Luna didn't feel well tonight.
The night itself wasn't unlike any other night, but for Luna, it was particularly painful. She had wanted to forget about it, to pretend it never happened, but she couldn't. The more she tried to forget, the worse she felt. During the day, she hadn't felt well either, but since she spent most of her days sleeping, it hadn't bothered her much since her exhaustion from the previous night's duties minimized it. Now that she was rested, she felt it all in full force, enough that it came close to being a physical ailment, as her stomach had been slightly aching since she woke up.
Luna could not stop staring at the moon she raised, yet looking at it only encouraged her grief. For a moment, she cursed her memory, gifted to be so much more vast than the average pony's. Were head trauma not a concern, she'd give herself a concussion if it guaranteed loss of all memory about this night and the events that led to it.
"Stop! Not another step."
She winced as she remembered saying those words. Only who they'd been addressed felt more painful than the words themselves. Truthfully, she couldn't recall if she said them willingly or if she'd already been consumed by the darkness of her emotions at the time. Either way, it didn't matter. They'd come from her mouth. The thought they may not have been said of her own will was no comfort in the slightest.
"Did you really expect me to sit idly by while they all basked in your precious light?"
The words of her envy. At the heart of the matter had been Luna felt unloved, but as was natural for anypony, her feelings grew worse from being left unchecked. That feeling of being unloved grew into bitterness and envy from watching her sister receive what she desperately longed to have. No, she hadn't wanted to take it from her sister. She'd wanted to share it. When all her efforts failed, that envy grew into hatred. Deep hatred that she lost control of and that eventually consumed her until her transformation into Nightmare Moon.
"There can be only one princess in Equestria. And that princess will be me!"
For the following millennium, the first set of her words had technically been correct. She just hadn't been that princess, as she so foolishly thought. The events that followed after her furious rant were blurry. At most, she could remember little more than Celestia declaring she wouldn't fight, striking Celestia down, and finally, Celestia banishing her with the elements. But she wanted to forget it all. She wanted every minute of that night forever gone from her memory. But a wish was all it would be.
Luna grieved for the time she'd lost to her exile. Her and her sister's incredibly long life spans did nothing to comfort her about all the time she lost and could never get back. Granted, that wasn't entirely true, but it'd only erase the events in history, not her memory. Plus, she wasn't selfish. Not anymore anyway. In the end, it hadn't been worth it. She was uncertain she deserved to be grieving over this. It was her fault. But she couldn't control it. It hurt too much to stay buried tonight.
"I am sorry, Celestia... Equestria... all of you." She choked out the words as she finally gave up her self-restraint and let herself break into quiet hysterics.
Celestia was surprised she hadn't collapsed. She couldn't decide which was more aggravating: listening to the petulant whining of the snobbish nobles during her court or having to intervene in their bickering between one another like she was a parent. It was truly the only responsibility of hers she despised with a passion arguably hotter than her sun. With the day finally over, she could put it out of her mind. At least, until tomorrow.
Before Celestia could retire to her sleeping quarters, one of her guards approached her as she was making her way.
"Is there a problem?" she asked politely, though her weariness was obvious.
"I apologize, Your Highness, as I know it is not my concern," the guard stated, "but it seems Princess Luna is troubled."
As if by a spell, Celestia was instantly alert. At times, her sister's name seemed like a magic word. Everypony in the castle knew the one guaranteed way to get Celestia's attention and concern was to mention Luna.
"What do you mean by troubled?"
"It is not our place to ask her of her plights, but we grew concerned when we did not see her after she woke," the guard explained. "We dared to check her whereabouts, purely out of worry we assure you. It seems she has been on the balcony for some time and she is in distress."
"Thank you. Don't worry. I'm not upset you and the others cared enough to check on Luna," Celestia told him. "I will go see her for myself. Please resume your post."
"As you wish."
Celestia hurried to the balcony. Though she was still tired, she was not going to sleep until whatever ailed Luna was solved. It didn't matter whether it was an emergency or not.
As she climbed the staircase leading up to the balcony, she heard a faint sound that grew louder as she walked further up. It indeed sounded like somepony crying. Sure enough, Luna came into view, crouched over and sobbing with her face hidden by her hooves. Her sobs were briefly interrupted every so often with small coughs and gasps for air, and she was shaking like a leaf. Luna had never been one to talk about her troubles unless asked and sometimes, not even then. Getting Luna to talk about her problems could prove harder than pulling an unloose tooth. But Celestia knew much better than to leave Luna alone when she felt so badly. The last time she did...
The last time she did...
As soon as that thought passed through her mind, she knew what was wrong. It had slipped her mind as she spent the day tending to her duties, but she remembered now. Tonight was the anniversary.
"Of course," Celestia thought to herself, sighing sadly. "Of course she's upset."
With Luna's return, Celestia had hoped they could put the whole matter behind them and pretend it was nothing more than the fable it'd become to Equestria's citizens. At the same time, she had known it was silly to expect that right off the bat. Luna had a lot to deal with. She had to recover, she had to adjust to society, and heaven knew she and Celestia had a lot to discuss at the time. Still, Celestia hoped time would allow them to reach the point of no longer minding those events. Perhaps even that hadn't been realistic.
Celestia quietly walked out onto the balcony and stood next to Luna. If Luna had noticed and told her go away, she would've done so without objection. She could understand if Luna didn't want to be around her tonight, though it would've broken her heart. She gently stroked Luna's back with her hoof. When Luna didn't respond, she tried caressing the side of her face. That also failed, so Celestia set herself down and draped one of her wings over Luna's body. It certainly wasn't easy to watch her sister have a breakdown, but she figured she'd simply have to wait for Luna to quiet.
While she waited, Celestia thought back to that night. She had been looking for Luna throughout the castle and found her in the throne room. Even before she so much as spoke, Celestia had been able to tell something wasn't right. Her sister was glaring at her menacingly, as if Celestia offended her from just daring to step into the throne room.
"Stop! Not another step."
At the time, Celestia hoped she misheard those words. She knew she and Luna had problems, to put it lightly, but she did not want to believe her own sister was threatening her. She had frozen her footsteps, not out of fear, but out of shock.
"Did you really expect me to sit idly by while they all basked in your precious light?"
Celestia had wanted to reply to that, but she could think of no words. Aside from it being true, as much as she hated to admit it, Luna's voice had taken on a dangerous tone. Celestia wasn't afraid of Luna or her threats, but of what seemed to be happening to her. She knew well of Luna's anger toward her, but she assumed her envy to be nothing more than the ordinary feelings of rivalry most siblings shared. It was that remark that made it clear Luna's feelings had developed into something beyond that, and Celestia had failed to notice.
"There can be only one princess in Equestria. And that princess will be me!"
After that sentence was spoken, Luna had begun to transform. Celestia had only been able to watch in horror, unsure what to do or if she could do anything. She wanted to interfere, to try to save her, but the transformation happened within seconds. Too quickly for her to think of any options if there'd been any. In her sister's place stood that evil mare, but it was no longer her sister, something the mare herself made clear when Celestia addressed her as "Luna" and insisted she lower the moon. But Luna was in there somewhere and for that reason, Celestia didn't possess the heart to fight her. Even as she fled away, dodging Nightmare Moon's attacks, she didn't retaliate, fearing she would harm Luna in the process.
Only when Nightmare Moon struck her down and she recovered did she realize the situation was too dangerous. Nightmare Moon could not be reasoned with. Celestia finally resorted to fighting, using the most powerful artifacts they possessed: the Elements of Harmony. She knew one pony was not supposed to bear all of the elements at once, but she had to try. She cried as she directed their assault at her sister, but it'd been her only hope. When it was all over, Celestia fell to the ground in exhaustion, but she looked up ahead of her, smiling a little because she expected to see her beloved sister back to herself, even if collapsed as well.
But she hadn't. Only when she looked up at the moon did she realize what happened. She had banished Luna with Nightmare Moon. In that moment of realizing what she'd done, it all came crashing down. This didn't have to happen. She could've prevented it. All she would've had to do was listen. But only when Luna threatened her had she done so. For the next millennium, that knowledge haunted her. A thousand years with her sister lost because she failed to care.
Attempting to shake the painful thoughts from her mind, she returned her attention to Luna. Much of Luna's sobbing had finally ceased, but some tears and light gasps still persisted. Celestia lied her head over Luna's neck to nuzzle her a few times. Luna opened her eyes and finally looked back at Celestia, though she looked like she could become hysterical again at any moment.
"I know what's upsetting you," Celestia whispered. "It's alright to cry, but I promise I will never separate us again."
"You didn't have a choice," Luna mumbled, her gaze shifting to the moon again.
"Yes, I did." Celestia gently turned her sister's head to face her again. "I don't know if you ever realized this, but my intent was to banish Nightmare Moon. I did not intend to send you away with her. But it did not have to reach that point. I could've paid attention and heard you out instead of pretending there wasn't a problem between us."
"That does not excuse my actions," Luna replied.
"But mine are not excusable either," Celestia insisted. "I couldn't do anything about the citizens not caring for your night, but I could've disallowed you to think I didn't love you."
Though Celestia wasn't wrong in that she had ignored Luna's troubles, Luna had long lost any heart she had to blame her sister for her wrongdoings. As far as she was concerned, Nightmare Moon was her sin to bear alone and Celestia didn't need to bother herself with it.
Before she could say more, Celestia moved to lie at Luna's side, but draped her wing over Luna's body again. Celestia could now plainly see Luna's ordinarily sweet blue eyes were puffy from all the crying she'd done.
"Luna, if you want me to leave you with your thoughts, I will," Celestia told her, keeping her soft tone. "But what I said is true and you can admit it. You did not go down the path of Nightmare Moon for fun, and if I could interject your thoughts every time you treat it like I had no part, I would. But I have a request, if you don't mind."
Luna said nothing, but kept her gaze on her sister, which Celestia took to mean "okay".
"Maybe we cannot pretend it never happened, but if we're to acknowledge an anniversary, can it be of your return instead of your loss?"
Though she only expressed it with her eyes, Luna became curious.
Celestia continued. "When I finally saw you again as Princess Luna, I felt a happiness I hadn't in the thousand years you were gone. I was scared you were still angry, but tried to hide it, because I wanted you back so badly. I didn't expect you to come running to me, but when you did, all that weight lifted. We'll never get back that time, but we have so much more to share. So, can we celebrate that anniversary instead of remembering this painful one?"
Luna stared back at the moon for a few moments. When she looked back to Celestia, a small smile formed on her face. "Yes. I would like that." She sat up and wiped her eyes clear. Celestia also sat up and they shared a tight hug. Celestia smiled with relief, glad she'd been able to help.
"I love you, my little sister. Do not ever forget that. And I'll ensure I do nothing that could persuade you otherwise."
"I love you too. Thank you so much. And Celestia?"
"Yes?"
"If you're worried about it, you have been an amazing big sister to me. It was worth the wait."
Big smiles from both ponies followed and there was no more sadness to be felt throughout the night. In that instance, they wanted this moment to last forever, but knowing they'd have to let go eventually, they enjoyed it while they could with the warm glow of moonlight in the distance.