"I'm a little concerned by your recent Cutie Map mission," said Starlight Glimmer, chatting with Twilight Sparkle on the way to Maud's cavern.
Twilight picked up the pace to a trot. "You mean the fact that it sent me to Tartarus?"
"Not that," said Starlight, matching pace. "The Map sends us to friendship problems, without exception. Why would it send you to Tirek and then bring you back after a brief conversation? It doesn't make much sense."
"I was thinking about that, and I have a couple of theories. The first one is that the Cutie Map is somehow part of this Harmony person, and Harmony may have a personal stake in ensuring that we learn more about Quifons. We already have ample evidence that the Tree of Harmony is highly intelligent."
"That's sensible," said Starlight. "If there's an intelligent force behind it, the Cutie Map would certainly be capable of extending beyond a single purpose. I still don't like our data on the Map doing a one-eighty, though. What's theory number two?"
"I solved Tirek's friendship problem," said Twilight, shrugging. "Maybe it wasn't apparent, but talking to him may have been the catalyst needed to resolve a conflict between him and another of the Twelve. The Map called me back before the problem was fully resolved, but after I had done all that I needed to do."
Starlight huffed. "I don't like that hypothesis either. Resolving any friendship problem with Tirek would require a major change in his personality. I doubt it would even be possible, to be honest. Besides, it doesn't seem like you did anything to help him or anypony else."
"You're right. I think it's more likely the former theory," said Twilight. "Consider the fact that the Cutie Map has never sent us to Tartarus before, or to anyplace off of the main map. This was already a special case."
"Maybe," said Starlight, as the pair slowed down and walked into Maud's cave. "I'd still feel better if we knew more about Harmony. We should make that a priority the next time we speak with Princess Luna or Discord."
Twilight Sparkle and Starlight Glimmer sat on a mossy patch as Twilight finished a brief update. "That's pretty much all that's happened, though I've left out some of the details. We're curious about Rockhoof. Was anything out of the ordinary during your visit?"
"Rockhoof knows rocks," said Maud Pie. "I would have stayed longer, but I learned something I needed to share with you."
"What's that?" asked Twilight, shifting and reshifting how she sat against the moss.
"It's strange. He knows all about geology, except for one major detail. He had never heard of or seen a metamorphic rock before," she replied. "On a related note, he was also unfamiliar with fossil fuels."
"Not knowing about fossil fuels isn't that unusual. We didn't use them much a thousand years ago," said Starlight.
"It's more than that. He had never heard of anything resembling oil or natural gas. Those substances have been known since antiquity, even if their use wasn't widespread," said Maud. "I know a thousand years is a long time, but it isn't that long."
"Maybe he just had no personal encounters with them?" said Twilight. "He lived near a volcano, but he might not have traveled much. Education back then was mostly word-of-mouth."
Maud shook her head. "Rockhoof had never heard of a tar pit before. There are tar pits near where he lives that are millions of years old. And being one of the original Pillar Bearers, Rockhoof traveled all over Equestria. There's no chance he wasn't aware of them."
"What do you think this means?" asked Starlight.
"I don't know. But I don't think he's lying," said Maud.
Twilight nodded. "I agree. He bears the Pillar corresponding to Applejack's Element, so I can't imagine him being dishonest. Any other ideas?"
"At first I thought he was missing memories. Rockhoof says that Star Swirl the Bearded is missing most of his memories after spending so much time in Limbo, but he didn't seem to think any of the other ancient Bearers had been affected," said Maud. "Star Swirl's missing memories are event-related, meaning things that happened to him. Rockhoof is only missing fact-related memories."
"Episodic and semantic memory," corrected Twilight. "Those kinds of memories are distinct, both in how they are encoded and in how they react with magic—not to mention how likely they are to be affected by physical brain trauma. It doesn't make sense that Limbo would affect two individuals that differently."
"Especially since the memory loss is so selective in Rockhoof," said Starlight. "He really doesn't sound like somepony suffering from retrograde amnesia."
"I'm a little concerned about Star Swirl's memory loss, but that's a separate issue," added Twilight. "Either way, I'm wary to talk to him since I know he's one of the Twelve now."
"The Twelve?" asked Maud.
"One of the details Twilight skipped. It implies he's very old," said Starlight. "I'll get you a copy of Twilight's latest report once she finishes it."
"So far we know the Twelve include Princess Celestia, Princess Luna, Star Swirl the Bearded, Discord, somepony called Theia who used to exist, Lord Tirek, and somepony called Harmony who apparently is part of the Cutie Map now—probably part of the Tree itself," said Twilight. "That's about all we know so far. Oh, and Tirek implied that many if not most ponies are 'on Theia', whatever that means."
"We really need to talk to Discord," said Starlight. "He's quirky, but I'm sure he'll be more forthcoming than Tirek."
"It's useless to call out for Discord unless I know he's listening," said Twilight, "in which case he'd be showing up right now anyway."
All three ponies waited through a pregnant pause.
"I guess he isn't listening," said Maud. "Where does he live?"
"In the middle of Chaos," said Twilight. "But he might not be home, and it would be rude to show up unannounced. The right approach would be to ask Fluttershy to contact him, or send him a letter."
"Well, there's plenty to do in the interim. Thanks for your work, Maud," said Starlight.
Maud nodded. "No problem. I may go talk to Rockhoof again later, but I'll wait to see what you learn first."
"Sounds good," said Twilight. Then she stood up and turned to her former protege. "Manamomonometer time?"
Starlight stood up and grinned. "Manamomonometer time. But where should we go that's isolated enough?"
"I have just the place," said Maud.
"I don't want to damage any part of Equestria, but if we're going to cause damage it might as well be to the edge of Ghastly Gorge," said Twilight Sparkle.
"Ghastly Gorge is already dangerous," said Maud, pointing to a quarray eel peeking out of a hole in the distance. "Maybe you should limit your tests."
"I don't think the tests will be dangerous," said Starlight. "In the worst case, the mana field here will be temporarily inaccessible. We wouldn't be able to cast spells in this area for a short time."
Twilight pulled the device out of her saddlebags, into which it had barely fit. It resembled a spring scale with no hanging hook. She rested it on a rock.
"How does it work?" asked Maud.
"Supposedly, we twist this knob on the side, and it will siphon mana into it. That will send this rod out the bottom, and the mark on the inside will point to the mana level of the area."
Twilight cleared her throat. "Here goes everything," she said, then twisted the knob.
Nothing happened.
"This isn't as exciting as I'd imagined," said Maud.
"Well, that's definitely how it should work. Wait," said Starlight, and she levitated the device briefly with her magic. "There's obviously mana here. It's just sitting there at zero."
Twilight took the device into her hooves and tugged on the rod. "It feels like it's on a spring, which makes sense, but it isn't reacting." She sighed. "Maybe it's so old it's broken. We might need to take it apart to find out how it works. I can't understand why there aren't diagrams of this in historical records."
Starlight Glimmer narrowed her eyes. "Twilight, where's the mana crystal?" she asked.
Twilight inspected the device. "I'm not sure. It must be hidden within the housing or on the back side of the rod."
"The rod twists freely. It would have to be hidden inside the device," said Starlight. "I think we should X-ray this thing."
"It'd be a good first step," said Twilight, switching the device 'off'. "Why don't you go do that. I have some research to do in the library."
Spike met Twilight at the door to the castle. "Twilight! You need to see this," he said. Twilight quickly entered and set her saddlebags down, and Spike led her into the throne room.
Quifons was visible. Trixie's anti-magic cloak had been removed from it and was resting on Fluttershy's throne.
"Spike! I told you to keep that hidden," said Twilight, shielding her eyes. "Wait, why aren't you transfixed by it?"
"Oh, that. I decided to test how powerful it was. I stared at Quifons for a few minutes, and I got used to it," he said. "It's still pretty, but it's not overwhelming."
"Interesting," said Twilight, removing her hoof and staring at the hologram of the sparkly mist. "I must have partially habituated to it after my initial vision. Starlight couldn't look away, but I can manage to do it with effort. Either way, it's distracting. We should cover it up."
"No, wait!" said Spike. "That's what I wanted to show you. Look at this." Spike pointed to a shimmering line that ran most of the length of the map extension's inside rim.
"Huh? Oh, now this is interesting. It looks like the discoloration we manipulated to open the Map's missing wings," said Twilight.
"Exactly. I was hoping you could test it," said Spike. "One side has a bright dot on it, see?"
"Like a sliding marker." Twilight grabbed the dot with her magic and pulled it slowly across the inside rim of the wing, and the map on the table began to change. The first thing Twilight noticed was the disappearance of Appleloosa and Our Town. Then Ponyville began to shrink. Twilight moved the slider faster, and Ponyville disappeared. Canterlot began to shrink, and the Everfree began to grow. Then Canterlot disappeared, and a city appeared in the middle of the Everfree around the freshly restored Castle of the Two Sisters.
"It's going backwards in time," said Twilight. "The Cutie Map lets us look into the past! This is amazing!"
"What's that?" said Spike, pointing to the inner rim of the Tartarus wing. A similar, smaller slider had appeared.
Twilight moved the Quifons slider back and forth a little, watching the slider on Tartarus grow and shrink respectively. "It seems to appear when I start moving the Map backwards through time," said Twilight. She released the Quifons slider and it snapped back to the present. "It won't let me hold both at the same time. I guess I need another mage if I want to manipulate both of them, but the sliders are easier to activate than the wings. Any unicorn should be able to do it."
"Aren't you going to—" said Spike, but Twilight had already grabbed the time slider again and started moving it backwards. Halfway through the slider the Tartarus slider had expanded to full length, and began to contract again.
"Everything is blurry," said Twilight, motioning to the map. "It seems that this middle portion of the slider is moving through time millions of times faster. There aren't any people back this far, though, so there are no civilizations to examine." The land masses shifted and changed repeatedly, with mountains rising and falling. Eventually all the green disappeared, leaving behind a mass of brown and blue. Then the blue dried up, leaving nothing but bumpy brown terrain. Near the end of the slider, the brown turned orange, then became a field of lava, as did Tartarus. Finally, at the very end of the slider, the Tartarus slider disappeared again, and everything became Quifons—also including Tartarus.
"Wow," said Spike. "Everything used to be Quifons? And then it was lava, or something?"
"Apparently," said Twilight. "I have no idea why. Geology suggests that all rocks used to be molten at some point, but we didn't know if it was cyclic or if the world itself was lava. I guess now we know, assuming we trust the Map."
"I wonder where all the water came from, then," said Spike.
"Spike, this is an amazing tool for researching history. It may not prove anything by itself, but we can use the Map to give us clues on what geologists and equuiologists should look for. Maud needs to know about this," said Twilight, releasing the slider and allowing the hologram to snap back to the present.
"Yeah, but I think not destroying Quifons is still our main priority," said Spike.
Twilight was busy researching in the library when Fluttershy walked in. "Oh, hello Twilight. Is this a good time?" she asked.
Twilight pulled her nose out of the book she was looking at and stood up. "Yes! I'm interested in what you were able to learn from Meadowbrook."
Fluttershy nodded and took off her saddlebags. "Quite a bit, actually. She certainly has a good array of healing knowledge. But..."
"But?"
"Some of her cures no longer work, even though she swears they used to work wonders. I had to update her on pony physiology. She was still an adherent to the 'four humors' theory of biology," said Fluttershy.
"What kind of cures no longer work?"
"Leeches, humor balancing, and um, er..." said Fluttershy, blushing. "Enema interventions."
Twilight's brow wrinkled. "Those shouldn't have ever worked, Fluttershy. Did you update her on the placebo effect?"
"I did, but it's more than placebo. Meadowbrook kept detailed notes of everypony she treated, the treatments she tried, and the result. She was able to eliminate tumors and cure advanced ailments."
"That's impossible," said Twilight. "There must have been something else going on coincidentally. But she knows they no longer work?"
"Oh, yes. She suspected as much, and I confirmed it for her," said Fluttershy. "Also, there's something else unusual. Twilight, was Equestria ever... 'smaller'?"
"The borders of the nation?"
"No, the physical earth that Equestria is part of."
Twilight shook her head. "No, and I can actually prove it now, assuming the Cutie Map isn't lying. I've seen what Equestria looked like a thousand years ago, not to mention millions of years ago."
"Oh, my. Well, Meadowbrook is convinced that distances are much larger now. Her swamp is three times as far from Canterlot as she remembers it, and it's several times larger, as well. That doesn't seem like something she would be mistaken on."
"Hmm. We know that Star Swirl's memories were affected by Limbo. Maybe it damaged the brains of the Pillar Bearers in a way we don't understand," said Twilight, as Fluttershy's eyes widened. "Did she seem forgetful at all?"
"No, not at all. She's sharp as a tack," said Fluttershy. "Oh, I hope nothing's wrong with her brain."
"This mystery keeps on getting curiouser. Maybe Moondancer can dig up something from the Crystal Kingdom Library," said Twilight. "The books there are old enough that some of these discrepancies should appear, assuming the Pillar Bearers are correct."
"Isn't there a restricted section of the Royal Canterlot Library?" asked Fluttershy. "With old books in it, I mean. I remember you telling us about it."
"There is, but I'm worried that Princess Celestia might find me there. I've considered telling Moondancer how to get in and sending her to look for me, but Celestia's just as suspicious of her now," said Twilight. "As much as I hate to admit it, right now I'm low on options. Could you ask Discord to meet with me?"
Fluttershy smiled. "I already did! We talked on my way back to Ponyville. He wanted me to pass along a message. He'll meet with you tonight in your bedroom at midnight. He also asked that you not tell anypony else in advance of the meeting."
"That's reassuring," said Twilight. "I guess I'll find something to do while I wait for him. I suppose I could use Rarity's help with the Cutie Map, since Starlight went to X-ray the manamomonometer then spend some time with Trixie."
"Spike just told me that Rarity is making a trip to Canterlot to check up on gossip," said Fluttershy. "She wants to find out what Princess Celestia has been up to lately."
Twilight Sparkle sighed. "Well, then I'm fresh out of unicorns. I suppose it will need to wait until tomorrow."
Twilight Sparkle lay in her bed, nervously looking up at the canopy.
"Seven hours until he shows up. What should I do in the meantime?" she said out loud. Turning her head to the side, she saw the potion sitting on her nightstand.
Zecora had cautioned her to limit her use of the potion, but she had so much left to know. The next question she wanted answered was burning in her mind like a dry hay fire.
Sitting up, she poured a slug of the fluid, took a deep breath, and downed it—focusing her thoughts on a single, clear question...
"Who are the Twelve?"