> Her Nightlight
>  by BlackWater
> --------------------------------------------------------------------------

> Her Nightlight
> --------------------------------------------------------------------------







Princess Luna knocked softly on her sister's door. It was a big ornate door so much bigger than her that it made her feel smaller than she really was. It didn't help that everything around her was so foreign to her. A thousand years on the moon meant that the world itself was alien, few left-overs from the past to make her feel like it was Equestria at all. In fact, one of the very few things that was the same as before was the pony she now came to see.
It was late at night, after her sister had already said her farewell in lieu of the comfort of sleep. Even the renowned Princess Celestia was mortal in terms of the necessity for rest. But Luna didn't feel much rested herself, for her dramatic return had left her weary and tired. She may have been the Mare of the Night but that routine did not come automatically and she didn't much want routine right now anyways. What she wanted was on the other side of this huge confounded door. Luna was about to knock on it again but then it opened right as her hoof lifted. She placed it back down.
“Lu...?” her elder sister stood there, mane a mess and bags under her eyes. She had clearly been woken up.
“Dearest sister,” Luna began in what was a markedly old way of talking. Far too formal even though it was considered casual in its own day. “Might we intrude upon thy chambers? Thine night barest less mood of comfort than we recollect.”
Celestia should have gotten many awards in her life for things she was unappreciated for, this being just one example. It was a form of mastery how she managed to break through the ancient wording and instantly know what her younger sister was getting at, especially considering how tired and half-asleep she was. Perhaps it was the old memories of her sister that helped make it all intelligible. She never forgot a day she had with Luna, more sharp to her now for the years her sibling had been banished.
Luna entered meekly at her sister's nod of approval. The door was shut behind her while Celestia returned to her bed and slipped under the covers, far too tired to stay on her hooves. But the room was still dark from the elder's previous mode of slumber and the fact that the moonlight was not angling through the windows made the younger sister dart quickly onto the bed.
“Lulu,” Celestia mumbled tiredly as she rested her head back onto her large fluffy pillow. “Is there something wrong with your room? I can have it fixed if-”
“Tis impossible to correct without thy presence,” Luna replied as she too rested on the bed, though atop rather from below the covers.
Celestia sighed wearily. “What renovations could possibly call for more than the castle architects or decorators?”
“Tis not room nor furnishing that we require.”	
“Then what?”
“Tis thy presence,” Luna pursed her lips stubbornly. She pouted a bit, as if it was some indignation for her to have to voice what she did. Yet, she still exuded an air of vulnerability. Proof that the modern world scared her and she wanted to be around the one thing she knew she was safe with.
Celestia had nearly been irritated before about having her few hours of relaxing sleep disturbed, but now she could not find such a feeling anywhere in her heart. It had been replaced by a warm familiarity she had missed painfully for a thousand years.
“You want to sleep in my room tonight?” Celestia smiled even with half-closed eyes and half-asleep mind.
Luna saw it and relaxed more for it. She too smiled. “Slumber hast no room in thine hours now. But thy light and song may bringest our peace.”
Celestia knew for certain now that she was not going to get back to sleep right away, but it didn't bother her as much as it might have otherwise. It had been many centuries since she had given her younger sister a lullaby to sleep to and Luna was obviously bending the truth on not being tired. By some special magic, she found the words and rhythm of one come back to her from times long ago.
The sleepy elder alicorn motioned for her sister to join her under the sheets, which Luna did all too eagerly. The way her small dark form nestled up to her sibling and the way her hooves clutched at her chest started reminisces of their early years when Celestia did this all the time with a pint-sized baby Mare of the Night. Luna even pressed her face into her sister's coat like she did every time she had been frightened by something as a foal.
Celestia fought against her drooping lids to sing the melody, her voice soft and motherly as it had been all those years ago. The lullaby was so old that it predated even Equestria itself and was given very little favors from modern language and rhythm. She sang it all the same to a little sister that knew it well. “Thou tiny hooves I do hold. For now do thee soul I keep.”
Luna made a “hm” sound against Celestia's chest to indicate her comfort.
“Thy heart is safe, thy love is free. Forever in thine hooves thee may sleep.”
Something wet dripped on Celestia's chest. It was hard to look down without disturbing her sister, but she managed somehow and found Luna teary around the corners of her eyes. But her lids were closed and her breathing steady. Not had even a quarter of the lullaby been sang before Luna had drifted off. Celestia never remembered her sister so quick to slumber before. This and some other things made her wonder.
Being very tired herself, barely having been able to stay awake for Luna's sake, the Mare of the Sun fell into the darkness of sleep. There were no nightmares that night save the harmless one nestled in her hooves.









Princess Celestia awoke the next morning before dawn as she always did in order to raise the sun. She thus awoke to find Luna cuddled against her. It took her a while laying in bed to remember why her sister was with her. In fact, it took a moment to fully realize this was not a dream and that her sister really had returned from the moon and reunited with her. She had experienced dreams in the past like this, where Luna had returned and lived with her just like those past millennia.
All the emotions she hadn't felt the day before came at her like a typhoon and she had to try very hard not to breakdown. She had many things to do today as she always did, so there was no time for her to spend on crying like a foal. But, in spite of her many years, she was not dead to emotion and it took much to hold together. It took this moment, waking up to her baby sister in her hooves, to remember how much weight her last living relative held with her.
She wiped her face on the pillow and got up cautiously so as not to wake Luna, who she settled back into the sheets with care. There was a grand balcony she started towards that attached directly to her bedroom, which was normally curtained off to prevent prying eyes. Celestia never thought it made much sense to worry since it faced the castle's secluded inner garden, which only a few servants ever went through anyways. She only kept the curtains because she rather liked them. Deep burgundy. It was a nice color to offset so many other things in the castle that were struck in light and airy hues.
The heavy curtains were drawn by her magic to reveal the dark morning beyond. Celestia proceeded to open the glass balcony doors and stepped through them. While most ponies reveled in the warm air of the day, Celestia adored the cool misty air of pre-morning. It was so refreshing but also very short-lived. It only happened after the dew and before the sunrise, which the white mare breathed in as she stepped onto the equally cool stone of the balcony.
Judging only from the balcony, it was unclear exactly how many stories up she was, but it had to be at least five. It was a perfect unobstructed view to the garden below, filled with neatly kept hedges, flowers, and even a few trees. There was one servant about, making sure the princess' cushion along the cobblestone path at the center was flawlessly prepared for whatever whim the royal might have for respite. Being the time that it was, the servant mare looked up to the balcony and waved politely. Celestia waved in return with a smile.
The sun. It was laying just over the horizon, hidden both by the crest of the land and by the castle walls and towers that rested before it. Celestia looked up to the same spot between two spires that she did every single day. That was where the orb of fire would rise from and, indeed, that was where it rose from today. The alicorn sighed lightly as she rose her front hooves up from the balcony floor. With the hooves, the sun arose from its sleep and began bathing the land in a soft yellow glow. Henceforth would it tick along its cycle until the end of the day when Celestia would bid it good night once more.
Two long and slender hooves tapped back down onto the stone floor that was already starting to heat up from the orb's rays. It was a groan from behind her that made Celestia turn leisurely around and peer into the room at her sister. She was on the bed still and under the covers completely. Only her starry mane stuck out onto the pillow, where it laid frazzled by the night's sleep.
Celestia smiled again, this time more truly. Would she get to keep living this dream every day? Keep seeing her little Luna alive and safe with her? The fire that had kindled in her before, as strong as her very own sun, became clearer now. Perhaps it was everything she and Luna had gone through for millennia after millennia or maybe it was the immeasurable pain of being the last of her family, a pain removed by Luna's return. In any case, Celestia was truly happy again and nothing would or even could take that away from her.
The tall mare trotted back into her room with a bounce she hadn't had in far too long. The glass doors closed behind her but the curtains did not. Over to her vanity dresser she went, where she could begin taming the wild multi-hued mane of hers. Few ponies ever saw it like this and thus few ever realized how utterly impossible it would normally be to reign in such a large and magical mane and tail. 
As she brushed it, the colors started moving in more serene patterns, contrast to the chaotic ones they danced to amidst the frizz. With luck, this would be another morning in which she did not snag a knot and accidentally unleash a ten millionth fraction of the mane's eternal magic. The last time had released a flare of six thousand kloven degrees. She had to get the entire bedroom renovated, which was actually not too difficult considering the fact that everything in it had been reduced to mere ash. Right down to the stone under the thick carpet and decorative wooden walls.
“Mmngh,” moaned Luna from beneath the plush sheets.
“What was that, Lulu?” Celestia asked in a chipper mood. With her expertise and extensive use of magic, the mane was already half under control.
“We desire darkness,” the smaller alicorn mumbled sleepily from beneath the covers.
The elder sister glanced over to the bed and couldn't help wondering. “How in the greater universe could it not be dark under there?”
“Thy light,” Luna continued to sound muffled from her hiding place. “It seeps through!”
Celestia giggled as she finished her mane. Now for the tail. “I'm sorry, sister, but it's shaping up to be such a wonderful day. Why don't you come out? We can have breakfast in the garden.”
There was some murmur from the bed sheets, but it was too garbled to understand.
“We'll have coffee cake and that tea the staff makes – I forget what it's called. It's good on the stomach so early,” Celestia went on. “I know I shouldn't go straight to the cake after waking up but I just can't-”
Another murmur came from the bed, this one louder and grumpier than the last.
Celestia finished taming her tail, set the brush on the desk, and then tapped a forehoof to her chin. She needed something to get her sister up. “I know,” she finally thought in a light bulb moment. “How about I personally make some dark chocolate breakfast danishes? The ones with the star sprinkles and the cutout of the moon in the center?”
Luna shot out from the bed like a Bengal tiger upon an injured gazelle. The sheets flew off the opposite side of the bed and the dark alicorn's hooves were wrapped around her sister's neck. “Thou wouldst makest them?” she beamed the same way she had as a tiny filly. “For us?!”
“Of course, Lulu,” Celestia giggled. “I didn't mention anypony else, did I?”
“We adorest thee!” Luna sang as she nuzzled her elder sister's neck.
The words burned in Celestia's heart. It was just like when they were young, before they were princesses and the world was not between them. These pastries would be the best she had ever made.









As it turned out, the best pastries she had ever made only came after the fourth failure. Celestia's patience was wearing thin for once and only the random success gave her back a measure of calmness. The kitchen staff very much appreciated this because they worried that the flames that started emanating from the immortal alicorn might proceed to burn the place down. The flames receded and all was well.
A few of the chefs discussed how thankful they were for their jobs after she left - that their work meant keeping their ruler from igniting half of Canterlot over a few simple pastries. The lead chef promised himself that he would be far more adamant next time about convincing the princess that he would make whatever she desired. Why she was so intent on doing it herself this time was beyond him.
Celestia bounced along outside of the kitchen, in the hallway leading to the garden. She didn't spring quite like Twilight's friend Pinkie Pie but she still skipped along in a manner than none had seen for several generations at least. Only a few of the castle staff saw her go by at all.
The glass doors eased open on their well oiled hinges by way of Celestia's pale yellow magic. She trotted down a few steps after the doors and made her way across the cobblestone path to her target destination. The sun was still young in the sky, the air fresh and cool, and the garden wildlife making a beautiful chorus of noise. When she rounded the last turn to behold her little sister seated at a picnic blanket off the side of the path, she stopped.
The pastries wavered in her levitational aura, which weakened upon an onslaught of emotion. Celestia's face twitched but then straightened back into a smile. She continued forward just as her sister noticed her coming. She had to walk carefully past some of the garden's rare purple and scarlet roses until her hooves were safely on the black and white of the blanket. It was decorated with black suns and white moons in contemporary artistic style.
Luna was already laying down in a pert position and so Celestia copied her as she lowered the pastries down before her sister, settling them onto a plush black napkin as she did so. She wouldn't and couldn't ever forget the slightly widened eyes of her sibling, her unfettered glee, or the way her mouth already began salivating.
“Tia!” Luna jumped from her spot straight over the pastries. It honestly surprised the elder sister how Luna simply hugged her like a vice grip.
“Goodness,” Celestia returned the hug with far less grip, though no less enthusiasm. “They're just pastries. You don't need to get so-”
“Pastries? Pastries?!” Luna leaned back and balked. “We remembered them, Tia. We've waited a thousand years to partake of them again.”
Celestia began to think that Luna was not so interested in the food as she was in the fact that it was her sister who made them. She used to make them all the time in the distant past, even if she had perhaps fallen a bit out of practice of late. In any case, it was something that was just between the two of them. 
“Well maybe you should try one then,” the white mare pushed her sister back towards the subject material.
Luna rolled over playfully towards them and grabbed one with her magic. She broke it in half, dark chocolate oozing from the inside. She bit into one and levitated the other to Celestia, who shook her head with a smile as she relented to her sister's sharing. She too bit in and savored it.
“Mm!” Luna sparked with joy at the taste.
Celestia closed her eyes for a moment as she enjoyed the flavor as well. It was nice but she didn't have half the passion her sister did for the taste of dark chocolate and soft pastry. Cake was more her style.
After that, Luna ripped through the remaining three and even forgot to give Celestia a half of one in her rush to devour them. The napkin wound up well used, a casualty in the war to keep the smaller alicorn's face clean from chocolate drizzles.
“Maybe you should have gotten the sun for your cutie mark with the way you burn through those,” Celestia poked her sister in fun.
“Thou may,” Luna garbled with her cheeks still full with the last one, “jest at thy own risk.”
“How about we go diving today?” Celestia switched tracks. “We can play around in the cavern pool.”
Luna was intrigued at the idea but also surprised that her sister would suggest it. “Does court not deter thou holiday?”
The elder mare almost pounded her face into the ground. Luna's speech was so thickly ancient that one would need a triple bypass to save it. “No, Lulu,” she replied in patience. “Court never ends and I consider my time with you far more important than it.”
“Tis more enjoyable?” the younger princess asked with wavering eyes the size of dinner plates.
Celestia reached out and ruffled her sister's mane, which Luna scrunched her face up in annoyance to. “That goes without saying. I'd have to be delirious to find court interesting in the slightest. There hasn't even been a new case for two and a half centuries. It's always the same trouble. Just different names and faces.”
“We see it has not changed then,” Luna remarked as she attempted smoothing her mane back out.
“No,” Celestia agreed, “but the pool has. A thousand years has given the cave time to erode. It's deeper.”
“By what measurement?”
“It's very deep,” the white mare repeated vaguely but with a spooky voice.
“Tia,” Luna spoke more softly now. “We are app-”
Celestia stopped her by placing her hoof over her mouth. It lacked the royal shoe because she intentionally hadn't put them on earlier. “Don't thank me.”









“Tis difficult to see,” Luna commented as they walked through the dark cavern tunnel. She was fiddling with her sack of supplies she had brought along because the bulk of it was too unwieldy to carry on her back. She had to levitate it along in a deep purple magical grip. As for her traversing the cavern itself, it seemed a little different from the last time she had been through it with her sister.
“I've tried to keep it natural, so I didn't put up many lights,” Celestia explained. “It may be difficult to get through if you don't know it well enough. But, then, that's why I'm here,” she turned her head and winked at Luna.
The other alicorn just rolled her eyes. “We hope thou hast lead us for more than the sake of leading. We are to both dive to the bottom, yes?”
Celestia returned her attention to the path ahead since even she had to squint and concentrate not to get lost. She did not, of course, mention that to Luna. Her passive older sister instincts always told her not to worry her younger sister. “Indeed, we will brave new depths and etch your name upon them!”
She had tried going the “adventure voice” route but she wound up sounding nothing more than ridiculous. It did, however, make Luna giggle and that was worth more than all the gems in Equestria. Luna did, after all, rarely giggle even before they drifted apart in the past.
The dank air of the underground place didn't bother either of them, though Luna did find the occasionally wet stone of the floor to feel different. It had been literally ages since she had touched hoof in a cave and this one was simply dripping. The only reason she could see at all to follow her sister was the fact that Celestia had a little light twinkling at the tip of her horn. She often did that when she was leading Luna through some place dark. Over their thousands of years, they had the opportunity to have many such instances.
The light soothed her and she avoided any mention that her vision in the dark was far better than her sister's. Being the Mare of the Moon meant she had exceptional night vision, but she pretended to rely on her sister instead merely because she wanted to. She felt the whole situation was too good to be true, what with her sister accepting and forgiving her so completely. If she could eek out any more from this living dream then she would do so.
There was also the faint and unreliable light from the surface that seeped through deep cracks in the cavern ceiling. They were traversing a relatively short part of the cave system that led from the garden's secret entrance to the diving pool. As Celestia had indicated, there were very few lanterns along the way and none of them were lit. Only when they arrived in the chamber containing the pool did the elder sister light the single magical lantern hanging up in the middle of the ceiling.
The place had a slope to it that she could now see by the lantern's glow. It led down into the still water of the pool and she could even see the disappearing depth as it receded further and further down. That part she remembered from before but it seemed too much the same and too smooth to be something that had naturally stayed that way for over a thousand years.
The air of the chamber was heavy because of the water but the pool, even in the center, was still crystal clear. A subtle mist rose from the surface to indicate it was warmer than the temperature above, which Luna confirmed as she touched the water's edge with a forehoof. With the relaxing twilight glow spread about the chamber and the welcoming pool, this was looking to be a pleasant venture.
Celestia dumped her own bag of equipment on the stone slope leading down into the depths, right before the water began. She made for light conversation over the drip drip noise that seemed to persist in all damp caves. Luna followed her example and opened her bag.
“There have been so many inventions in the last millennium. Especially lately,” Celestia went on as she stretched out one item she had retrieved from her bag. It was a large suit that fit her unusual stature, but it was skintight. The white color matched her coat except for the yellow and orange highlights that struck across it, nearly glowing in the dark. “This one pegasus, Oxygen Rush, invented these suits because she wanted to explore what she called the 'other sky.' So many pegasus spend their lives in the sky but she was fascinated by the ocean. Her special talent turned out to be something new entirely – making underwater exploration equipment.”
“Curious,” Luna responded simply as she stared at her own suit she levitated in front of her. It was of a beautiful black and dark purple with stars decorating it in conservative patterns that came off as more artistic than overwhelming. The stars themselves shimmered. But how did it go on?
Celestia was already half into hers and was using her magic to ease into the upper half. “She eventually made a living out of it and created H2pOny, the company that made these suits.”
“We have dived without them,” Luna was ready to give up on figuring out how to get into it. “How might these help?”
“Oh,” Celestia flipped her hoof playfully. “They just make it a little easier. I'd give you the full explanation I got from Oxygen Rush herself but I doubt you'd find it interesting. Anyhow...”
Poof!
Luna straightened in posture suddenly. A near-white flash of magic had taken the suit from her grip and instantly equipped it upon her body. It was the most disturbing sensation she had experienced in a very long while because it was indeed a skin-tight piece of apparel.
“Normal ponies also use things like goggles and oxygen tanks but I opted to use the suits alone and use magic for the rest. It'll be fun, Lulu.”
“W-we're beginning to question,” the dark alicorn stuttered from her earlier surprise. She took a tentative step towards the water. “We also do not recall what magic thou refers to.”
“I wouldn't think so,” Celestia said as she too approached the shallow start of the pool. She put both forehooves in and found it as pleasantly warm as she remembered. Being underground and away from most light, it could only be an underground spring or volcanic vent that heated it. “I came up with oxygen conversion and increased underwater visibility spells only a few hundred years ago. Tricky stuff, you know?”
“We trust thou willst share?” Luna guessed.
At that, the elder wadded through the fetlock-high water to her sister and patted her on the head. “Of course, Lulu.”
Another less invasive flash of Celestia's magic applied the appropriate spells. Luna found herself struck with a new feeling she hadn't felt seemingly in eons. It was almost as if she felt giddy. Perhaps that was why she started stepping down into deeper water, eager to try this new magic of her sister's. 
The pool now began to receive the ripples from the eight hooves of the two princesses and sent echoes of the moving water up to the ceiling and walls. The lantern cast down a homely orange light that was dim but pierced the surface of the pool and revealed enough of what was below to prevent fear thereof. 
Once Luna was far enough so that the water began tapping her underside, she leaned down and stuck her face experimentally into the liquid. She was a bit scared to do it but still mustered the courage to open her eyes beneath the surface. Instead of getting a mild sting and seeing murkily, she felt no different than if she had opened her eyes above the water and her vision was crystal clear. She flung her head back up and tossed water all about because of her wet starry mane.
“Tia, tis incredible!” she shouted with glee.
Celestia, however, was already on her back and doing a butterfly stroke further into the pool. “I know,” she agreed without humility and with a content little smile.
“We must traverse to the bottom!” Luna enthused even more as she darted for the deep center that lead straight down.
The elder sister raised a brow and flipped around so that she began diving as well. She wasn't about to let Luna get lost. At least not so quickly. Breathing and seeing underwater only went so far when there was no light further down. She immediately lit her horn again with her beacon magic, stronger this time to illuminate more.
Luna latched onto the light and swam to it until they were both in front of each other, suspended in the water's realm. She was wondering how they were going to talk when her sister did just that. A few bubbles came out of her mouth and drifted to the surface, but her voice was otherwise clear.
“I also came up with a way to talk,” Celestia exclaimed. “It took another fifty years but I'm patient.”
Luna laughed with a hoof subconsciously going to her mouth. She had a habit of doing that.
“I'm surprised you still know how to get around underwater,” Celestia continued unabated. “Sure you don't need me to hold your hoof?”
“Hmph,” Luna pursed her lips and puffed her cheeks. She was just so easy to tease sometimes.
The elder mare couldn't help but to suggest a race. “Why don't we see how far we can go before you tire out?”
“Thou hast proposed a challenge?” Luna turned her nose up as acceptance. She seemed awfully confident about it.
“Give me a reason to worry about my reputation,” Celestia countered. 
There was a moments silence and a decrease in bubbles escaping their mouths until it was officially on. Celestia was the first to dart down and Luna played dirty by grabbing her back hooves. The elder sibling jerked back as Luna propelled past her like a bullet into the darkness. Celestia cursed at how much her sister remembered from before her imprisonment. It was as if she had been swimming non-stop on the moon, which was obviously ridiculous.
The Mare of the Sun decided to use her trump card right from the start and immediately the water around her heated up. Her mane burned with a fire that mixed magically with the water, giving her unlimited energy. She stretched a foreleg forward and shot towards the bottom at record speed.
“Later,” Celestia pipped as she passed by her sister and continued rocketing to the bottom, which was still a long ways down.
Meanwhile, Luna stared in astonishment. Celestia was already good at so many things. Wasn't being better than her at seemingly everything else good enough for her elder sister? Did diving have to be one more thing she outshone her in? But she could see Celestia's glowing horn tip receding into the dark waters below and she began to panic, all sibling comparisons forgotten. Without that light, she was scared. It was not so much a matter of seeing or lighting her own way as it was being alone again in the dark.
With her panic, Luna found a new burst of speed that even Celestia in all of her years of additional experience could not hold out against. About two hundred hooves deeper, the elder mare felt something tackle her from behind, wrapping hooves around her midsection between her body and wings. The weight pulled her back and slowed her down.
“Wha-?” Celestia floundered to a stop, nearly colliding with the cliff-like wall of the underwater realm. She wriggled around to see what had grabbed her. Not surprised at the answer, she begged the question. “What's wrong, Lulu?”
Luna's face was buried into Celestia's side but she mumbled an answer anyways. The sensation of the oxygen bubbles escaping against her coat made Celestia stifle a ticklish laugh. She had never actually done this kind of underwater activity with anypony else.
“We yield,” Luna answered. “Thou ability is greater.” 
There was something in the dark alicorn's voice that concerned Celestia. “Certainly not,” she argued. “I merely cheated by using a spell I didn't tell you about. Why are you still clutching me?”
“We fear we do not like this place anymore,” Luna finally looked up at her sister from her spot against her left wing.
The elder sister looked this way and that. Nothing about the underwater chasm made her think that it would be particularly unlikable. It was dark, yes, but there was enough light from her horn to see a good fifty hooves and the place was really without much feature. Above there was darkness that would eventually break for the light of the surface and below there was also darkness that would eventually break for the simple end that came at the bottom. The walls were not overly rough but kept smooth enough to make one wonder if it really had been formed by the natural deterioration of water.
“Why do you fear it?” Celestia finally asked at a loss. She turned and held her sister in her hooves.
“It reminds us,” Luna replied, “of our moon. We saw thouest leaving us...again.”
“Oh, Lulu,” Celestia frowned and hugged her sister close. “That'll never happen again. I promise you.”
Luna never stopped clutching her. After a moment, she continued. 
“Perhaps we should just swim down together. No more racing.”
“We agree.”
With that, the two of them resumed their adventurous deep water diving, Celestia's magic working hard behind the scenes to accommodate the increased pressure and oxygen conversion. This time, however, they swam at a leisurely pace down to the end. Luna held one of her sister's forehooves and never let go.









The bottom was far less climatic than Luna had predicted. For the most part it was just a half-smooth floor with a few scattered cracks and crags leading into the earth below. Warmth radiated from these spot but all were far too small to get into. They spent some time there playing about with no clear goal in mind. Play was never in need of complex objective or intricate strategy, especially when it involved seeing which one of them could jump further from the floor.
It was a good hour later when they emerged back at the pool's surface that Celestia realized they had, in fact, been down there that long. How long, in turn, had it been since she had lost her concept of time? How long had it been since she had fun without having to plan for a thousand contingencies?
Luna was beaming like a filly again, her soaked form and wet mane dripping in the somber light of the chamber's ceiling lantern and Celestia's own magical light that had yet to diminish. Luna seemed to like having it and so the mare kept it aglow. It took very little effort to do so anyways.
Celestia herself was in no better position, dripping about as she waded out of the fetlock-high water. Her mane and tail were drooping like curtains and would make her hardly recognizable to most of her subjects who never saw her with anything but her usual light and waving style. She knew how to fix herself, though.
For a fraction of a second, the chamber was flooded by an intense red and orange light of fire as the white Mare of the Sun was engulfed in her eternal flames. Once the second was passed, she stood there refreshed to her usual state, mane flowing and not a single droop of water on her entire body. A little steam drifted off of her along with a thin layer of smoke from the flames.
“Oh,” Celestia caught herself and mimicked her sister by raising a forehoof in front of her mouth.
Luna was staring open-mouthed. She was still in her waterlogged form, dripping about the cave floor with the water drifting down the gentle slope to return to the pool. She did not have such drying magic herself and scarcely remembered her sister using it either.
“It's funny,” Celestia commented and placed her hoof back down. “I could always do that. I just never thought of it.”
“Dry us,” Luna closed her mouth and ordered with a serious expression.
“Hm,” Celestia mused and trotted further away from the water. “Or else what?”
“Tia...” Luna said huskily as a warning.
“Aren't we a little needy today?” the elder sister laughed as she started getting more distant from her sibling.
“We desire thy unwateryness!” Luna exclaimed as she darted to Celestia.
“No, Lulu,” the white alicorn went white-eyed. If Luna got too close than she might get wet again and she had no wish to repeat her magic endlessly to stay dry. With that horrific possibility in mind, she started taking off down the tunnel.
The Mare of the Moon was in hot pursuit, water flicking this way and that as her voluminous starry mane waved behind her in a heavy clump. She hadn't even the time to take off her diving suit but then Celestia hadn't done so either.
Not once did Luna lose sight of her. She was giving all of herself to keep up, all the while not knowing that her sister was intentionally slowing her pace to remain close. Celestia wasn't about to repeat what happened in the pool, but she could still keep her fun.
The elder alicorn almost tripped when she came around the last turn to the cave entrance. It opened up back to the inner garden and the day had come along enough for the late morning light to be blinding. The faint indirect light that seeped through the cracks along the cavern passages was nothing in comparison. Even Celestia was blinded for a fraction of a second and it was long enough for somepony to crash into her from behind.
Luna landed on Celestia's back with a thump. The slickness of her wet diving suit started her farther forward than she intended and she fought to keep herself from flipping over. The larger mare couldn't compensate fast enough and they both wound up tumbling head over hoof out of the moss and vine-covered entrance. They rolled through the grass off the side of the cobblestone path and thankfully came to a halt before plowing down the red and orange summer flowers.
The world stopped spinning and Celestia found a stability to her vision. She was laying down with her back into the fresh grass and soft soil with Luna sprawled out on her belly. Now she was both wet and dirty. 
“Brilliant,” she commented dryly.
“We are fine,” her sister said more level-headed.
“Are you referring to the both of us or just yourself?” Celestia deadpanned.
Luna was silent for a full five seconds before she started giggling. Celestia joined in before shoving Luna off of her. She got to her hooves and swung out her massive wings, sprinkling dirt about. She had planned a bath after the dive but hadn't anticipated needing it quite so badly.
“We are hungry,” Luna began anew as she also got to her hooves and looked sadly at her muddy mane. “Feed us.”
“Now you're just messing with me,” Celestia grinned.
The smaller mare started back down the path to the castle doors, ignoring the remark that was entirely true. She wasn't about to let her sister have all of the fun. “Tis the time for the midday meal. We shall partake of it whilst in the royal bath.”
“You mean my royal bath,” Celestia trotted up to Luna's side in sudden urgency. “That I will be using first.”
“Thou hast less need of it. Our mane has been marred by mud, dear sister.”
“Which wouldn't have happened if you hadn't chased me through the caves like a filly on her birthday,” the elder argued. “My wings are just as dirty. Do you have any idea how long it takes to get so many feathers in order?”
Luna sighed as they entered and walked through the castle up to Celestia's grand bedroom. “We admit we do not. Our wings are of less volume, but certainly not of less quality. We intend to take care of them just as well.”
“Anyway, it's my bath,” Celestia grasped for her chance to be first. “You have your own. So go use it.”
“The one adjoined to our bedroom?” Luna gawked. “Tis unusable. There are cobwebs in the tub!”
“The servants haven't fixed it?” Celestia now said more to herself than her sister. 
She hardly even noticed they had passed into her bedroom and then into her bathroom. It was quite the ornate establishment, with gold decorations and intricate lamps casting moody light upon every corner that was lost in the brightness of the midday hour. The bathtub itself took up a good quarter of the large room, set into the floor and built more like a spa or hot tub than any simple cleaning basin.
Luna stopped in her tracks as she came to the side of the tub, turning a decorative sun-shaped handle to get the hot water flowing. She practically swiveled in place to face her sister point blank. 
“We will be as brief as possible,” she encouraged, “so thou hast time also to clean before the day is done. Order the servants to bring us something to eat.”
Celestia held back no longer. She laughed loud and hard. By the confused look her younger sister gave her, it was difficult to tell how much had been a joke and how much had been real.
“We missed some humor?” Luna looked this way and that for some lost joke.
At last, Celestia finished her bout and stepped into the accumulating water in the tub to test it. It was far warmer than that of the diving pool. Just the way she liked it. With reckless abandon, she used a flash of magic to remove both her and her sister's suits and discarded them into the hamper in the far corner of the room. She then stepped fully into the tub.
“It's far bigger than the two of us,” she shook her head. “We can wash at the same time and,” she gestured to a rope hanging from the ceiling near one of the tub's edges, “I can call for something to eat right here.”









Not once did Celestia go to court that day. She found it so enjoyable to spend hour after hour with her returned sister that she even entertained the thought of forgetting ever going back at all. But it was just a fleeting absurdity and she decided it was best to return to it the next morning. But, since today was not yet upon her, she wasn't going to worry about it any more than she already had.
Luna was hesitant at first to share the tub with her sibling, though there really was nothing at all peculiar about it. More than anything else, she merely feared her older sister would judge some way in which she cleaned her coat or wing feathers and voice such opinion. The sense of approval was something she struggled with.
Still, the washing went without incident minus Celestia's endless pampering of her sister. She couldn't help remarking that having seasoned butter biscuits in the bath was something she had never done before, which was really saying a lot due to their age. They were dry in short order thanks to the elder's continued use of her drying magic, which was not withheld this time.
It was later on, after they had exhausted a good number of the various venues of entertainment in the castle, that Celestia flopped down upon her bed once again. Looking back, she couldn't say she had really done anything the whole day. Goofing off with her sister, though, had somehow managed to sap her of her energy in a good way. It had been forever since she had felt this tired and this fulfilled.
Luna flopped down beside her on the massive bed. “We are thankful for it,” she commented openly.
“For what?” Celestia said within a yawn, sprawled out and enjoying the softness of the plush sheets.
The Princess of the Night crawled over and rested her head against her sister's side. “For not being alone anymore,” she replied in contentment.
“Lulu,” Celestia whispered. “You'll never be alone again. I promise.”
“Thank you, Tia,” Luna smiled with her eyes closed. The sun, set gently by the elder mare, was now barely a glow coming in through the open balcony door and the night's cool air was beginning to drift in. “Thou should know, of all the stars we put in the sky, none come close to the one we treasure most.”
“Which one is that?” Celestia inquired as she watched nightfall descend.
“The star on the tip of thy horn. The one thouest shone every night for us when we were frightened.”
“Lulu,” Celestia whispered through her teary joy, “I'll always be your nightlight.”
“May we sleep here then?”
“Whenever you want to,” Celestia smiled, more grateful than she ever had been in her life to have her family back.