The moon shimmered softly in the night sky, placed precisely in the right spot on a velvet canvas dotted with jewels. It was beautiful… but not as beautiful as it could have been. It lacked a certain… something. A certain presence. A presence that the white alicorn who stared regretfully up at it could never hope to project for the night sky should have been Luna's and Luna's alone.
Tonight, though, something was different. A sense of anticipation was almost palpable in the air. The outline of a mare's head was visible on that moon. It was a night Celestia both waited for… and dreaded. It was night she would have to face her sister again, and if she could not convince Luna to come back to her… Twilight will have to banish her again. There is no choice. I cannot allow her to destroy all of Equestria, no matter who she is. No matter who she was. She had seen it happen. Seen Luna be rejected, seen her anger grow, heard the hurt in Luna's voice… and there had been nothing she could do. She could try to comfort her sister, but Luna wasn't happy with just that. YOU SAY YOU AGREE WITH ME, YOU CLAIM TO UNDERSTAND - SO WHY DON'T YOU DO SOMETHING? TELL THEM TO STAY AWAKE FOR MY NIGHT - YOU COULD DO THAT, AND THEY'D OBEY YOU. THEY WORSHIP YOU! THEY'VE NEVER WORSHIPPED ME! Luna's accusing words rang in her ears, their rage, their fury, their resentment, and it was all she had been able to do not to go to her throne room right their and then… You cannot compromise your subject's happiness, Luna, for a mere whim. The words had come out harsher than she had intended. Her sister had always been to rash to rule responsibly…. I had to hold her in check. I had to.
Just like you had to send her to the moon? The voice taunted her.
I was wrong. That part of her that was a sister was almost, Celestia thought, hysterical. IT WAS WRONG! But the part of her that was a princess pushed forwards.
To let her run free, turn all of Equestria into a barren wasteland, kill every living organism on the planet out of sentimentality - THAT would have been wrong.
I ignored her wishes. I gave the ponies an extra hour of sun for their crops that winter, knowing how much it hurt her - and I was distant, even together. A ruler cannot be biased, I told myself, but what is ruling worth when you're alone?
Everything.
Nothing.
The lives and happiness of a thousand ponies.
At the cost of your own happiness. At the cost of your sister.
Looking up, Celestia noticed that the outline of an alicorn had disappeared from the moon's surface.
Mother. Father. How did you endure it? Year after year after year… at least you had each other. Because of my own haughtiness, my insistence of putting my responsibilities above everything else, I have no-one now.
Nightmare Moon felt stiff and sore. Her joints ached, every beat of her wings was a trial. A thousand years. A thousand years, sister, because I decided to stand up to you for once. She had broken free from that. She had broken free from everything… almost. Maybe once she finished her sister off she'd stop feeling so bound. The moon stands in nopony's shadow. It is not just a pale reflection of the sun. It has a life of its own. And she had been imprisoned in the moon for a thousand years for daring to think that. That was her sister's 'justice'.
A leathery wing briefly obscured the sky and Celestia rose to her feet. She had come to this meadow alone, knowing that if she had stayed in her palace her royal guards would never let her come face to face with her sister. No. She is Nightmare Moon. I have no sister. If Twilight has to imprison her for another thousand years, I will have to remember that. Celestia wove a shield of light around herself. She could not let herself be defeated without even trying to reason with… with that creature.
"Hello, then. It's been a while." Nightmare Moon chose her words with the intention to hurt and judging by the look on her sister's face, they did. She looked as if she had been stung.
"Feeling a bit guilty? Or just worried about how I'm going to get revenge? You may look regretful now, but you'll REALLY know the meaning of regret once I am done with you. The night will last forever. I have no further use for the sun. Should I lock you away in the sun for a thousand years? How would you like that? But no, giving is always better than getting isn't it, sister?" Even though the only way Nightmare Moon could hurt her through that shield was if Celestia let her through, the white alicorn back away from the force of Nightmare's words.
"Luna. Listen to me. Remember." The use of her former name enraged Nightmare.
"I AM NOT LUNA. I AM NOT YOUR OBEDIENT LITTLE SISTER. I WILL NOT LET YOU OVER SHADOW ME. YOU WILL LEARN TO FEAR THE MISTRESS OF THE NIGHT!"
"Remember. Remember when we laughed at the lamest jokes just for the sheer happiness of being together. Remember when I coaxed you out from beneath your parents wings when you were nervous about publicly raising the moon at the Winter Solstice celebration. Remember." Nightmare edged closer and Celestia let the lightening she struck at her through the shield. The confidence that she would never hit her beloved sister irritated her. Another well-placed hit dissolved the shield.
"Give me one good reason I shouldn't strike you down here and now, burn you crisp in less then a second."
Celestia stood up straight to face her sister. All of her accusations hit the mark, yet the guilt and pain seemed to belong to another pony as she calmly looked Nightmare Moon up and down.
"Kill me then. It's no more then I deserve." Twilight would be devastated. She has no friends, but I am her mentor and almost a second mother to her. She pushed those thoughts away.
"Kill me. But first, remember."
"Remember how I watched you guide the moon and stars for your very first time. Remember how we celebrated and you got ice-cream all over your face. Remember how every night I stayed up stargazing, and every morning you watched me bring the dawn. I treated you badly, I know, but remember. Remember." The memories came rushing back to her. Celestia standing over her, gently guiding her as she learned to master the night sky. Celestia teaching her the history of Equestria with a never-ending patience. Celestia and her, playing hopscotch together. Celestia and her taking a vow that they would rule as two parts of the same whole, for the interest of all of Equestria. Celestia's warm, computational smile as the crown was placed upon their heads. Her lips tweaked at just that angle, a strand of pink hair slightly disrelished and out of place, that look on her face that said she was planning a prank… that was the big sister she had always loved. Always. I still do love her. My big sister.
"I will keep her safe, Mother, Father. I would sooner die then let anything harm her. I swear it on the sun and sky."
But she had grown more serious as she had become older and after Discord had toyed with her mind during the short time he had usurped their rule, turning her against her elements, laughter, kindness, generosity, she had… changed. She had forgotten how to laugh, given to her subjects what was not hers to give, like taking away an hour of Luna's… no, Nightmare Moon's, she was Nightmare Moon… night, turned a deaf ear to Luna's complaints…
She recalled betrayal, so deep it was as if her heart had literally been sawed it half, at Celestia's announcement. She recalled desperation, and a chill wall that Celestia had put up to stop her feelings from interfering with her rule. She recalled repression and the worst loneliness she had ever felt in her entire night.
"Remember, sister."
"I remember. You are not my sister. I had one once, but now I have no sister. I have no sister."