the area when the spell ends, and I don't know if a normal cloth will obscure the hologram," said Twilight.

"Do you have anything anti-magic that could block it?"

"Oh! I know something that will work perfectly... except... horsefeathers."

"What is it?"





"Keep the Quifons wing of the map covered in the anti-magic cloth. Got it," Spike said to Twilight.

"And I certainly hope at some point you'll tell Trixie—I mean, me—just exactly what all of this means?" asked Trixie, wearing a frown. "I may be the most generous mage in all of Equestria, but that prop is an important part of my act."

Twilight Sparkle sighed. "I promise I'll tell you in due time, Trixie. And thank you for your generous contribution. Starlight is currently on assignment, and she'll probably want to clue you in once she returns."

"Aha! So that's what this is about," said Trixie, narrowing her eyes. "You sent your 'student' gallivanting across Equestria and you made her leave without even saying goodbye to me."

Twilight shook her head. "It's... look, I may be in the middle of something big."

"Big, exciting, and grand, naturally. Hmph!"

"No. Big trouble. Legally, morally, physically, you name it. I'm about to go to Tartarus, actually," said Twilight.

"Please, Twilight. I may have asked you to go there before, but that was a figure of speech."

A frown crossed Twilight's face. "You never told me to go to Tartarus, Trixie."

"Oh!" said Trixie, grinning sheepishly. "I must have thought it very loudly in my head. My mistake."

Twilight covered her face with a hoof and sighed. "What I'm saying is that I may be in trouble, and I've been trying not to get ponies involved, because they might get in trouble too. Do you understand?"

"Better than you know," said Trixie, with a grimace. "The Great and Powerful Trixie has earned her fair share of trouble. You have... my..." she added, then swallowed and slowly formed the word with her lips as though in great pain, "sympathies. But friends help each other, and if Starlight is helping you, then so am I." A sudden look of surprise crossed her face.

"Hay, I can't believe you said it either," said Spike.

Twilight nodded. "Thank you, Trixie. I guess if you can't wait, you can go ask Moondancer to cue you in. She's in the library upstairs. Just tell her I said you were involved now. There is another option, however."

"Which is?"

"Pretend none of this happened and you can claim plausible deniability if anything goes wrong. I don't want anypony else to suffer if something bad happens to me."

Trixie pursed her lips in thought. "If Starlight's in this, so am I. However, I'd rather hear it from her first, once she gets back. I'll play dumb for now, Twilight."

Twilight half-smiled. "I think that's probably best. I'm sorry if I end up getting you mixed up in this, Trixie."

"Well, you should be," said Trixie. "But, um... be careful in Tartarus, Twilight." Trixie turned and walked out of the castle.





Flames licked at the sides of the rock bridge Twilight Sparkle was crossing, making her sweat profusely. Tirek lay just a few paces ahead, but said nothing until Twilight was standing right next to him.

"What do you want?" he sneered.

"I don't know yet," said Twilight. "The Cutie Map sent me here."

"Cutie Map? Ah, you must mean the Map of Harmony." Tirek made a contemptuous face. "I never liked her."

"Who?"

"It matters not. I have no business with you, no matter what Harmony may think."

"Wait, do you mean Harmony? Is Harmony a person?"

Tirek sighed. "She is—or was—one of the Twelve."

"Who are the Twelve?"

"You know some of them already, so go bother them instead. The Sisters or that traitorous foal Discord could answer such questions. Or Star Swirl, though the last I heard he was trapped in Limbo."

Twilight thought better than to inform Tirek of Star Swirl's escape. "Look, the Map would not have sent me here if there wasn't something I could do to help," said Twilight.

"Releasing me is the only way you can help me, and I know you shall not do such a thing. But allow me to enlighten you on one subject. Harmony is not predictable. Perhaps she wants you to jump into the flames, Princess," said Tirek, spitting out the moniker like a piece of gristle. "I would enjoy seeing that." He lunged forward and snarled, the chains preventing him from moving more than a few inches.

"I'll bet," said Twilight, sweating for two reasons. "I don't know what I'm supposed to do here."

Tirek sighed. "What do you want, pony? I only want release or solitude."

"I want to know about..." Twilight began, then looked at the underside of her hoof to read the word. "Quifons."

A smirk quickly turned to uproarious laughter. "Of course you do. You and every adult on Theia. I shall tell you nothing."

Twilight frowned. "Then can you tell me why the sky changed in 881? Or what caused the mana cataclysm that same year?"

"I don't know when 881 is, or even which woof region of time you refer to," said Tirek. "Not that it matters."

Twilight blinked several times. "What the hay is a woof region?"

Tirek closed his eyes. "The world is far more complex than you are capable of understanding, stupid pony. I shall answer you no more."

After several failed attempts to move Tirek to speak, Twilight noticed her cutie mark blinking.





Arriving at the Castle of Friendship, Twilight Sparkle saw Starlight standing there waiting for her.

"Thank goodness you're back," said Starlight Glimmer. "We have a lot to discuss." The two friends walked into the castle and headed up to the library.

"I assume so. Is Spike here?"

Spike opened the door to the library. "Speak of the dragon, and his tail appears," said Spike. "Applejack taught me that saying, heh."

"Spike, catch me up on everypony's whereabouts." The group entered the library and sat down at a table.

"Okay, let's see. Fluttershy is still on mission. Pinkie and Dash are still working on whatever you told them to do—they've been holed up in Rainbow's Cloudominium since you left. AJ came back but she's at Sweet Apple Acres because they need help with chores since her absence, but Maud's in her cave waiting for you to contact her. Rarity's back and working in her Boutique, and Moondancer left for the Crystal Empire about an hour ago," he said. "I think that's everypony. Oh, wait. Zecora said she's turned up empty on clues for the creature that invaded the library."

"I spoke with Trixie," said Starlight. "She wants to be left in the dark until we need her, which is my preference as well. But I have a ton of information to catch you up on."

"Have you read my journal yet?"

Starlight nodded. "I'm current. Why don't you go first?"

Twilight briefly described her encounter with Tirek. "I have no idea what a woof region of time might be."

"Hmm. Well, in weaving, there are two directions of thread. The warp is the matrix of straight threads, and the weft or woof is the long thread that goes back and forth between them," said Starlight. "But time isn't anything like a tapestry. It's a single, curved dimension."

"Spacetime is a tapestry, but you don't need to talk about 'woof regions' to make sense of it," said Twilight. "Maybe it's an archaic way of describing spacetime curvature, assuming the Twelve knew about it long before ponies discovered it."

"It's useless to speculate with this little data," said Starlight. "Anyway, it's my turn."

"I'm all ears. Figuratively," said Twilight.

Spike rolled his eyes.

"I have the device, which I've managed to hold off on testing until we could do it together. It took a lot of magical shenanigans to get it, though. That museum is locked down like a vault, especially after what happened there," said Starlight.

"What happened?" asked Spike.

"Some kind of magical creature attacked the place at night. It was spotted outside by some ponies, but it mesmerized them. Based on their symptoms, they think it's the one who targeted the foals the previous night, as well," said Starlight.

"That's fortunate," said Twilight, with a sigh of relief. "I thought they'd trace that back to you when Luna told me about it."

"It wasn't me, Twilight. Rarity's disguises led ponies to think we were suspicious, but I never had the opportunity to approach any foals. Besides, I realized we could probably get parental consent to run experiments on foals here in Ponyville if we're clever about how we do it," said Starlight. "Whatever the creature is, it has to be what caused the foals' amnesia. But here's the really weird thing. I used a spell to peek at the markings inside the museum after they closed it off to the public—they put down tape marking where the hoofprints were—and it was right around the locations I'd been at earlier that same day."

"That's strange... What day did this happen?" asked Twilight.

"I know where you're going with this, and yes. It was the same night that the creature invaded Celestia's quarters, in the middle of the night."

"Manehattan is too far away from Canterlot for a creature to be in both places at roughly the same time," said Twilight, shaking her head. "We need to rethink this. Even Rainbow Dash... no, she could probably make the distance, but she'd be totally exhausted and it would take her too long. I'm not even sure Celestia could pull it off with a series of long-range teleports."

"Either we're dealing with an invasion of similar creatures, or this one beast can move from place to place as fast as a sound wave," said Starlight. "Good grief. I'm not sure which possibility is worse."

Twilight put on a brave face. "We'll need to hurry. Let's go see Maud, then we can try the manamomonometer."