Prologue
It was night. It was one of those nights where she could not sleep, because, as calm and as cool as it may be, there is always the feeling that something needs to be thought about, that something needs to be discovered. The feeling that some great or horrible realization waits just beyond the doors of time, and she's about to pass through them.
On this night, Celestia found herself wandering the castle halls, as had happened many times before. Her position as a princess has given her much to think about. But tonight her mind was focused on the one thought that haunts her.
Moonlight shone through the tall windows of the castle hallway. Through each window she passed, Celestia's eyes would stare far into the distance, her mind going numb as her empty gaze fell upon the source of light.
She had done this many times since Luna had fallen, contemplating the consequences of her actions many years ago. She had fought within herself, struggled, suffered, and searched for peace, but all she had accomplished, was condemn herself further. She knew that, after so much time had passed without relief, she probably would never feel peace again, even if Luna came back.
Celestia just felt. Felt and stared. Stared at the one symbol of her deepest regrets.
And yet she was calm.
She couldn't cry anymore. She had already cried a great deal. Celestia thought about that, and wondered if that meant that she had grown heartless, apathetic towards her actions and their irreversible consequences.
No, she concluded, because I can still feel all the pain of regret, despite my lacking display of it. Her eyebrows furrowed. She had stopped walking, and was now sitting in the glowing spotlight coming through one of the many windows that constantly let in a beautiful reminder of her greatest mistakes.
One could say there was peace here. It was calm, quiet, and not a movement to be seen. But in the mind of one who has much to think on, there is never peace.
A small sound echoed through the halls, drawing Celestia out of her daze. Turning her head, she locked her sights in the direction of the sound.
She waited.
Hearing nothing, she turned away, her mind returning to it's seemingly eternal prison.
The sound again.
Waiting for a moment, listening intently now, Celestia stood up, and began to make her way towards it.
As she passed the many passageways, she scanned for any movement, any indicators of others who might have felt to stay up as she did.
In the middle of a certain hallway, an orange light bathed one of the walls, spilling from one of the doors opposite. Celestia knew all too well which door that was.
Walking up to the door, she looked inside. As she expected, she was met by a vision of the castle archives. Books filled every shelf of the small circular room.
Celestia checked the lock on the door, finding that it had been picked with magic.
Looking around, she searched for any signs of damage or theft. Seeing nothing from the entrance, she walked in cautiously, ready for any intruder. Many of the shelves appeared to be completely untouched.
Rounding one of the corners, Celestia saw a book on the floor, open to it's final page. She continued forward, revealing that, next to this book lay a small purple unicorn, attention locked on the pages of the tome in front over her.
"Twilight?"
Twilight gasped, jumping to her feet. "P-Princess!"
"Twilight, what are you-...?" Celestia's eyes were pulled from the small filly to the book on the floor. Across the page, big scratches of black ink spelled out four words. Dread filled her as she realized which book it was.
Celestia quickly slapped the book shut with her magic, making Twilight flinch. She lifted the book up to herself to inspect it's cover. On it's front, were embossed the words, 'The Diary of Princess Luna - Fourth Volume'.
"Twilight, what are you doing here?" Anger welled up in her voice.
"I-... I was just-"
"Twilight!-..." Celestia stopped herself, closing her eyes and taking a deep breath before continuing. "Twilight, you know that these are the castle archives, and that these records are locked in here for a reason. Why did you feel that you could come in here, unaccompanied, and without permission?"
The shaking young Twilight lowered her head, her eyes filling with tears, her ears back. "I'm sorry princess. It won't happen again."
"What did you read?"
Twilight didn't even look up at Celestia, her body trembling more now.
"Answer me!" Try as she might, Celestia's emotions couldn't be hidden.
Slowly, Twilight's lifted her head, but not enough to see Celestia's eyes. "I-... I-... All of it."
Celestia had feared this day would come again, the day that a student of hers, too curious for their own good, learned who Luna was, and where Nightmare Moon had really come from. Celestia felt that her past could not be known, that it was too dark to be forgiven, and that if anypony were to learn what she had done, she would not only lose the trust of all of Equestria, but there would be doubt, uprising, chaos...
And now, the one student that she had hoped would help undo this past, had found the truth far too soon.
Celestia knew what had to be done.
"Twilight, open your mind."
Twilight's head shot up, her eyes wide, her trembling doubled, tears rolling down her cheeks. Instinctively she began to back away. "I- I'm sorry! I didn't... I didn't know! Please! I'll do anything!"
"Twilight," Celestia said even more sternly than she already had. "Open. Your. Mind."
"I'm sorry, Princess! Please! I'm sorry!" Twilight's tears were flowing freely now. Her eyes scanned the floor back and forth desperately, looking for a way out, knowing there wasn't one.
A glow emanated from Celestia's horn, "I understand, Twilight. But for some things, there are no exceptions."
Twilight's small body shook violently now, and after a few seconds, she collapsed, weeping loudly, "I-*hic*- I don't wanna go to the moon!" She curled into a ball, giving up. "I don't wanna- *hic* -forget my lessons! I don't- *hic* -wanna leave!- *hic* -I'm sorry!- *hic*"
The sight of the young filly in hiccuping sobs stabbed at Celestia's heart, gauging wounds in her resolve. But she knew, that if she didn't do this, all hope of saving her sister would be lost.
Trying to be gentle, Celestia spoke to her student as a mother would to her daughter. "You need to open your mind so I can protect you from the mistakes of my past.
"I'm not going to send you to the moon. I'm not going to send you home. You will stay with me here in the castle and we will continue your training. I love you Twilight. You are my favorite student. But you cannot know the things you now know, because those memories are mine only until I fix them.
"So please, don't make me open your mind for you."
Twilight lay there, curled up and shivering, her eyes closed, her cheeks wet. Celestia stood in silence, watching her faithful student make a frightening decision. This wasn't what Celestia wanted for Twilight, but her faith in her was enough that she knew that she would make the right choice.
A red glow from Twilight's horn signaled the end of Celestia's fears, and she began her work.
Going through Twilight's memories, she was reminded by Luna's words of all the wonderful moments she had with her beloved sister, and of all the horrible things she had done to her. She saw the words of her sister's anger, and cringed at the final words that sealed her fate to that of Nightmare Moon. When she arrived at the most recent memories, she saw herself, her own anger and fear coming out on an innocent filly who simply didn't know any better.
Finding the memory of the moment that Twilight opened the archives door, Celestia purged everything that came after it, making it as blank as it was before it could be filled with forbidden truths, and the terrifying wrath of a mentor who was just as fearful of getting caught as she was.
When she was done, Celestia felt moisture on her own cheeks. Wiping the tears away with magic, and wiping Twilight's as well, she put the book back on the shelf, picked up Twilight and placed her by the archives door, facing inward, before she could wake from the spell.
Celestia walked into the hall, stood a short distance behind Twilight, and waited.
Shortly after, Celestia saw that the spell had worn off, as Twilight had put her hoof to her head.
"Nng... what was that..?"
"Twilight?"
Twilight gave a small jump, turning around. "Princess Celestia... I thought... um..."
"...that I would be asleep, and that you could have a look around, unaccompanied?" Celestia gave a gentle smile, a façade disguising the disgust and contempt that she held against herself for what she had just done.
Twilight gazed at the floor, unable to look her in the eye, and nodded her head. "Am I in trouble?"
Remembering her callous tone just moments ago, and not wanting to emulate it again, Celestia spoke softly, yet sternly. "Well, no... and yes."
Twilight kicked at the floor with her forehoof. "I'm sorry."
"It's okay. I forgive you." Celestia used great effort to sound as kind as she could, trying not to reveal her own nervousness. "What are you doing here? Looking for books to read?"
"I was just curious." She looked up at Celestia.
"I know. But you should know better then to go snooping around in the castle at night. What if something were to happen to you?"
Twilight said nothing.
Celestia knew that Twilight felt bad. She always felt bad for even the smallest of mistakes. She held herself to such a high level of discipline, that it was sometimes too high, requiring Celestia to calm her, comfort her, and encourage her whenever she fell short of her own expectations.
"Come, let's get you to bed."
Twilight, still hanging her head slightly, walked out from the entrance of the archives, and Celestia magically closed the door behind her.
Having led her apprentice to bed, Celestia once again found herself looking through the same window as before.
Oh, Luna... I have not changed. I have not yet let go of my pride. I'm still afraid of the things that I've done. I still... I still lust for the praise that he always gave you. Celestia gritted her teeth against the pain that ripped at her heart and mind. I still manipulate other ponies. I still use forbidden magic to cover my sins. Even my most faithful student has suffered because of my lack of control.
She closed her eyes, forcing out tears that hadn't fallen for hundreds of years, and hung her head as her own student had done not long ago.
"Why?" Her hoof slammed into carpet below her with a muffled thud. "Why can't I be better? Why can't I admit my mistakes?"
Thud.
"Why couldn't I just listen? Why couldn't I just let you be better than me?" Thud. "Why couldn't I just move on? Why couldn't I be a faithful student like you, Luna?" Thud."Why did I have to-... to-... send you away?" Thud. "Why wasn't it me instead?" Thud.
"Why? Why? Why? Why-..."
Her painful sobs echoed down the halls of the castle. She didn't care who heard. She just wanted not to feel anything anymore. She knew what she had done. She knew why she had done it. And it haunted her, along with four thick black words, scratched across the last page of the last thing her sister wrote.
'You always forgot magic!'
On the floor of an empty hallway in a castle overlooking all of Equestria, the princess of the sun wept in the light of her greatest regrets.