Of the original seven Watchers, only four remained living. With Rarity’s arrival, all four of them had converged on Canterlot: one, unseen, with no stakes in the outcome, had come to watch. One had come in search of power, and one had been led by fate to reunite with one who he had not realized he needed so badly. Only one remained true to her mission.

For her, entry had been easy. Infiltration was her specialty; all she needed to do was to change her form to impersonate a servant girl. None among them questioned her presence, because none had any reason to wonder why a servant was walking hurriedly through the castle.

She knew that Darknight was somewhere in this castle. He had to be- -she knew that he would have at least made it this far. Rarity was just not sure where he would be. Her goal was to find him. She herself was not powerful enough to fight Celestia on her own- -but she also knew that in truth, Darknight was not either. Still, she remained confident that together they would be able to prevail. They would find a way that would allow both of them to depart in peace.

Finding him would be the challenge. Or, rather, the first challenge. Rarity was so engrossed in trying to process the labyrinthine layout of the castle that she crossed a seemingly empty intersection she almost did not notice the violet unicorn walking away from her.

Rarity gasped when she saw Twilight, simply because her presence was so unexpected- -and yet made so much sense. Twilight was wearing an almost absurdly lavish dress over silver armor, the sort of thing that Rarity could almost never have envisioned her in.

Even at a distance, Twilight suddenly stopped. “That magic,” she said, turning slowly. “I’ve felt it before…”

Rarity did not have time to escape, but she did have time to disrobe and shift. When Twilight saw her, her eyes lit up with recognition.

“Starlight!” she cried, rushing toward the familiar short-maned pale violet pony that now stood in front of her. “You came! You actually came!”

Rarity did not break the illusion. She stared blankly, seeming not to recognize Twilight and hoping she had gotten her pupils to look correct enough.

“They said you left,” said Twilight. “But I didn’t believe them. That was just them trying to undermine me. I was the one who did your surgeries, wasn’t I? I know what your brain is capable of.”

“Uhhh,” moaned Rarity, as if trying to form a word.

“There, there. You must just have wondered off. It’s not like you did it voluntarily. But what matters is that you came back, and just in time for my coronation!”

Rarity stared blankly, but inside she knew that something was horribly wrong. Twilight had betrayed them, and the situation had gotten much more dangerous. Twilight was not a match for Celestia, but she was a lethal necromancer. Fighting her would be more dangerous than either of the Princesses.

Even worse, though, was the strange feeling that Rarity got from Twilight. Something was wrong with her, and it felt as though an evil force were resonating from her body. Her eyes were flitting around quickly, and she swayed as she stood. Rarity realized that this negative energy was emanating from the scars and tattoos now visible on her hoof. Although she could not risk looking at it directly, she found herself not wanting to- -as though the marks might look back into her.

“Come on!” said Twilight. “This is going to be the BEST day EVER!” She giggled with odd giddiness. “First I’m going to be coronated, then I’m going to declare myself the heir to House Twilight! I’ll be a Princess, AND I’ll finally have what’s rightfully mine, for all eternity! My spell is complete, and Shining Armor is finally dead…that little bitch.”

Rarity gasped, but Twilight did not seem to notice.

“And now that you’re here, I guess that means there are only two living Watchers left.” She paused, considering as she rubbed a silver-clad hoof against her chin. “Hunting them down will probably be challenging. I’m reasonably sure that Darknight was killed at the Gala, but Rarity will be hard to find.” She shrugged. “Not that it matters. She’s useless anyway. She’ll probably be purged with the rest of the canon ponies.” She looked over her shoulder. “But you can stay! You’re already basically dead anyway! I’m sure Celestia will let me keep you around. After all, we have so many more experiments to do.” She leaned in close. “In fact, there is time before the ceremony. Perhaps I should open you up and check your implants? You should not have been able to wander off like that. I’m so very curious…”

Her magic formed a construct that narrowed into a blade. She pressed it against Rarity’s forehead next to her horn, and Rarity felt it cutting her. Still, she did not react. She stood without moving or reacting.

“Mage Twilight,” called a voice from down the hallway. Twilight turned to see a guard.

“What?” she shouted, angrily. “Can’t you see I’m busy?”

“The Princess is ready. She has summoned you for your ascension.”

Twilight’s scalpel dissipated, and she leapt forward with unbridled joy before pausing, clearing her throat, and restoring a semblance of professionalism.

“Yes, of course,” she said. “It would not do to keep Celestia waiting. Starlight, come along.”

Rarity obeyed, following Twilight. She felt relieved that her brain was still intact, but only partially. She still had no idea how to stop Twilight, let alone Celestia. All she could do now was wait until a chance arose- -if one even did.

Celestia was waiting on the balcony overlooking the city of Canterlot. In the distance, the ruins and rubble of Discordalot were still burning, and she looked upon this, pleased. She was clad in golden armor, the uniform that she would now wear to signify her eternal strength and dominion over the land.

Twilight entered the room, followed by a group of guards and servants that included one of her own. To Celestia, the mage looked beautiful in her own right. The magic she contained was destroying her, but she carried it with all the poise her position demanded. She was worthy to rule at the side of the Sun, as a replacement to Celestia’s failed sister. Celestia felt her heart beat just a little faster when she saw her. It was the first time in a long time that she had felt exited.

The procession stopped, save for Twilight, who walked forward. From the rear, Rarity watched, unable to intervene. There were to many ponies around her. In order to sneak in, she had left her armor behind, as well as her weapons- -all she had was her magic. There was a chance that she could strike Twilight with a surprise attack, but there was no guarantee that it would succeed- -and every guarantee that Rarity would be slain when her cover was broken.

Twilight bowed to Celestia, and the ceremony began.

“Twilight Sparkle,” said Celestia. “Mage of House Twilight, the last of your bloodline and heir to both the glory and sin of your ancestors. You have come to me to pledge your allegiance to my eternal rule.”

“I have,” said Twilight, her head still lowered.

“And I have accepted you, and your repentance. As these ponies and Equestria herself as my witness, I will take you as my student.”

“And I will stand beside you, my Princess, and shall do everything in my power to assure your eternal rule.”

“Good,” said Celestia, smiling. She lowered her head and tapped her horn on Twilight’s back. “Then I shall grant you what you desire most.”

Celestia raised her head suddenly, and the sun above burst into white hot light. Even Rarity was forced to shield her eyes, although no one noticed her breaking character. They were too focused on protecting themselves from the surge of magical energy.

Celestia rose into the air, her body ablaze with divine energy. Twilight floated upward too, and Rarity could hear that she was screaming. Her scarred hoof reached forward, and the runes glowed, charring themselves into her skin and flesh- -and then burning deeper. With Celestia’s magic, they began to vanish as they were forced inward. The marks on Twilight’s skin left, instead cutting their evil into her soul itself.

Twilight writhed in agony, and then curled inward into a fetal position. There was a plume of silver blood as bones pushed through her back, exiting the rear sleeves of her dress. With a sickening sound of flesh warping and shifting, a pair of skeletal wings emerge. Muscle quickly grew over them, and then nerves and skin, and finally beautiful violet feathers.

Then there was a flash that momentarily blinded Rarity. When her sight returned, she saw Celestia and Twilight drift slowly to the floor. Outside, the sun was orange and dim. When Celestia landed, she nearly collapsed. She was shaking and weak, but she still managed to right herself. Twilight, likewise, stood. She was sweating, but still managed to extend her new wings. She had transcended mortality: Twilight Sparkle was now an alicorn.

Celestia smiled, and she and Twilight turned out toward the view of their kingdom. Celestia lifted a silver crown from a box and placed it on Twilight’s head. “I now pronounce you Princess Twilight Sparkle of Equestria.”

Twilight smiled as the crown was set on her brow, and she looked out with Celestia. As they did, a suddenly flash of blue light passed them. Both Celestia and Twilight’s smiles faded, and looks of confusion crossed their faces. Then, in horror, Rarity watched as their heads slid free of their bodies, dropping to the floor. Their bodies stood for a moment, and then tilted and fell lifelessly in opposite direction, both spilling jets of golden blood as their hearts beat for the last time.

Rarity turned her head toward the source of the spell, and saw Luna standing at the far side of the room, the magic charge from her horn fading as she looked upon her deceased sister. Darknight stood beside her, watching on emotionlessly.

“You do not need to maintain that disguise, Rarity,” said Luna after a moment. “I know who you are.”

Rarity did not react at first, but then allowed herself to return to her normal self. One of the guards- -the only one who was a canon pony- -saw this, and it broke him free of the trance of disbelief at seeing his Princess murdered. He turned to Rarity, only to have a hole appear in his chest, put there by Darknight’s magic. His eyes widened, and he fell. The white noncan guards did not react whatsoever. They only watched on disinterestedly.

“You…you killed them,” said Rarity, looking up at Luna.

Luna nodded. “I needed to wait until she was weak enough. Creating apotheosis drained her of power.”

“But- -but you can’t- -”

Luna looked up, her eyes cold. Rarity immediately fell silent. “She was right, you know. About me being responsible for Discord’s victory. Discord did not escape the Elements of Harmony by some intrinsic element of his being, or from his own magical power. They never fired. And it was my fault.” She stared at Rarity, and her pupils narrowed into vertical slits. “Because I was holding the Element of Loyalty.”

Her body changed. The black stain on her flank grew and expanded, spreading from her cutie mark to cover the rest of her. Her blue mane extended and lost form, becoming a swirling mass of starry energy. As her body became midnight-black, armor sprang up from her skin, its glowing silver conjured of pure magic. Watching her, Rarity felt the same coldness she had felt when Darknight had turned.

The pony that stood before her was no longer Luna. She was something else. Taller, more slender, and with no semblance of pity in her eyes. Rarity turned to Darknight, and he looked back at her. He could barely meet her eyes, but he forced himself to do so. Then the blackness covered him too. He did not attempt to resist, and within seconds it had consumed him entirely. He stood beside the pony that had been Luna as a miniature unicorn version of her.

“Darknight…”

“His name is Night. And he will rule at my side.”

“And who are you, then? You are certainly not Luna. Not anymore.”

The alicorn smiled, showing her pointed teeth. “No. Luna died centuries ago. I am Nightmare Moon.”

Nightmare Moon walked to the edge of the balcony where her sister’s head lay, and raised her hoof. Rarity winced and closed her eyes as Nightmare Moon brought it down, crushing it with a horrid sound like a ripe fruit bursting open and ensuring that she could never again be resurrected. “And I am now the one true ruler of Equestria.”

She raised her horn to the sky, and it glowed with black energy. The sun dimmed, and then grew brilliant- -but not with a warm yellow glow. Instead, it became silver and dim. Rarity felt its light, but she felt no warmth. If anything, its glow made her feel profoundly cold. Outside, the blue sky faded into darkness that the new moon could not light. Stars appeared in the sky, more beautiful than any that had been seen since the dawn of Equestria.

“And my night shall last forever,” said Nightmare Moon as she looked over the world.

“Do you have any idea what you have done?” asked Rarity.

“Yes. I have done what I have dreamed about for one thousand years. I have superseded my sister. She was a monster, not worthy of their love. But now they will appreciate what I have done for them. They will love me instead.”

“The noncans- -”

“The noncans hold no loyalty to Celestia. They only seek one who will respect them as ponies. And I will. Not every decision my sister made was a poor one.” She took several steps toward Rarity, the metal of her shoes clicking on the floor. Rarity raised her horn, charging it in one last desperate attempt at defense.

“Don’t,” said Darknight. “There is no point in resisting this, Rarity. This was the only way that Equestria could survive. That we could have peace.”

“It’s not you saying that, it’s her!” cried Rarity. “Darknight, she is controlling you!”

“My name is Night,” he said. “And she is not controlling me. There is no need to. Celestia would have burned this world, but without a ruler Equestria would be left in shambles.”

“He came to me of his own free will,” said Nightmare Moon. “It was his decision and his alone to share my power. To take his rightful place as my son. And many more of his kind will come to me, to rule this world as my children.” She turned to Rarity. “But that means that you too must make a decision.”

“What kind of decision?”

“You showed me kindness when no others would. You treated me with respect, even when I was weak and powerless, and without expecting anything in return. You were my friend when no other pony would be. And I wish to repay you in kind.”

“And what, exactly, do you mean by that?”

“I mean that you will have a place here, with me. At my side. I cannot rule alone. I need those I trust with me. I already have Night,” she gestured toward the black unicorn on the far side of the room, “but I want you too. A pony who like him will never age or die, but will stay with me forever. So I don’t need to be alone again. You will be given wealth and power if that is what you want.”

“Why would I want any of those things?”

“Why indeed.” Nightmare Moon pointed toward Twilight’s body. “That was her undoing. A blind lust for something she could scarcely comprehend. But you are different. Position, then? And not just for you. I will send for your daughter.”

“Sweetie Belle?”

“She will be safe, and given a life worthy of the daughter of my viceroy. Education. Safety. Whatever she needs. And she will be with you, as she ought to be.”

Rarity looked at Nightmare Moon, and then at Night. “There has to be a catch,” she said, turning back to the black alicorn.

“There is. Because my rule will have a cost. Not to you, but Equestria.” She looked out the window. “Do you feel it? Eternal night will have consequences. The planet is already cooling. It will progress into a new ice age. Famine will be rampant, and many ponies will freeze to death beneath a beautiful sky.” She turned back to Rarity. “I estimate that ninety percent will die in the first year alone. Only the strongest will survive. Canon, noncannon, whoever they may be. Those worthy to be my subjects.”

“That is horrible!”

“It can’t be helped!” snapped Nightmare Moon. “There is no other way!” She took a deep breath and calmed herself. “Which is your decision. If you still wish to save Equestria, this is your chance. To challenge me. To challenge US.” She gestured to Night. “And to die here and now.”

“So to take everything I’ve ever wanted,” said Rarity, “or to die for what’s right.” She chuckled softly. “I must say, that is one hell of a choice.”

“Make it carefully.”

Rarity paused for a long time, considering deeply. Time seemed to pass slowly as she thought, and as Nightmare Moon and the pony that had once been Darknight waited for her response.

Then Rarity lifted her head, and made her choice.