Taking care of a newborn foal was one thing, even if it were going to be the reincarnation of what might as well be a goddess. But Celestia's "womb" required constant care. Were it not for Spike, Twilight would likely have died from starvation. The only thing that could be done about sleep was the occasional cup of coffee. Celestia needed to be carefully monitored to be sure everything was alright with the strange orb, needed to be supplied with magical energy at least once every three hours, but no more than every half an hour, it needed to be "fed" direct sunlight twice a day, and required "comfort"; Twilight would need to hold the orb occasionally, to simulate the emotion that would be given off of a mare to her unborn child if she were pregnant. It was a long, trying experience, and as much faith as Twilight had in herself, she sometimes wondered to herself if she could do this. She worried constantly about the unborn foal. What will happen if she forgets something? Or if she fell asleep?
This was only made worse by the sudden disappearance of Princess Luna.
Equestria had been thrown into chaos, the government unsure of who would be Luna's successor. Princess Cadence was away tending to the wounds of the Crystal Empire, and it was clear that Prince Blueblood would be unfit for the throne. They needed someone that, Alicorn or not, had the magical prowess to raise and lower the Sun and Moon. It was clear that only Twilight Sparkle, student of the "late" Princess Celestia, would have power anywhere close to strong enough to raise and lower the celestial bodies.
Twilight was rushed to Canterlot, with the womb carefully traveling near her. It was there, for the next two weeks, she underwent extensive magical training, by a sect of mages that had passed their teachings down to the Princesses, the original creators of the spells who had taught Celestia and Luna. Twilight had sworn an oath to never reveal the secrets of the spells required to raise celestial bodies, but as her training progressed, it was clear that she was still not powerful enough to hold dominion over the Sun and Moon. The mages suggested that the other bearers of the Elements of Harmony aid Twilight each day and night, and that their combined power would be able to fuel Twilight's magic, to push the celestial bodies through the day and night sky.
It took some convincing, but Twilight's friends were soon in Canterlot. Fluttershy and Applejack were the hardest to convince to leave their homes; Fluttershy's animals and Applejack's apple trees would need tending to, and with Twilight's extra pull, there were several new ponies arriving at Fluttershy's cottage to care for her animals, and workers were sent to Sweet Apple Acres to help with the harvest.
With their duties sorted, the six Elements of Harmony gathered at the hidden cavern belonging to the Celestial Mages. Celestia's womb was kept in a custom-made saddle-bag over Twilight's flank, always at her side. The mages spoke in a thick accent, unfamiliar to the rest of Equestria. It was clear that they had kept themselves secluded from the rest of the world; Virtually all necessities were found inside their expansive caverns, removing the need to venture out for resources. The eldest Earth Pony, a stallion with a beard touching the ground took a step forward from his brothers and sisters who had formed a circle around the six mares. "Dusk is long over-due. When you are ready, wield the Elements. They will empower Twilight Sparkle, her magic will be strong enough to push the Sun and Moon."
Twilight had been taught that the Sun actually orbits Equestria along with the moon; It is smaller than a normal Star, but Equestria's gravitational pull is too weak to keep them rotating around it in orbit. It had something to do with magic's effect on Equestria, the mages had told Twilight. Celestia and Luna would raise the Sun and Moon to repair their orbit for a limited amount of time. Each day and night, the Sun and Moon would need to be pushed again to keep their orbit in check.
Twilight took her place at the center of the circle created by her friends. Celestia had long ago taught them that multiple formations wielded the elements in different ways. Focusing on the elements, Twilight felt as the other five elements' magical energy flowed into the tiara on her forehead. Twilight casted a spell with her horn, sealing the Elements' surplus magic inside of her body. With a blinding flash of light, their power receded. As the spell's flash of light died down, the ponies looked upon Twilight to see that her horn had extended further, and her hair had grown in length. Twilight took no time in using her new power to lower the Sun with ease, before extending her grip to the Moon and raising it into the sky. At last, for the first time in nearly a day and a half, night had returned.
With the ordeal finally finished, the six mares returned to the Canterlot Castle, where they could take some time to rest and recuperate. Twilight had felt reinvigorated by the Elements' magic, but even so, when she felt the soft, warm bed in her new chambers, the poor, exhausted mare couldn't help but pass out.
Several hours later, Twilight awoke from her much-needed rest. It took her several minutes to realize how much time had past, how long it had been since she had tended to the womb: A whole five hours. In a panicked, frantic state like she had never felt before, Twilight nearly broke down into tears when she could not find the womb. Had someone stolen it? Had Luna staged her disappearance, only to test Twilight's care for Celestia? Did she come in the middle of the night to snatch the womb away, to later scold her for putting Luna's sister in such danger?
It took Twilight an hour of searching, and she found nothing. Twilight collapsed, curling into a ball and sobbing. Whatever had happened to the womb was her fault, and the rage that Luna would show toward her, the fallout that would affect Equestria in the days to come, it would all be on her shoulders. The only comfort came from a small tongue licking Twilight's cheek, soothing the mare's sorrow. "Spike, please, just get out!" She heard a sad sniffle, followed by a saddened wail. Twilight opened her eyes to see a sobbing foal, with a pearl-white coat and soft, pink mane. Twilight thought she had finally snapped, able to do nothing more than reach a hoof out to the foal, to feel its mane, to confirm its presence. Twilight scrambled to her feet, wrapping the frightened foal into her hooves. "There there.. I'm sorry, I was just scared.." She soothed the foal with her voice, rocking the baby back and forth gently in her arms. Twilight tried her best to walk to Spike's bed calmly, still rocking the foal to sleep. "Spike, wake up.. You've got to meet someone." Spike roughly awoke, rubbing his eyes. "Nnghh, what Twilight..? It's finally the middle of the night!-" Twilight pushed a hoof to her mouth to shush him. "We've got to be quiet, the foal is trying to sleep." Spike's eyes went wide with a smile on his face to match. "I-Is that..?" Twilight nodded. "We'll tell the girls in the morning." Spike tickled the foal softly, and Twilight couldn't force herself to stop him as the little foal-Celestia giggled tiredly. "So what are ya gonna name her, Twilight?" She looked at him confusedly. "What do you mean? She's still Celestia, just, well, I mean.." It was clear that a little foal like this would be better fitted to a shorter name. "Celeste. Or Tia for short."
Spike was easily convinced by Twilight to sleep on the couch, to make room for his new sister. Twilight moved the tiny bed carefully closer to her own, so that the foal could be cared for quickly if need be. Twilight started crying again when she finally crawled back to bed. All of her effort had been worth it, and she couldn't have been more proud of herself and Spike.
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The next few days were hard on Twilight, but no worse than the days caring for the womb, and they were made much easier with sleep. The arrival of "Celeste" (Or "Tia" for short) brought forth paperwork, paperwork, and more paperwork. Twilight insisted that she and Spike handle it herself, but welcomed her friends to helping babysit. Each of her friends had a day of the week to babysit Celeste, while Twilight took off time on the weekends to care for her. Fluttershy would bring critters from all around Equestria to amaze Celeste, and would sing her lullabies to help her sleep. Pinkie Pie would play games and throw "Mini-Parties" for her favorite foal princess. Applejack and Rainbow Dash started out making Celeste exercise and have apple-eating contests, but Twilight soon caught on when she came home every day with belly-aches and sore muscles, so that was soon put to rest. Rarity used Celeste to create her own line of clothing for foals and young fillies and colts, and in return played with Celeste and sent home free clothing for her to wear. Twilight was a tad irked when she came home with her hair braided, but came to like Celeste's new hairstyle.
On the weekends, Twilight would invite Rainbow Dash to her chambers, and they would entertain Celeste with feats of flight and magic in an attempt to inspire Celeste use her wings and magic. It often did not bring forth much effort, but Celeste enjoyed it nonetheless, and she would even sometimes make tiny sparks from her horn.
Over the next month, Celeste grew astonishingly fast. She was talking after only two weeks, and near her third week of life, she was calling Twilight "Mommy" after hearing a young filly at the park. She was ludicrously intelligent for her age. Twilight would earn temper tantrums from her adopted daughter if she didn't make the daily tests difficult enough. While her previous incarnation adored cake of all kinds, Celeste had formed an affinity for Cheese-cake of all sorts, shapes, flavors, and recipes.
By three weeks and four days, Celeste's pink mane and tail had both grown a streak of dark purple. The former Celestia's mane had a similar streak of color, but this streak was darker. Twilight came to the conclusion that her new incarnation would not be exactly the same as Celestia in all aspects.
The days went by, Twilight and her friends took care of Celeste, and Twilight Sparkle raised the Sun each day, and the Moon every night. She would bring Celeste with her to watch every time, and her daughter could only stare in awe. "One day, you get to do my job," Twilight would tell her. "I get to raise the Sun and Moon? But.. they look so big, Mommy! Can I really do it?" Twilight nodded and brushed her messy mane back into place with a hoof. "But only if you take a bath every night. No one wants a stinky pants raising their Sun and Moon!" Celeste huffed. She didn't like bathing, but Twilight would give her a new book every day that she was well behaved, and Celeste hated not having a new book around to read.
Celeste was in the tub, Twilight helping her wash behind her ears when she heard Spike in the bedroom. "Twilight, a letter just arrived!" Twilight looked to the bedroom and shouted back. "Just a minute, Spike! I have to go help your brother, but I'll be right back, alright Tia?" She nodded and sat in the bubbly water patiently. Not a moment after she left, the sound of shattering glass could be heard throughout Canterlot. It was louder than anything Celeste had heard, and she nearly slipped under the water when the frightening sound caught her off guard. Twilight came running into the bathroom, scooping Tia out of the tub and quickly drying her off. "Are you okay? Are you hurt?" Celeste was still in shock from the sound. It was like an earthquake, if earthquakes only lasted an instant. Twilight searched for any broken glass, still unsure of what the sound was. She checked Tia over several times for any injuries, but she was in perfect condition. It was obvious the sound had not come from the bathroom.
Twilight went to look out the window, to see chaos in the streets. Ponies everywhere were running, to their homes, to shelter, wherever was off the streets. And in the sky overhead, the Moon had a mark on it's surface, a mare, on the face of the Moon.