Now on her knees, Sunset Shimmer gritted her teeth against the pain. The plasma interference from her discharge cleared, and much to her dismay, Celestia still stood. The Harmony had sacrificed itself to block the beam.

“To early,” she muttered. “To early, not powerful enough.” Then she laughed and stood, willing the pain away. She looked down at Xyuka, who for the first time since Sunset had known her appeared at least vaguely concerned. “No matter. I’ll just fire it again. And this time- -”

She suddenly stopped and doubled over, grabbing her torso. Something was horribly, horribly wrong. Her avatar was in profound pain, and she tried to find a reason- -until she realized that it was not the avatar that was in agony.

Sunset screamed as the inner walls of the Crimson Horizon burst open, tearing themselves apart from within. The organic, brown, bark-like surface was torn away, revealing the linear white-silver metal beneath, the geometric channels of its circuitry pulling massive energy back into Sunset Shimmer’s central Core. She tried to run diagnostics to understand, but none of it made sense. It was as if hundreds of millions of systems that she had no conception or recollection of had just simultaneously activated.

The energy backfed into her Core, and the central room suddenly filled with orange-violet energy. Her drones were vaporized by the explosion of force, and her avatars liquefied, their connections failing. Only the avatar connected to the Core directly survived, as did Xyuka and her associates.

That was when Sunset Shimmer saw the look on Xyuka’s face. The armored Pegasus was not concerned, or indifferent- -she was smiling. Not a fake smile; the most horrifyingly genuine one that Sunset had ever seen.

Sunset fell to her knees, doubling over in pain.

“Excellent,” said Xyuka. “I was momentarily concerned that the premature firing would not provide enough energy to initiate the reaction. It appears, however, that it was more than adequate.”

“Xyuka!” wheezed Sunset through her pain. “Please- -help me!”

“Help you? Do what, exactly? You are serving the very purpose you were constructed for.”

“What- -what are you talking about?” asked Scootaloo. “Xyuka, what did you do?”

Xyuka turned toward the younger version of herself. “I will have to admit, I have not been entirely honest with you, Scootaloo.”

“Xyuka!” cried Sunset Shimmer, raging against her pain. “You betrayed me! You- -after everything I did for you! After I found you in the Void, after I saved you, you repay me like this- -”

“No,” said Xyuka, her quiet retort silencing Sunset instantly. “I’m afraid that is the primary element of the lie. I was never trapped in the Void, Soy-Chet. I was not lost. I was waiting. I had indeed reached an entropy barrier- -but I still had access to several universes. I was simply collecting parts to get to the next grouping…and imagine my luck when a damaged Equestrian starship and most of a planet ended up in my possession.”

“You’re lying- -you have to be- -”

“I’m not. Sunset Shimmer, you were already dead. You did not heal me. I rebuilt YOU. I optimized your genetics, cybernetics, the ship, the drones- -I built it all. Then I implanted an ideology into your mind. One you would never question. One that would force you to end up here, and now.”

“No! I- -I remember! I chose to become a Core! I- -I made this! I- -”

“You don’t have any memories,” said Xyuka, as if talking to a child. “Not real ones, anyway. Yes, you did choose to become a Core. But have you ever actually tried to think? To remember what you were? Do you remember your childhood? Beyond the landscape, the town. Your best friends? Your first kiss? What your parents looked like? If you even had siblings?”

Sunset started to answer that of course she did- -but then her eyes widened as she realized to her horror that she could not recall any of the things Xyuka was mentioning. She remembered being a filly, but it was like a fact in her head, like how she had known that Starswirl’s machine was located on Earth. It was just a piece of cold, empty information.

“Now you understand,” said Xyuka. “Your mind? I built it. From creative whim, or even partly from my own memories. You are nothing but a construct, a machine. You always have been. And I have always been the one in control.”

“But- -but why? Xyuka, why? I don’t understand! I- -I can still feel it! To destroy Equestria- -”

“Equestria is meaningless,” said Xyuka, coldly. “Your only purpose was to assemble the Crimson Horizon, the Crucible, and the Gate in one place. To fire the weapon. If Twilight had not intervened, yes. You would have destroyed Equestria. But killed yourself in the process. Dying as you are now.”

“You sick bastard,” said Scootaloo. “You- -you destroyed an entire planet! Millions of lives- -and you would have taken out all of Equestria too? Just- -just like that?”

“Scootaloo, you couldn’t possibly understand. All the people I kill? In another reality, they’re all alive. All fine. Death has no meaning on a multiverse scale. Do you know how many times I’ve done this? How many times I’ve been forced to strangle a Sweetie Belle, to feel her body go limp under my grasp? Or to hear Applebloom’s screams of terror and betrayal as I’ve incinerated her land and family? Or watch the life drain out of a Rainbow Dash’s eyes by my own hoof? And yet there are infinitely more Sweetie Belles, Appleblooms, infinitely more Rainbow Dashs. So many more.”

“But- -but WHY?!”

“To get back. I have to get back. To my own friends. To my own world. I didn’t lie about that part, Scootaloo.” She turned to Sunset Shimmer, who was now lying on her side in a fetal position, her cables beginning to overheat and melt as her true body began to liquefy from the excessive energy it had absorbed. “Which was the point of this. To overcome my entropy limit. To propel me into a higher universe. To let me take one more step in my journey home.”

Sunset Shimmer looked up at Xyuka. She was weeping. “None- -none of it was real,” she said. “Please…there has to be another way. If I…if I could just do it again. I never even had a chance to have a friend!”

Xyuka stared down at the dying Core. “Life does not give second chances. There is no forgiveness. You chose this path yourself.”

“But…did I really have a choice?”

“No. Of course not. Because I designed you not to.”

Sunset Shimmer looked up, her eyes so wide and pitiful that Scootaloo was forced to look away. She opened her mouth, and all that came out was a squeak as she expired, her body liquefying on the floor. Above, her true self groaned in agony as it slowly imploded, creating an extradimensional vortex in its wake, a brilliant orb of white light hovering in the center of Xyuka’s machine.

Xyuka raied her hoof and projected another pair of Voqutan portals. “Go,” she instructed Scootaloo. “Take Trixie. Keep her safe. The translocation process is…abrasive. I don’t think you’d be a fan.”

Scootaloo paused, not even moving toward the portal. “What happened to you?” she said. She did not sound angry, just profoundly disappointed.

“What happened? I lived too long,” said Xyuka. “Far too long. Like I said: every new experience, it takes something away from you. I’m not a pony. Not anymore.”

“Bullshit,” said Scootaloo. “It’s just bullshit. You were me once. Do you even remember that?”

“I was never you…but yes. Sometimes…” Xyuka closed her eyes. “Sometimes I remember what might have been…”

“I’m going to make you a promise,” said Scootaloo, hefting Trixie’s still unconscious body and stepping toward the portal. “Even though you don’t deserve it. I’m never going to become like you, like the…the thing that you became.”

Xyuka turned, and looked her alternate self in the eye. “I will pray to every god I have not yet slain that you do not, Scootaloo.”

Scootaloo stared at her for a moment, and then stepped through the portal. It closed, and once again Xyuka was alone. She stared at the spot Scootaloo had been for a long moment, and found herself wishing it could have been different.

Then she turned back to the vortex. She raised a hoof to her face, and part of her armor liquefied, expanding and rebuilding itself, covering her face with a new mask. It sealed around her head just as the vortex began to peel her body apart.

“Don’t worry,” she said, addressing the portal and ignoring the pain. She smiled. “Don’t worry…I’m coming home. I’ll get back. We’ll be together again…someday.”

Then the assembly closed. Starswirl’s Gate, the Crucible, and the Crimson Horizon were pulled together. Xyuka- -Scootaloo- -stood in the center as her machine executed its function flawlessly. It imploded, vanishing from the universe and dragging her with it to the next one, leaving not a trace behind as she departed.

And then, like that, it was over.