"1000 years... You sent me away for 1000 long years. You never reached out, never tried to make amends! Did my presence truly mean so little to you?" Luna asked her elder, unhappy tears in her eyes.
"You were imprisoned for 1000 years on the moon, such was your sentence. But my sentence was here, to watch you rise and fall every night into the day, just out of reach." Celestia hugged her younger close. "Every day I rose the sun, I mourned to not see your face. And every night, I mourned to see you, but not ever be able to reach out. To speak with you, to tell you how much I loved you and missed you. The elements cut me off from them and punished me for my actions as well."
"H-how can you be so welcoming of me? How can you have ever even missed me after what I did?" Luna wept, her tears dampening the fur on her sister's chest.
"Sssh, we don't have to bring any of that stuff up just yet. Those times are past, and we are not the ponies we once were. We can talk about those things when you're settled again and truly ready. In the meantime, I'm just so, so happy to have my little sister back."
A few years later...
"But we've never talked about it, have we?" Luna asked her memory. She awaited her elder sister in her room, as she promised to speak with her more. But the room was almost terribly nostalgic to her for a place she'd only been to a few times in the last few years. The conversation rang in her head like a skipping record, playing again and again until she felt like she was watching the ghosts of the past sitting on the bedroom floor. Where they'd cried together that day, where she'd stayed when she first returned from the moon. Her sister had wanted to keep her close for as long as she could. This is where they talked and got to know each other all over again. It was hard to stand there alone, and she silently hoped Celestia would be along soon.
She had flown up from the courtyard about 30 minutes before. She had spoken with Cadance for a while, and ensured that she better understood the ancient fight between Celestia and herself. Or at least her side of it. She still felt sick from retelling it. For so long she'd been avoiding it, burying it deeper and deeper into her heart. But how could she tell another pony that she tried to kill their own sister without feeling like a monster? How could she say that she meant to destroy everything that Celestia had created just for cruelty's sake? How could she admit that she'd become so jealous of what her sister had; the companionship, the adoration, the respect of the citizens Luna so longed to please, that she became blinded to wrong-doing. That she'd killed ponies to sate her revenge, and to see her sister hurting.
These things were met with the disgust that Luna expected, but despite the obvious repulsion, Cadance nevertheless stayed to hear the end. What surprised Luna most, is that after a long period of silence and deep thinking on both their parts, Cadance forgave her. She explained that she could feel every ounce of remorse Luna held in the situation, how her heart had obviously been healed upon her return, and that if Celestia could forgive her for what she'd done then she had no reason to hold anything against her either. Her talk with Cadance was then ended when Shining Armor came out from the castle, in search of his bride. With a silent nod of understanding, they dropped their prior subject and made small talk before parting ways for the evening.
After a few more awkward minutes, hoofsteps began to echo up the stairway leading to Celestia's tower. They were followed to two other sets of hooves with much smaller gates. Luna knew her sister was approaching, and for a brief moment she was filled with the urge to flee, to fly away as fast as possible before Celestia could open the door. With a slight tremble and a hard swallow, she resolved herself to stay. This time, she had questions, and she needed answers.
"I chose it!"
"I know." Celestia scraped awkwardly at the floor, her golden horseshoes removed, allowing for her well manicured hooves to glisten in the moonlight on the balcony.
"Then why won't you take it back? WHY?! I just can't understand how you can keep forgiving me, after everything that happened! I chose to be Nightmare Moon! I chose to come after you! I killed ponies in that pursuit, Celestia!" Luna sputtered through tears.
"I cannot take back your crown, Luna." Celestia wailed. "The ponies of Equestria need you, and you cannot just give that up."
"Need me? Art thou truly serious? Have you gone mental?" Luna retorted, shaking. "Celestia, I gave up this crown when I made the decision to attack. Not just you, but the ponies you now expect me to lead. I cannot in good conscience go on with this anymore!"
"Shush!" Celestia hushed, "We must not make this too loud, sister. The walls have eyes and ears, and we mustn't make this into public business just yet." With a sigh, Celestia removed her own crown, and stared into her sullen reflection staring back. "So much time has passed since those events. And you are not the same pony you were, nor will you ever be... That much is my own fault. I ignored your needs when you needed me to listen most, and I'll regret that forever. But I firmly believe that your past makes you all the more fitting to rule now. Everything you've been through and learned from our mistakes, makes you stronger and wiser than any other pony I know. I wouldn't want anypony else ruling by my side."
"Perhaps you're not hearing me, or understanding me: I. KILLED. Ponies." Luna said through heavily, shocked breath. "I'd be flattered by what you've said if it weren't so crazy! I'm a murderer, not a princess. I need to punished, no rewarded for it! If it was anypony else, they'd be in the dungeons right now!"
"You paid your sentence, 1000 long years of it for your crimes.The elements sentenced you, and have finally released you, can you not accept that your debt has been paid in full?" the elder sister closed her eyes, knowing well what would be said next.
"NO! No, I can't accept it! Things cannot just go back to the way they were before all this happened, you cannot take back death!" the blue alicorns feathers ruffled, and her eyes were harsh and filled with malcontent. "And you cannot expect me to believe that after 1000 years without me that the ponies of Equestria actually need me. Not after you've done my job all this time without flaw."
"That's not true!" exclaimed Celestia. "Every dawn, and every dusk, it took all my strength to move a moon I've never been magically connected to! I cannot enter ponies' dreams and help them on such an individual level, and I cannot do this anymore. Not without you." the elder princess broke down into tears, dropping her regal crown the floor.
"I'm sorry, but whether or not you need me is irrelevant. I am guilty of something unforgivable, sister. Please, to ask me to step back into the shoes of a princess is a torture I cannot bear." Luna removed her own crown and rested it upon the floor next to where her sisters lay dropped. With a sigh, she sat near Celestia and contemplated what to say next.
"You are not the only one who is guilty..." Celestia said through sobs. Her hair had fallen over her face, now hidden in the shadows.
"What?" Luna looked to her sister in an uncomfortable mixture awe and suspicion.
"You aren't the only guilty pony..." repeated Celestia. "I... I have something to tell you. A-and you may not forgive me... It was me. It was always me, from the very beginning."
"What do you mean?"
"Luna, your downfall was my plot. I was so wrapped up in myself and ruling that I lost track of what was really important to me, what gave me the position I held to begin with. The truth is, I don't deserve to rule either, and I haven't for a very long time." Celestia explained. Luna sat, mouth agape, a mixture of anger and horror frozen upon her face. "When the ponies turned against you, it was me who poisoned them. When they feared your night, it was me who encouraged them. When you needed me most, I was your worst enemy." Luna slid back from her sister, hesitant to even breathe.
"My punishment for my crimes was to simply try and live with myself. To do my work, and yours. To see you rise and fall every day and every night. 1000 years without the one pony who ever actually made me happy. At first, I abandoned all good sense. I left our old home behind to start anew, but nothing filled the void of your absence. So I filled this castle with reminders of you, to remind me that behind Nightmare Moon, the real monster was me."
"I-I don't understand... you always looked out for me. I mean, you were manipulative and often controlling, but this... this is evil." Luna teared up. "Everything awful that I am, is because of you?"
"Yes..." Celestia's tone was beyond sorrow. "I'm sorry. I'm so, so sorry. I understand why you must hate me, and why you stay so far away. I want so desperately to make things right, but I can't. I can't change what I did to you, I can't return the lives lost to their families, I can't change how you must think of me now." she continued. There was a long pause of silence.
"I have been feeling the exact same way for a millennia." Luna said sullenly. Celestia burst again into tears, sweeping her sister into a deep hug.
"I don't expect you to forgive me for what I've done... and if you really wish to give up your crown, I cannot stop you. But I beg you. Stay here at the castle for a while. Please think things over, and reconsider leaving. Equestria needs you so much more than you may know."
"I... yes. That would be fine." Luna gave in. "But we'll need to discuss this a lot more in the future. For now... I need to think about some things, and I'm sure you need to rest now for the morning." Pulling herself from the awkward hug as Celestia agreed. Luna tried to not make eye contact with her sister and readjusted herself as she prepared to leave.
"Right... have one of the guards direct you to your room. We always have one prepared for you should you ever decide to stay.." Celestia smiled meekly. Luna returned the smile, and felt genuine for the first time in months.
"Thank you, sister, I'll be sure to ask."
Luna shut the door behind her, assuring the guards that she'd be fine without them keeping watch outside the door. She was exhausted, but her troubled mind prevented her from resting just yet. She'd been talking with her sister into the wee hours of the morning, dawn would be in a few short hours, and she pitied how tired Celestia would be for the coming day.
"Perhaps neither of us are fit to rule..." she whispered to herself. "But for my part, perhaps there is something I can do. If I pay penance enough, maybe I can be redeemed." Luna's magic flared to life, shutting the curtains tightly and using linens to block the cracks around the door. "Forgive me sister, but if you refuse to give me punishment yourself, then I must construct my own." With another bright flare of light she set to work.
A few hours later Luna smiled weakly as she grasped and lowered the moon. Re-entering the room from the small balcony running outside of it, Luna closed the heavy curtains again behind her. Like a zombie, she made her way over to the neatly prepared bed and slid beneath the silky covers. It did not take long for her to drift off and into a dream.
"Greetings Tantabus. I am ready. Please, do your worst."