Infinite possibility flashed in Twilight’s mind as she held the theory cube in her magic. Ideas beyond number or understanding assaulted her mind’s eye in an unending battery of data and theory. The complexity of each fragment boggled her mind, each too intricate for Twilight to even begin to comprehend before the next appeared. She furrowed her brow against the sensory overload and attempted the magical equivalent of Applejack’s classic apple-in-the-mouth technique.
A little better.
A few more tries at stemming the tide of information and life became eminently more livable in Twilight’s brain, but more interesting still, the previously-disorganized cascade of thought had coalesced into a single nexus of sound.
No, not just sound. A voice.
“Hello, Twilight.” the voice said dryly. “I see you finally figured out just what was in that cube I gave you.”
“Sparkle?” Twilight said aloud. Sunset looked over at her, confused.
“X-37-B. The very same,” the voice came back. “And you don’t need to speak with your mouth for us to communicate. Skies above, you two really are fresh meat.”
“I thought you said this cube contained your complete multiversal theories?” Twilight said. “Why do I have your voice in my head?”
“Well, you didn’t exactly give me much time to come up with a reference,” Sparkle replied cooly. “So I made the next best thing: a perfect replica of my consciousness, just waiting for an emulator to run in. Which, surprise! That emulator is your brain. I’m ready to answer any questions you may have.”
Twilight tried to glare at her antagonizer, but found the task a difficult one. “I’ll debate the ethics of perfect cloning with you later,” she said. “For now, I guess we do need your help. I can only assume you’ve met Tirek?”
“Met him! Ha!” Sparkle replied. “I’ve sent too many versions of that loud-mouthed centaur packing to count. Sometimes he’s in awe of Sunset and me, sometimes he thinks he can stand up to us, but he’s hilariously incompetent no matter what conclusions he draws. Is there seriously a Tirek giving you trouble?”
“We accidentally set him loose from Tartarus, and the Accord has ordered—”
“The Accord? Those buffoons? This gets better and better with every moment. I’ve met countless Twilights and Sunsets, but you two do seem to have a special knack for getting tangled up in the most trivial of problems,” Sparkle said, practically cackling.
Twilight frowned, and Sunset, who had been studying her, asked her a question. Twilight didn’t catch it.
“Sunset said they’ve executed countless versions of us,” Twilight retorted.
“Be that as it may, “ Sparkle replied, “they’re no less foolish for trying to regulate a multiverse of literally infinite size and potential. I don’t even remember the last time I saw one of their agents, and I can only assume I’ve broken near every ‘law’ they’ve ever enacted.”
Twilight focused herself and spoke sharply. “Whatever your opinion of the Accord, if Sunset and I can’t beat Tirek and take him to them, they’ll—”
“They’ll what? They’ll kill you? If you don’t beat Tirek, you’re dead anyway. They aren’t going to interfere in your home dimension—too worried about their rules, I’m sure—so it isn’t like anyone you care about is in danger...aside from Sunset, of course. You have all the power in this situation, Twilight. Here, watch this.”
Twilight saw her manifested horn blaze with a thick layer of overglow, and suddenly she and Sunset landed.
Not on any of the orbs floating in the between-space, no. Whatever spell Sparkle had wrought—and with Twilight’s magic, no less, which was more than a little alarming—had plucked the two of them from the stream of light they were travelling in and put them down in the middle of a field of grass.
“Twilight? What’s happening?” Sunset exclaimed.
“I’m—the theory cube—I’m sorry, Sunset, give me a moment,” Twilight said, before turning her focus inward again. Trying to pay attention to the outside world made it hard to keep up all the spells damping the output of the theory cube, let alone converse with Sparkle.
Turning her metaphysical back on her friend, Twilight directed herself at Sparkle once more. “What did you do?” Twilight demanded.
“I’ve disengaged us from the natural forces that pull matter out of the space between dimensions,” Sparkle replied.
“Why? Why in Equestria would you do that?” Twilight said.
“Because you two need time to think, and when you don’t have space, you don’t have time, either,” Sparkle replied. “We can stay here for as long as we like. Not to mention it is very beautiful—and that’s coming from someone who’s seen far more than you could ever imagine right now.”
Twilight considered this. “I suppose that is quite useful, actually, but could you please refrain from using my magic without asking? It feels even more like an invasion of privacy than having you in my head does. And speaking of having you in here, any quick notes on how to make this cube of yours slightly more magically bearable?”
Twilight felt like she could almost see Sparkle smirking. “Permission to use magic? I can tweak your wards for you.”
“Ugh, fine. Granted,” Twilight replied. Her horn glowed again, and suddenly the weight on her conscious was lifted, and she could hear Sunset talking to her. No, shouting to her. No, crying to her.
“Twilight! Twilight, are you okay?” Sunset was saying, her voice awash with worry. Twilight turned to her friend—she realized they were both on the ground—and did the first thing that made sense.
As she broke the kiss—our third! Twilight realized. Our third kiss!—she wrapped Sunset in a tight hug. “I’m so sorry,” she said. “I’ve been trying to figure out the theory cube ever since Sparkle gave it to me, and I guess these powers from the potions Aeon gave us were the last piece.”
Sunset looked at her, and a grin broke out on her face. “Well? What’d you find out?”
Twilight frowned. “Unfortunately, Sparkle took the easy way out when she enchanted the cube. I have her voice in my head now.”
“She’s using telepathy? Across dimensions?” Sunset asked, looking almost impressed.
“Worse,” Twilight said. “It’s a copy of her consciousness. That’s what the magic I used that put us here was. She can apparently access all of my magic, in addition to being an insufferable voice in my head.”
Sunset’s crossed mouth mirrored Twilight’s own. “Well, what does she want?”
“To help.” They both jumped as Sparkle’s voice emanated from nowhere. “Sorry, Twilight, made one additional change. I figured it would be easier if I could talk to Sunset directly.”
“Well, oh, well—what do you mean, help?” Twilight said, her teeth grinding just a touch.
“Don’t do that; tooth regeneration magic is painful,” Sparkle noted. “I mean I know how you’re going to beat Tirek and deal with the Accord while we’re at it. It’s simple, really.”
Sunset smirked at Twilight. “You weren’t kidding when you called her insufferable.”
Twilight smiled back at her.
“The beginning of our relationship is always so cute,” Sparkle said. “Anyway, the plan is this: we banish Tirek to some particularly inhospitable dimension, you two get your hands back on your Talisman—that’s what you’re still calling it, right? So childish— and head back home, and then we make a few simple alterations to the fabric of reality and lock interdimensional travel forever.”
Twilight and Sunset’s eyes bulged. Nearly in unison they cried, “We do what?”
Sparkle sighed, and when she spoke next, she sounded almost wistful. “Sunset and I have had some good times, but I meant what I said to you both. Voyaging breaks your mind. I didn’t even realize just how true that was until I woke up in here with Twilight. I thought I’d burned every last shred of sentimentality out of myself a few hundred years ago, but I should’ve known seeing the world through younger eyes would...well, no matter.”
“But...what about all the Sunsets and Twilights that are still stranded away from their home dimensions?” Sunset asked. “We don’t have the right.”
“I don’t want to become her,” Twilight murmured. Is this what it means to be a god? Not to have powers, but to have the power to make decisions like this? Sunset’s right; there’s no way we can decide the fates of so many of ourselves, not to mention anypony else who’s away from home.
But at the same time, if the multiverse really is infinite, doesn’t that mean we’re also stopping an infinity of suffering by preventing travel by other monsters like Tirek?
“Trying to do the math on the ethics won’t help you now, Twilight,” Sparkle said. “Trust me. This is what we have to do. The prime version of us will probably figure that out in a few hundred more years anyway, and it won’t matter in the slightest what you do now. We weren’t meant to Voyage.
“Let’s end this now.”