The world around her was dark. Nothing but an endless black. She could feel herself moving, feel herself shouting, yet she knew it wasn't her voice. It was deeper, she could feel, more terrifying. She knew, now, where she was. Trapped in her own mind, swimming in and out of consciousness, an evil force using her body. It hadn't had the power to erase her completely; just to push her away and trap her. This was Luna's prison.
Moon couldn't erase her, even if she had the power. Erasing her would be the same as killing her. Though Moon now controlled it, the body still was tied to Luna's soul. Luna's death would only result in the destruction of both mares. So Luna was trapped; a prisoner in her own body. She could feel every physical pain that Moon could, but she could not speak, hear, or see. Moon controlled that. All she could do was feel. Her body ached, she assumed from the transformation.
Luna thought of her sister, alone, left to defeat Moon, and rule the kingdom by herself. She thought back to her younger days. Why hadn't she told Celestia? She would've understood. She would've been careful. She might have, with her sister's help, learned to control the curse. Her poor sister; shut out and left to grow up alone, and she never knew why. And her poor parents, left to raise a filly whom they knew would either fall victim to Moon's possession, or been killed off by an angry mob.
"It's funny," she mused bitterly "how you only realize how foolish you were, how miserable you made everypony else, only when it's too late. How you only see clearly after you've been so blind. Mama, Papa, I'm sorry this happened. I'm sorry you had to constantly fear your own daughter while also fearing what others would do to her.
"And, Tia, my dear sister, I'm so sorry you'd had grow sheltered away from me, that we hadn't been able to grow up together as sisters." had she been in control of her eyes, Luna would have cried by this point. "I'm sorry we were so distant, that we were sisters, best friends, forced to spend their lives apart. I'm so sorry." She began to sing.
"Sadness burns within me like stars aglow. I've had to be thrown out by the only friend I've ever know. There's no way Moon can win, and now I wish that I had told you all that time ago." she could feel herself fading out of consciousness, "Life's too short..."
Celestia stood on the balcony outside her bedroom, staring up at the Moon. A black silhouette darkened it's surface; her sister's outline. It'd been a few hours since the mare had appeared on the Moon. After Luna had transformed, Celestia had escaped Nightmare Moon's wrath, rushing back to Canterlot. On her way home, she'd convinced herself on what he had to do. Taking the Elements of Harmony, she returned to face Nightmare Moon. The mare closed her eyes, thinking back on what had happened.
Celestia landed on the outer balcony of Nightmare Moon's castle. The mare in question stood in the center of the room, grinning wickedly at Celestia. The young princess moved into the room, saddlebags clinging tightly to her sides, the Elements tucked safely within.
"Ahh, Celestia," Nightmare said calmly, "welcome back to my humble palace. I'm so glad you've returned. I wanted to thank you."
"Thank me?" Celestia coldly replied "What reason do you have for thanking me?"
Nightmare Moon stepped closer to the Solar Princess. "Oh, very much, my dear. After all, none of this," she gestured to herself with a hoof before curling it under and giving her spread wings a flap, "could have been possible without you ." she slammed her hoof down, punctuating her sentence.
"Me? What's any of this got to do with me?"
Nightmare Moon chuckled cruelly. "When I merged myself into Luna's body, I gained access to ALL of her memories. I, or rather she seems to recall that, on the Night I cursed her, it was you who woke her up. It was you who made her come play with you." By now, Nightmare Moon was circling Celestia, taunting her. "But, as if getting you own sister cursed wasn't enough, you helped me gain control over her."
"How could I ha-"
"I gained power through her anger, her fear. She grew angry and scared whenever you tried to force her to play your foalish games. The final straw was merely hours ago, when, again, you tried to force her to do what she knew she couldn't do. You never stopped to think of what she wanted, or why your sister was isolated, or why she refused to come back with you. No. All you cared about was. Your. Self!"
"ENOUGH!!!" Celestia shouted, stopping Nightmare Moon in her tracks in front of her. Her horn was flared, the Elements gripped in her yellow aura. They began to glow. Before Nightmare Moon could react, the Elements had activated and fired a multicolored beam of light at her. She shrieked in pain as the light burned at her from the inside out.
Then she was gone.
Celestia had returned to Canterlot, with the Elements she no longer controlled. She used them against the other bearer, breaking the harmony. She, nor Luna, could ever control the Elements again. The ponies of Equestria demanded to know what happened.
And so she told them.
She told them what Luna had told her, adding in what she had already known. She ended with Nightmare Moon's transformation, and defeat. Her punishment was an eternity on the Moon.
But she'd lied.
Alone, she couldn't wield the Elements' full power. Nightmare Moon would only be banished for a thousand years. She wouldn't see her sister for a thousand years.
A clock in her bedroom chimed five o'clock, time for the Sunrise. Her magic flared as she pulled the Moon from the sky and lifted the Sun in it's place. The Sunrise was especially beautiful that morning; a sign of an era of hope an prosperity in the wake of Nightmare Moon's defeat. Celestia looked down at her ponies, celebrating Nightmare Moon's defeat; celebrating her sister's banishment.
She levitated a few large pillows from her room, laying down on them as she watched Night turn to Day. Nightmare Moon's words swirled around in her head. As much as she tried to push them away, to tell herself that Moon had just been trying to get into her head, to psyche her out, she just couldn't. Because Nightmare Moon had been right. She'd been a spoiled brat who only cared for herself. She closed her eyes, a few tears dripping down.
"Life's too short," she sang, "to be such an oblivious fool. So thoughtless that I couldn't see," she took a shaky breath, "that life's too short to be so desperate for a sister's love,that I only ever thought of me. I should've seen it clearly; been the sister of a good sort. And now all I know," tears now flowed freely, "is life's...too...short." she collapsed fully on the pillows, sobbing.
"Oh, Luna," Celestia whispered, "I'm so sorry."
She threw her head back with a shriek that echoed throughout the kingdom and the souls of everypony in it.
"LUNA!"
Despite Celestia's power, she could not see the future. She had no clue as to how her sister's story would change over the years into a foalhood campfire story. She didn't know that her sister would become a mere character of which ponies would tell to their younger sibling to scare them. She couldn't see that an entire holiday inspired by the fear ponies held for said 'fictional' character would be created.
All she knew was that the next thousand years of her life would be spent frozen in a nightmare.
THE END