The math wasn't hard. It didn't take us long to reach consensus.
"It looks like we can only get it to work if we're able to increase the time duration between successive attempts," I said. "Maybe we could send messages back in time to coordinate with the other universes."
Twilight shook her head. "There's no way to guarantee it would be done properly, since the universe we send the message to is already a statistical aberration," she said. "But I'm still optimistic. There's probably a clever way around this, and even if there isn't, there should be ways to benefit from time travel of the third kind without creating any bad universes in the process. We'd just have to abuse it the same way we can abuse time travel of the first kind: plan something beneficial that already meshes with existing data about the past."
"I hate to be negative, but we've already created bad universes," I pointed out. "Consider the world the dead Moondancer came from. She must have come from a world where somepony—probably Starlight Glimmer—opened the door and found nopony in the chamber. If that's the only difference between our worlds, why would I have gone back in time initially?"
"I don't know," said Twilight, rubbing her temple with a hoof. "Just because our theory is deterministic doesn't mean it isn't impossibly chaotic and unpredictable. If your other body hadn't been there on the floor, you probably wouldn't have cast this spell on me. Then we probably wouldn't have come up with this theory yet. All sorts of things would be totally different by now, and it hasn't even been a full day since we broke that particular symmetry."
"Ugh, back to square one," I groaned. "Honestly, though, I'm more concerned about the fact that I was killed at all. There was no blood trail, so I must have died in the lab, which means the killer had access to our lab and almost certainly opened the door I arrived in."
"Then it must be Starlight Glimmer, or else somepony who we allowed access to the lab," said Twilight. "I can't think of a scenario where you or I would have killed a Moondancer, even though there are no doubt an infinite number of plausible situations in which either of us would do so without hesitation. It seems far more likely that Starlight managed to break in somehow. It would be easy enough for her to do, of course. She could break in at any point in the future, then use our failsafe chamber to go back to last night."
"Oh, that's right! If we hadn't found my body, we wouldn't be eager to shut down the lab," I said. "In the world my dead self came from, Starlight would have had plenty of time to break into the lab. Her travel time would only be limited by how long she could feed and hydrate herself to stay in a chamber without using magic."
"And go to the bathroom," said Twilight.
"Ew," I said.
"This is good news, though. It means we have the upper hoof, and should be able to stop her this time. All we need to do is turn off the power to the lab for a few minutes. That will sever her ability to travel from any point in the future backwards over that particular moment, since the fields need to be running constantly to allow regressive time travel," said Twilight. "We don't need the failsafe of chamber three anymore, and it wouldn't make sense to use it for anything anyway, since it goes to a different universe. We don't want to affect other universes any more than absolutely necessary. One dead Moondancer is more than enough fatalities in any number of universes."
I shrugged. "Well, we have plenty more than that," I said.
"What do you mean?" said Twilight.
"It's like I said, we've created bad universes already. For starters, there's a universe out there where I wasn't able to save your life. You had to go back in time to warn me, and the first time if nothing came out of the chamber, that Twilight would have died, so I would have been the one to travel back in time. There would be several different iterations. At some point I probably died, too, because we wouldn't want to switch from me to you making the trip—that would leave a universe with two Moondancers and no Twilights."
"Is that a certainty?" asked Twilight. She looked very odd with her brow furrowed in thought but the muscles in her muzzle completely relaxed.
Then I noticed something else which brought back a recent memory. Twilight definitely looked healthier than Starlight Glimmer's impression of Twilight had. Both times I'd spoken with Starlight, when she made her wings disappear, I could see the outer edges of her ribcage. She was unusually thin, almost anemic. Maybe she was just a thin mare? But everything else looked exactly like Twilight, so it seemed odd her illusion spell wouldn't have covered that as well. Maybe Starlight had been reflected for a while while maintaining the illusion, and she simply had nothing safe available to eat, so her illusionary body also appeared unhealthy. I had no way of knowing, since I didn't have a clue what normal-parity Starlight looked like.
I wanted to tell Twilight about my two encounters with Starlight Glimmer so she could help me theorize, but I was still afraid to do it while she had the robotic—
"Moondancer?"
I snapped back to attention. "Sorry, got distracted. Yes, multiple dead Twilights and Moondancers are already a certainty. It's not perfectly symmetrical time travel, as we've established. As you go forward through the loops, or backwards for that matter, the more universes you cycle through, the closer the probability of failure approaches one," I pointed out. "That means there are at least two Equestrias with a dead Twilight Sparkle, not to mention one or two with a dead Moondancer."
Twilight froze, and stared off into space. "No. This situation is completely unacceptable. All the ponies in those two Equestrias are likely doomed without access to the Princess of Friendship. And it's probably more than two Equestrias, because of the exponential growth in universe creation. It could be anything short of infinite."
"I don't like it either, but what can we do? I mean, you've already seen me die once from these shenanigans."
"You're less important," said Twilight Sparkle, without a hint of emotion in her robotic voice. It stung painfully, and I struggled to avoid crying, because I knew deep down it was true. "My personal hoofprint is too important to our universe. That was the lesson I learned from my encounter with Starlight Glimmer—my destiny is extremely critical to the future of Equestria. The potential for free energy isn't worth countless doomed Equestrias."
"It is what it is," I said softly, looking away from my emotionless 'friend'. "We know this can't be time travel of the first form, because the antimatter path is invisible. The idea Starlight could have been making the antimatter invisible doesn't make any sense because she would have no motive to manipulate us into thinking we had invented an advanced form of time travel, even if she really wanted to mess with our minds. It's just too ludicrous."
Having barely held back the flood, I slowly turned my head to look at Twilight again. She was lost in thought.
"Moondancer, what did you discover today, if anything?" she finally asked.
"Hmm? Oh, my research," I said, having to refresh my own memory. "Right. I learned that the parity reversal isn't subatomic, in contrast to our prediction. It's actually at the chemical level, which is consistent with something magic can do, but not what the chambers should be capable of. So the source of the effect is still a mystery," I said. Then I paused for a moment as I decided it was time to come clean. "Look, Twilight, something happened just before you showed up, which I probably should—"
Twilight abruptly stood up and walked to the door, without looking back at me. "I need time to postulate," she interrupted, and she left the building before I could even think to react.
I resolved to work on a counterspell for that stupid emotion magic. Twilight was starting to act scary, and I had a bad feeling in the pit of my stomach.
She didn't return in a few hours, so I went to bed.
I woke up so groggy I was certain I was coming to in a hospital bed or gurney for the fourth time in as many days. However, I wasn't lying in a bed. I was lying on a cool metal surface, and it was completely dark. I didn't have my sweater on me, and my muzzle reeked of chloroform.
I opened my eyes wider, still seeing nothing, but I felt fabric against my eyelashes. I realized I was blindfolded. I tried to stretch, but my limbs were bound to my barrel with what felt like rope. I squirmed enough that my rear hooves were able to touch one wall as my muzzle bumped another wall.
Sheer terror filled my barrel. There was only one way the room could be this small. I was in an antimatter chamber, and it was probably on. In all likelihood, I was traveling backwards through time.
"Shit shit shit!" I said, trying to roll over. Something held me in place, however. There was a weight on my back, like two hooves pressing down. I didn't have the leverage to push back against them.
I stopped moving for a moment, and desperately tried to remember what had happened. I couldn't recall anything after falling asleep last night. I must have been abducted in the middle of the night, then transported to the lab. Could Starlight have gotten away with something that bold? Maybe if the guard thought she was Princess Twilight Sparkle.
However, that made even less sense. Starlight was trying to convince me to get away from the lab, so she'd be the last pony I'd expect to knock me out and bring me here. Unless, of course, it was a different Starlight Glimmer. Multiple universes prevented me from taking even the most ridiculous options off of the table.
Theorizing was useless, but I did have the ability to speak. "Let me go, please!" I cried out. Immediately, I felt like a coward, but my mouth wasn't connected to my conscious mind. I was operating on pure instinct, and instinct said 'beg'.
I heard a sigh from above me. It was followed by a strange vibrating noise like a soft jackhammer, then a distinct 'click' sound of the door unlocking.
Then my senses started going crazy. I was still alive and conscious, but extremely disoriented. I couldn't tell if I were breathing out, or in, or both at the same time. The pressure on my back disappeared, but suddenly the air pressure everywhere around me began to swell. I tried to roll over, but squirming felt like I was immersed in gelatin. Something pressed against me, like another body, then somehow it pressed into me, everywhere at once.
Then the same thing happened in reverse: I separated from a Moondancer-shaped lump as I rolled over and over. It felt vaguely like I had been kicked. There was a lurching sensation, and warm wind rushing over me as the pressure dropped. It felt like I was rolling in two directions at once, and if I hadn't known better I would have sworn I'd ended up right back inside the chamber where this had started.
I heard a door shut, and somepony ripped off the blindfold. Now I was staring up at my good friend Twilight. It was clear from her lack of disorientation that she hadn't been the one in the chamber with me. I felt a great sense of relief, but adrenaline still surged through my veins.
"Moondancer, are you alright?" she asked as she removed my bindings. I stood up on three shaky legs and one rolling cast, and kicked the cursed rope away from me. Looking around, I noticed the anteroom looked normal, with a few minor exceptions. There was no blood on the floor, even though the club was lying here, so I assumed Twilight had cleaned it up. The only true oddity was that the bathroom door was now located on the opposite side of the room.
"Thank Celestia," I said, breathing a tremendous sigh of relief. "I was petrified that Starlight Glimmer was going to be on the other side of the door! Wait, this is the past. You haven't formulated the theory on how the chambers work yet."
Twilight shook her head. "No, I have. I traveled into the past in order to meet you here after you got kicked out of the chamber," she said. I stared at her and began to feel concerned. Twilight looked gaunt, as though she hadn't eaten in several days. I realized that she wasn't flipped to her false (mirror) image: the stripe was on the correct side of her mane. But that was from my point of view, so it was clear we were both parity-reversed, which matched her story.
Then I had a terrible thought. I wondered, if Twilight tied her forelock up like mine, whether or not I'd notice if the stripe were on the wrong side. I wasn't sure.
"How long have you been reversed?" I asked. "Twilight, you need to drop that bucking spell and tell me what's going on."
Twilight's face remained vacant of emotion, but a tear trickled from the inside corner of one eye down her cheek. "This is very hard for me, Moondancer."
"Wait, the spell is down? But you still look and sound like a zombie!" I said, grabbing her by the shoulders.
"The spell isn't down. It's just imperfect, and the magic is being pushed to its limits right now," she said calmly. "Moondancer, you once told me if I had to choose between you and Equestria—"
"You should choose Equestria, and yes, that still applies," I said. I put my hooves back on the floor. There was a slight rattling sound. Both of my forehooves were jittering in place against the metal.
Then Twilight stepped forward and kissed me right on the mouth. It was soft, but hollow, without any feeling. As she leaned back, my jaw hung open.
"My second kiss," I said, stunned. "But you'll remember this one, at least, right?"
Twilight nodded. "Of course. But I now suspect this one was my first, in both senses of the word," she revealed. "I'm so sorry, Moondancer."
I noticed Twilight's horn glowing, and I didn't see the club on the grou