Celestia quietly entered the cave, carrying the things she wanted with her in a field of magic. A bed mattress covered with a fitted sheet, some pillows, a blanket, and a framed picture of her sister.
She gently set down the mattress and arranged the pillows on it to her liking. When she was done, she took off all her royal regalia, lay down, and drew the blanket over herself, snuggling down into the softness. Finally, she carefully set down the picture in front of her on the mattress, reaching out a hoof to gently place it on the glass.
At last, it was finally time for her to rest. She found her mind drifting over the events that lead her here...
"Celestia, look what I've found!" Luna said excitedly, showing her an old piece of paper that she held in her magical grip. "It was in some of Star Swirl's old things! I think it's a prophecy!"
Celestia's ears pricked up at this. "A prophecy? Like the one that foretold you coming back?"
Luna nodded. "Exactly! I think this one is about me too! Look!"
Celestia stepped over to look at the writing.
For the moon so loves the world she will make a decision that will change everything. For the nightmare that wanted to bring the world darkness will leave it in light.
"What do you think it means?" Luna asked curiously.
"I'm not sure exactly, but it sounds like you're going to do something that will make the world a better place." Celestia smiled.
Luna smiled too, and then her smile became a grin. Her whole body quivered, and she finally gave up trying to seem adult and started prancing in place like an ecstatic filly. "Eee! This will be so great! Maybe I'll do something that will make everyone forget I was Nightmare Moon!"
"Oh Luna, nobody really cares about that anymore. It was so long ago." Celestia told her.
"I know, I know, but maybe I can finally make my mark in history. Something that will outshine what I tried to do as Nightmare Moon." Luna stopped dancing around and put her hoof to her chin. "But I wonder what it is that I'm going to decide that will be so important."
Celestia wondered too, but she only shrugged. "I don't know, but when it comes to things like this I've found that it's best not to try to make something happen, because it'll end up happening naturally anyway."
"True." Luna nodded. She looked the paper over again. "Do you think maybe this already happened when the elements changed me back?"
Celestia looked over the paper more carefully, but there were no other clues, nor was there a date. "Maybe. I mean you did come back and changed back into Luna and once again became the princess of the night. That changed everything. You also stopped trying to bring eternal night, which lets the day and night cycle go on as usual."
Luna looked disappointed. "Well, I'm glad that happened, but I hope this is about something else."
"Even if it is, it doesn't say when. Which means it could happen today, tomorrow, or not for another thousand years." Celestia pointed out.
Luna sighed. "I guess I might as well put this away and just forget about it then. Although..." Her face lit up. "Maybe I can find more prophecies about me!" She turned tail and galloped off to look through more of Star Swirl's old things, leaving her older sister chuckling behind her.
In the days that followed Luna wasn't able to find anymore prophecies, which made her pout for awhile but she soon forgot about it. She was still getting used to this age after having been away for so long. There were so many new things for her to try, and she seemed eager to try them all, as if she was making up for lost time.
Since the sisters had different duties they didn't spend as much time together as they would like to. Being that Celestia watched over the day and Luna watched over the night. Still, there were hours when they were both awake, and Celestia treasured that time. She had missed her sister for so very long, and now she was finally back.
Nightmare Night was coming up soon, and Luna was once again going to spend it in Ponyville, but this time she begged Celestia to come with her. They even decided to go in costume. Luna as a manticore, and Celestia as a timberwolf.
Then, the disaster. Scientists had discovered that a large comet was headed for Equestria. One that would hit in a weeks time, and after all their calculations, it was estimated that it would effect at least half of the world.
Celestia's heart sank as she felt what they were saying sink in. Point of impact and shock waves. Possible earthquakes and tidal waves if it hit the ocean. So much dust in the atmosphere that the sky, the sun, could be blocked for years. Food shortage. Animal extinctions. So many lives lost and in danger. So much suffering.
Celestia exchanged a glance with her sister, getting a determined nod in return.
The sisters worked nonstop with the scientists, both their own and with other races. Twilight, Cadence, and Shining Armor also worked with them. Ponies suggested everything they could think of to try. Magic, evacuation, shelters. Again and again the scientists would explain why something wouldn't work.
They were running out of time.
In the end, they reluctantly had to admit that there was no stopping the comet. All they could do was try to save as many as they could. Evacuations started, food was stored, animals were transferred. The problem was space and time. There just wasn't enough space for an entire world to fit in only half of it. Even if there was, there wasn't enough time to get everyone there.
Finally, there were only three days left. After everyone and everything possible had been evacuated to the other side of the world, the strongest magical shields in existence would be erected over the cities and towns that couldn't evacuate in time before the comet hit. Celestia prayed that it wouldn't hit an ocean. She didn't want her little ponies washed away.
Nightmare Night was the last day before the comet hit, and Luna came to her with a hopeful expression, wearing her costume. "Celestia, please can we not go to Ponyville?"
"What is there to celebrate Luna?" Celestia sighed as she stood on the balcony and looked over the abandoned city.
"That even though half the world may end tomorrow, and the other half will be changed as we know it, right now, tonight, we're here, we're alive, and we're together." Luna pointed out. "It's too quiet here with everyone gone. It's depressing. Lets go to Ponyville, most ponies are still there."
Celestia smiled. "You're right Sister. I'll go put on my costume."
That night, everyone played games, they ate candy and pie, they scared each other with pranks and stories. They had a costume contest. (Which Luna won.) It was as if everyone was almost desperately celebrating life, because they knew tomorrow that it might abruptly end. Loved ones covered each other in hugs and kisses. Some ponies drank alcoholic cider as if hoping that it would help them not think of the possible looming doom above them all.
Celestia wasn't sure that anyone slept that night. She knew she and Luna didn't. Twilight didn't either and neither did any of her friends.
"If this is going to be the last party we ever have, lets make it the best one." Pinkie Pie said in determination, and the others agreed.
Rainbow and Applejack both drank too much and sang silly songs. They looked ridiculous and Rarity took pictures of them. Possibly for future blackmail.
Even Fluttershy had come out to be with her friends, though she was nervous and kept casing anxious glances towards the sky.
The crusaders were underhoof everywhere, giggling and having a ball. Pipsqueak was running around with them, having just as much fun.
"Aren't you afraid?" Celestia heard Luna ask him at one point.
"A little." Pipsqueak admitted. "But if we all die then at least we'll all be in the afterlife together. I just wish that..." His voice trailed off and he looked at the ground.
"What do you wish?" Luna asked gently.
"I just wish I'd gotten my cutie mark first. It would've been nice." Pipsqueak sighed, but he soon perked up again, going back to his friends and leaving a thoughtful looking Luna behind.
The next day, though they were tired, most ponies stayed awake and spent the day with their family and friends. Luna and Celestia spent the day together in Ponyville, speaking of memories and just enjoying their time together.
As Celestia set the sun that evening and Luna raised the moon, everyone could see the comet coming as Twilight raised a barrier over the town and hoped it would be strong enough to withstand the blast.
"Celestia, I love you, very much." Luna said as almost everyone looked up at the sky.
"I know Luna, I love you too." Celestia said.
"So I hope that you can forgive me for what I'm about to do." Luna said quietly as she glanced over at everyone and then at her, her eyes filled with love, so much love, before looking back to the sky.
"What do you mean what you're about to do?" Celestia asked her, looking at her sister in confusion before she looked to the sky again, just in time to see the moon move... right into the comets path.
In a flash, Celestia suddenly remembered the prophecy.
For the moon so loves the world she will make a decision that will change everything. For the nightmare that wanted to bring the world darkness will leave it in light.
"Luna no!" Celestia screamed, trying to grab the moon in her own magic, to move it out of the way, but it was too late.
The comet hit the moon, and as it did so Luna stumbled and fell as if she too had been struck. Celestia leaped forward to catch her, as the moon in the sky cracked... and so did the moon on Luna's cutie mark.
"No! Luna! Luna!" She shook her sister's lifeless body as her empty eyes stared into nothingness and Celestia's cry echoed across the land. "Luuuuunnnnaaaaa!"
Later, doctors assured her that Luna had died instantly. There had been no suffering. No pain. As if saying that would help ease Celestia's own pain.
It didn't.
The moon now had a huge crater in it. It was completely full of cracks and pock marks. The atmosphere on that side of the moon was full of dust. It had taken all of the damage of the comet.
At first, scientists were puzzled by this. The moon was much smaller than the world. The comet should have completely destroyed it.
Then Celestia had found the letter.
Dear Sister,
I am so very sorry, but I have to do this. I have been using my magic to make the moon stronger ever since I heard about the comet. I know we both discussed how if we tried to block the comet with the sun or the moon that we risked permanent damage to them, but I must do this.
The world cannot live without the sun. All the plants would die, everyone would starve, there would be no warmth, and eventually the whole planet would become a lifeless ball of ice.
While losing the moon would cause a lot of complications and damage, the world could still survive until you figured out a solution to the problems it would create.
But I am going to use all my strength to make sure that the moon survives, even if it is badly damaged. I am confident that eventually magic will be able to heal it.
I know what this will probably do to me. Long have I suspected that we are ageless due to being connected to our elements. I'm so sorry Celestia, that I have left you to face eternity alone. If it becomes too much for you to bear, and you decide to find a way to join me, I understand. I'm sorry I didn't tell you, but I knew you'd never let me do it.
But first, I leave with you the duty to heal the moon. Take care of it for me. I am rather fond of it.
I love you so very much, but I also love this world, and I cannot bear for it and it's inhabitants to suffer when there's something I can do to stop it.
Love, Luna
It took time, but gradually Celestia was able to heal the moon, and she handled it as delicately as a newborn foal until not a single crack remained. She then used her magic to carefully create craters in the form of a head and horn.
The mare in the moon returned, this time forever.
Celestia also started to regularly do what she called an eclipse. The sun blocked by the moon, and, after scientists insisted on balance, the moon blocked by the sun. She did this to make sure the world never forgot Luna's sacrifice. The very sky honored her, and she made sure her name went down in all the history books.
Celestia indeed couldn't bear the thought of an eternity without Luna. She'd lost her for a millennium, then had her back for only a few short years. She couldn't deal with losing her again, not knowing she would never come back.
So she began to search all of Equestria for one who could be her successor, but again and again she came up empty. Finally she did the most selfish thing she could do. She courted and married a stallion only so she could get pregnant and have a foal.
As she looked into Bluenote's eyes and said her vows, as she pretended to be in love, as she beamed and pretended to celebrate, she felt nothing.
When she got the news later that she was indeed carrying a foal, as she smiled and pretended everything was wonderful, she felt no affection.
When she felt the first kick inside from a tiny hoof, and felt the heaviness in her belly with the new life, she nonetheless felt empty.
It was only when, months later, the baby was born and she saw that he was an alicorn, that she finally felt something. Relief.
Of course there was a sensation. Not only was he the only other baby ever to be born an alicorn, he was also the only male alicorn in existence.
Eclipse had his mother's white coat and his father's blue mane and tail. As soon as he was old enough, Celestia started teaching him how to move the sun and the moon. For so many years she felt like she was holding her breath as she waited to see what his cutie mark would be.
When it became what his very name was, an eclipse, she felt the beginnings of hope, but still she waited.
When she saw the signs that he too was ageless, she knew she was almost there as she taught him everything he needed to know about ruling a kingdom.
This morning, he had come to her as excitedly as Luna had come to her all those years ago.
"Mother! I found this interesting prophecy by Starswirl!"
Celestia slowly went over to look at it.
For the sun so loves the moon a prince will become a king. The dark and the light will fall into legend, and the world goes on.
"What does it mean Mother?" Eclipse asked curiously.
Celestia looked at her now adult son. So strong, so handsome, so loving. She loved him too, she did, but not enough to stay. Not enough to keep living with a broken heart that would never fully heal.
It means it's time.
"You'll understand one day."
Later that afternoon she had headed to the cave she had found. It was in the middle of nowhere, in an area that ponies had left abandoned for decades.
"I know how selfish I'm being Luna, but I know now that everything will be okay. The others will be sad, but they'll be all right. They have each other."
Celestia looked at the cave entrance and her horn lit up. Everything shook and rocks started to fall and block the entrance. It shook and shook until it was completely sealed. She could feel the sun going down. She'd asked Eclipse if he wanted to do it tonight, and he had eagerly agreed.
She knew he was going to be a good and just king. She'd taught him well.
She looked back at the picture, at she and Luna standing there in their costumes and beaming for the camera as Luna held up her prize ribbon for winning the contest.
Gradually, Celestia could feel the air in the cave get thinner and thinner as the space ran out of oxygen. She didn't fight it. Didn't fight the drowsiness that steadily overcame her as the light from her horn dimmed and she slowly let go of her hold on the sun, hoping that it would let go of it's hold on her as well. Her eyes closed as she settled further into the comfortable mattress and began to slip into sleep.
She prayed she never woke up.