“And now, fillies and gentlecolts, it is my honor and pleasure to introduce our special guest this evening—the guardian of the night, protector of our dreams, and gracious ruler of our land, Princess Luna!”
The crowd roared with approval as Luna emerged from behind the curtain, and grew louder with each step across the stage towards the podium. The mass of good feelings between thrown Luna's way made her eyes light up and brought a small smile to her lips, but she quickly suppressed her feelings to maintain her royal decorum and only acknowledged the crowd with a small, polite wave of her hoof.
Luna stepped up to the podium, but before she began speaking, she took a moment to look out at the crowd gathered before her. The sight was like nothing she had ever seen before. Thousands of ponies of different shapes and sizes were looking back at her, all smiling and cheering and yelling words of encouragement. This was the moment Luna had been waiting for her entire life. These ponies had all come to see her this evening not out of fear or blind respect for her position, but because they truly appreciated her. They were here not to celebrate a princess, but to express their love and affection for a cherished friend.
Luna felt her heart swell with happiness, and could no longer contain her emotions. “Thank you, everypony!” she sang into the microphone, as a large smile creased her face. “We are humbled by your gracious welcome, and pleased to be here for tonight's Lunar Celebration! And now, for the moment you all have been waiting for!”
As the crowd continued to cheer, Luna spread her wings wide and summoned her magic, causing a bright blue aura to surround her horn. She bent her knees slightly, then leaped into the air, raising her front hooves skyward and flapping her wings to ascend into the sky.
As Luna floated up from the stage, the moon began to peek over the horizon behind her. Both moon and pony rose up as one, as the sky darkened to reveal a veritable fireworks display of stars. The crowd, bedazzled by the production, stared up at Luna for a few moments in a collective stunned silence, then erupted into another round of cheers.
Looking down at the crowd, Luna smiled and allowed the sights and sounds of the scene to wash over her: The stars above, the adoring masses below, the sound of bells ringing in the—wait, she recognized those bells...
“NO!!!” Luna screamed, sitting up in her bed with a start. She sat in stunned silence for a few moments, her eyes wide, her mouth hung open, and her hooves trembling, as she processed her sudden change of scenery. Instead of being on stage before an adoring crowd, she found herself lying on her bed in the middle of her cluttered room, with her shades drawn and curtain closed to keep the sun from peeking in. The moon and stars above her had disappeared, replaced by a static mural on her ceiling that some unenlightened foal had painted by throwing small white specs around the scene without regard for proper astrological structure. The cheers had vanished as well, but the bells still tolled, emanating from a grandfather clock standing in the corner of the room.
“NO!!!” Luna repeated, punctuating the word by slamming her front hooves on the bed. She scowled at the clock, then reached back and pinched her pillow between her hooves. Lifting the pillow over her head, Luna summoned all her strength and flung the pillow towards the clock, where it bounced harmlessly off the pendulum tower.
Unsatisfied with the clock's unflinching reaction, Luna decided to make the device pay its proper penance for rudely interrupting the first pleasant dream she had experienced in months. Luna's horn again began to glow, causing a bright blue aura to surround the clock's pendulum. With a sharp jerk of her head, Luna ripped the pendulum out of the clock, shattering the glass in the front of the tower in the process. As an angry snarl appeared on Luna's face, the princess proceeded to use the pendulum as a sledgehammer, smashing the clock over and over until it was nothing but a pile of gears and splinters on the floor.
As Luna landed her final few blows, the anger finally began to drain from her body, and the scowl on her face receded to a blank, emotionless stare. Dropping the pendulum onto the floor, she sighed as she gazed upon her destructive handiwork. This was not the first household item to suffer Luna's early-evening wrath, but it was easily the most expensive, and she was sure to get a long lecture from her sister about controlling her temper.
As she re-summoned her magic to pick up the pieces of her clock and drop them into the trash, she realized that she had forgotten to check the time on the clock before destroying it. Luckily, the castle clock tower was visible from her front window, and while she hated to open her bedroom to the light—it reminded her just her messy and dusty her room actually was—she knew that desperate times called for desperate measures.
Luna walked over to the window and used her magic to draw the curtains back, squinting her eyes at the bright, beautiful scene that greeted her. The low angle of the sun in the sky had created a spectacular red sky over the capital city of Canterlot. Only a few stray ponies were around to appreciate the view, however, as most had already wrapped up their daily activities and made their way back to their homes and families.
Luna grimaced at the peaceful silence that now enveloped Canterlot, knowing full well that even fewer ponies would be out and about to witness her raising of the moon and bringing of the night. Once again, her serene-yet-stunning creation would be met with crickets from the rest of the world, just like yesterday, and the day before that, and the thousand years before that...
Luna quickly glanced up at the castle clock tower, noted that the time was a few minutes past seven, and pulled the curtains together to hide the scene from her eyes. Turning away from the window, Luna took a deep breath and told herself to maintain her focus and forget about the rest of the world. She had a long night's work ahead of her, and moping about how few ponies would actually notice her efforts would not get her job done any faster.
It was the same old morning routine for Luna. First, a quick shower to wash away the remnants of yesterday. Next, a thorough combing of her hair to get her dark-blue, star-studded mane and tail under control. She concluded with just enough brushing of her teeth to keep her sister from complaining about her breath and lecturing her about proper dental habits. As she rinsed the toothpaste from her mouth, she wondered why she even bothered with all this work. Nopony was going to see her anyway.
After finishing her morning ritual, she made her way to the castle dining room for her usual bowl of Frosted Flakes. Her sister, Princess Celestia, who watched over Equestria during the day, was already at the table when Luna arrived. "Good evening, sister," Celestia greeted Luna in between bites of her wheatgrass sandwich.
"Good evening," Luna replied monotonically, still not fully awake. "Dost thou have anything to report?"
"It's 'do you have anything to report,'" Celestia corrected. "You're trying to work on your word choice, remember?"
"Thou hast—I mean, you have not answered our question," Luna mumbled, using her magic to pour herself a bowl of cereal.
"'My' question," Celestia answered. "But no, nothing to report today."
"Good. Then we—I suspect that this will be an uneventful evening." Luna took a bite of her cereal, once again noting that it was never as 'grrrrreat' as the tiger on the box promised.
The princesses sat and ate in an awkward silence for a few minutes. "You know," Celestia finally spoke, "Trottingham held their annual summer festival today."
"Marvelous," Luna muttered, not bothering to look up from her breakfast.
"It was lovely," Celestia went on. "There was a parade, and a competition for the best-looking flower garden, and a seven-legged race for the foals—"
"I'm sure it was breathtaking," Luna interrupted. "Perhaps we will—I'll get to see it the next time they hold the festival at midnight."
Celestia set her sandwich down and stared silently over at her sister. While Luna did not bother to meet her sister's gaze, she could feel Celestia's eyes burning holes through her coat, which irritated her to no end. After several awkward seconds, Luna muttered something under her breath and looked up to meet Celestia's gaze. "Yes?"
"Are you feeling okay?" Celestia asked. "Would you like to talk about anything?"
"No, no," Luna declined as she rubbed her eyes and feigned a yawn. "I did not sleep well; that is all."
"I see." Celestia nodded to acknowledge the answer, but she maintained her suspicious stare for a few more seconds before going back to her breakfast. She quickly finished the last few bites of her sandwich and stood up from the table. "Shall we?" she asked.
Luna sighed. "I suppose." She stood up from the table and followed Celestia onto the balcony adjacent to their dining room. "After you."
Celestia nodded, then summoned her magic and slowly lowered the sun out of the sky, hiding it below the horizon. In response, Luna used her own magic to bring her moon out from behind the far-off mountains, placing it low in the eastern sky.
"Is that where the moon should be?" Celestia questioned. "It seems a bit high for this time of night."
"It is close enough," Luna replied curtly. "Nopony is looking at the moon anyway." She placed her front hooves on the balcony railing and spread her wings. "We—I believe I shall make my rounds early this evening."
"Perhaps you could stay inside a while longer," Celestia suggested. "We could sit by the castle fireplace and" — She looked back towards the castle. — "discuss things."
"No," Luna declared. "You must rest for tomorrow. Besides, there is as little to talk about now as there was before." With that, she leaped off the balcony and soared into the night sky.
Celestia watched with trepidation as her little sister flew away. She knew that Luna was having trouble adjusting to her former role, and tried to dismiss the bitterness in Luna's voice as a passing mood, but another voice deep down in Celestia's gut told her that she had read this story before - in fact, she'd written it - and she knew exactly how it ended. Last time, bitterness became anger, Luna became Nightmare Moon, and Celestia ended up as the sole ruler of Equestria. Could it really happen again?
Celestia shook her head mournfully, knowing full well that her duty as the leader of Equestria meant that she had to take this threat seriously. She hurried to her personal chambers, where she summoned a quill, an inkwell, and a small scroll of parchment to her side. Dear Twilight Sparkle, Celestia began to write, I apologize for writing you at this late hour, but I fear Equestria may once again need the services of the Elements of Harmony—
High above Equestria, Luna attempted to come to grips with her emotions as she flew over the cold, whitewashed walls that marked the Canterlot city limits. She thought she had gotten past all this, she told herself. Ponies worked and played during the day, and slept during the night. They did not mean to slight Luna with their behavior; rather, it was just the way things were. Besides, there were plenty of creatures who enjoyed her beautiful night. There were bats, and raccoons, and owls, and even hedgehogs who were active right now! She assured herself that even a few ponies raised glasses in her honor, like the third-shifters and all-night revelers who operated under the moon's watchful gaze. She had never met any ponies like this, sadly, but she was certain that they existed.
Still, as Luna looked down at the empty fields, open roads, and quiet forests beneath her, she could not help but feel an emptiness in her heart. Why do they all take us for granted? she asked herself. Surely they know that nights like this do not simply happen. We have always taken great pride in our work, and yet the better our performance, the more we are ignored.
Luna looked up at the sky above her, marveling at the stars that shone in the distance. Just look at them all, she thought. 'Tis a sparkling masterpiece, with nary a cloud to spoil the view. Was this scene any less beautiful than that of a bright spring day? And yet without anypony to enjoy it, it is as worthless as a painting without a gallery to hang in. Luna sighed at the thought. Perhaps the world feels we are worthless as well.
An image of Nightmare Moon began to materialize in her mind, but she quickly dismissed it. Shrouding the land in eternal night would accomplish nothing, and she had too much love and respect for her sister to ever travel that road again. Still, she thought to herself, couldn't we find even one pony in the world who appreciated all this? Was that too much to ask?
Looking back down, she found herself arriving at her first destination: Ponyville General Hospital, a large, generically-sterile facility on the road between Canterlot and Ponyville. She always hated coming here; regardless of how bad her mood was when she arrived, witnessing the pain and suffering of the ponies inside always made it worse. Still, she also knew that these were the ponies who needed her the most, ponies to whom a quelled nightmare and a comforting word would mean the most. Factor in the possibility that not every pony would make it to the next morning, and the hospital became a no-doubt first stop on Luna's rounds.
Landing on the roof of the clinic, Luna made her way to the foal's ward on the fifth floor, knowing full well that this was where both her heartbreak and her impact would be amplified the most. She began by approaching the main nurses' station on the floor, to get a head count of the patients inside. "How many?" she asked a white-maned nurse who was standing at the station.
"Only fourteen," the nurse replied. "I guess we're lucky tonight."
"Good." Luna paused to give an acknowledging nod to a group of doctors that walked by. "Whom should we visit first?"
"Well—" The nurse pointed her hoof at a doorway due east of the station that seemed slightly brighter than the rest. "I'd say her, if we could get her to go to bed. She came to us from a clinic in Baltimare this morning. Apparently it's cancer, and it's moving fast. They didn't know if she had six months or six hours."
A lump began to form in Luna's throat, but she swallowed it down and nodded. "We will save her for the end," she decided, "to give her some more time to fall asleep."
The nurse nodded, and directed Luna to another door on the other side of the ward.
Mercifully for Luna, most of the foals in the hospital that night were dreaming pleasant dreams. She only needed to intervene in two dreams, saving a colt from a pack of timberwolves and convincing a filly with a broken leg that she would, in fact, be able to play the piano again after she healed. She completed her rounds in the ward in less than ten minutes, predictably finding that the sick filly she had saved for the end was still awake. Luna decided to give the child a bit more time and moved on to some of the more critical adult wards in the hospital.
When Luna went to check on her three floors and thirty minutes later, however, the child's light was still on. At this point, given the foal's condition, Luna decided that she could wait no longer, and that she would have to intervene while the child was still awake. She did not like to do this, given that rules that could be bent or broken in a dream tended to be more binding in reality, but she was still confident that she could do whatever was necessary to soothe the young filly's soul.
"We are going in," Luna told the nurse she had spoken with earlier. "What is the child's name?"
"It's Cassiopeia," the nurse answered.
"Cassiopeia?" Luna was a bit surprised to hear the archaic moniker. Cassiopeia had been a popular name in eastern Equestria in the years before Luna's banishment, but it had fallen out of favor long before her return.
"It's an old family name," the nurse explained. "We call her 'Cassie' for short."
"Very well." Armed with a name and her confidence, Luna stepped into the dimly-lit hospital room. The room itself was painted a sterile white color, and had all the comforts that one would expect, including an adjustable bed, several uncomfortable-looking chairs, and a small table with a vase of flowers sitting on it and several balloons tied to one of the legs. What surprised Luna, however, was the sight of a Mare Instruments StarLite Five Thousand telescope standing on a tripod next to the bed, pointing towards a nearby window. The scope was one of the most expensive and sophisticated on the market, and was considered a must-have item for serious star watchers. Luna couldn't help but chuckle as she imagined her sister's know-it-all prize pupil, Twilight Sparkle, drooling over the fancy telescope.
Lying in the hospital bed, engrossed in an obscenely-thick tome about astronomy, was a small earth pony filly who was made to look even tinier by the large bed she rested in. Her coat appeared slightly off-white in color when contrasted with her bedsheets, its luster sapped by the grueling treatment she had been undergoing, and she wore a dark blue, ill-fitting wig on her head to cover for her mane's absence. While her cutie mark was not initially visible, her choice of reading material gave Luna a pretty good idea of what the filly's special talent was.
"Greetings, Cassie," Luna said as she walked into the room. "It seems awfully late for such a small filly to be awake, especially one your condition. Tell us—er, tell me, why are you not sleeping?"
Cassie looked up from her book. Her blue-green eyes, at first a bit droopy from exhaustion, popped wide open at the sight of her surprise visitor, and it took her a few seconds to find her voice. "P-P-Princess Luna!" she finally managed to say, as she bowed her head deferentially. "W-What are you doing here?"
"It is our—my duty to travel Equestria while the moon is high and watch over the dreams of its subjects," the princess explained. "Is that why do you do not rest, young one? Are you frightened by what you see when you close your eyes?"
"No, it's nothing like that," Cassie replied, "It's just—" The filly pushed her book aside, and scooted across her bed towards the telescope. "I don't have much time."
"You don't have time?" The response sent an arrow through Luna's heart, as the princess realized the filly was all too aware of her prognosis. "Come now, you mustn't speak like this," Luna reassured Cassie. "We know your prognosis is serious, but it is by no means a death sentence."
"Oh, I wasn't talking about that," Cassie revealed, peering into the telescope. "It's just that this is the first clear night I've seen in a long time, and I don't want to waste it."
"We—I see." Luna walked over to the side of the bed and watched as Cassie moved the telescope, scanning the sky through the window. "What are you looking for?" she asked.
"I'm looking for Canis Minor," Cassie said. "It's supposed to be visible this time of year, but I can't find it."
"Canis Minor?" It was one of the more-obscure constellation requests Luna had received, but nothing her inner-star-geek couldn't handle. "It is small, but easy to find if you know where to look. Train your telescope on Gemini, and look south from there."
Cassie followed Luna's instructions. "There it is!" she squealed.
Luna smiled at the filly's success. We have not lost our edge, she thought to herself.
Cassie pulled back from the telescope and scooted back over to her book. "Canis Minor was discovered several hundred years ago by Ptolemy the White-Haired," she read aloud, "and consists of forty-seven stars, the brightest of which—"
Luna could not help but chuckle at the inaccurate number. "Oh my," she declared, "your book is sorely out of date. Believe me, there are many more than 47 stars in Canis Minor."
"Really?" Cassie scurried back over to her telescope to confirm Luna's claim. "I don't even see forty-seven stars in it," she admitted. "How do you know there's so many?"
"Er—" Luna hesitated as she searched for the right words. "You might say that I have had a different perspective on stars than most ponies."
"Oh wow," Cassie whispered, a bit in awe at the princess's knowledge. "D-Do you think you could help me learn about stars and constellations and stuff?" She pointed a hoof at the book sitting on the opposite side of the bed. "That was the only book they had downstairs, and it's really hard to read. I'll bet you know everything in there already!"
"Well—" The offer left the princess conflicted. On one hoof, Luna hadn't had a decent discussion about astronomy with anypony since before her banishment, and it was refreshing to finally find somepony who appreciated her work. On the other hoof, however, her original goal was to make the filly fall asleep, not keep her awake all night looking at the sky, and she still had most of her nightly rounds to complete.
Luna deliberated over the choice for a moment, then decided to split the difference between them. "Very well," she told Cassie. "I shall help you learn about the stars, on one condition: The lesson will last for thirty minutes, and you agree to go right to bed afterwards. You will need your strength for tomorrow."
"It's a deal!" Cassie agreed enthusiastically. "Thank you, Princess!"
Luna walked over to the window, and peered out to see what constellation to target first. "You've already looked up Canis Minor, so let us start from there. Adjust your telescope twenty degrees to the west—"
Luna proceeded to break her own rule and spend the next hour directing Cassie across the sky, schooling the filly on the forms, stars, and histories of the constellations that were visible. She even mentioned some of the mythology surrounding the major constellations, such as how she threw a manticore into the sky to create Leo, and how a handsome suitor had long ago created Virgo in tribute to her beauty. (One of the perks of being 'Princess of the Night' was that she had a monopoly on constellation myths.)
Through it all, Cassie proved a willing and able student, dutifully following Luna's instructions and asking questions about star brightness and whether some stars had other objects orbiting them or not. It was her enthusiasm, however, that caught Luna's attention the most. Most ponies, even ones she considered her peers, tended to have their eyes glaze over when she started talking about luminosity and other facets of stars, but the sick filly before her couldn't seem to get enough of such topics. Perhaps she was too young to have fallen prey to academic cynicism, or maybe she realized the true importance of the topic, and how understanding it could bring great advances to ponykind. Heck, maybe she was just dazzled by shiny objects. Luna didn't know where Cassie's interest stemmed from, and quite frankly, she didn't care. She was just excited to meet somepony who shared her appreciation of the night.
For its part, the sky was up to the challenge of entertaining a curious filly, and was chock-full of interesting stars for the two ponies to explore. Unfortunately, sitting smack-dab in the middle of these stars was the one constellation Luna did not want to see: Cancer. Yes, it was just a crab's pincer, but the name was still a loaded term, and Luna judiciously decided to ignore the constellation for this lesson.
"We—I am afraid that we must end our session," Luna informed her student, upon realizing that she had run out of both time and non-Cancer constellations to describe. "It is time for bed."
"Awww," Cassie pouted. "Do I have to?"
"Now, now," Luna reminded the filly. "We had an agreement, remember?"
Cassie sighed, and crawled back over to the center of the bed. "Princess?" she asked. "Can I ask you one more question, before you go?"
"Very well," Luna agreed. "What is on your mind?"
"I've been wondering about something," Cassie explained. "What does the Cancer constellation look like?"
Luna winced at the question, realizing that once again, her young charge was a bit too self-aware for comfort. "I had hoped you wouldn't ask," Luna admitted, pointing back towards the window. "It is up there now, a few degrees northwest of Canus Minor."
"Okay." Cassie quickly slid back over to the telescope and began hunting for the constellation.
"The stars are rather dim," Luna continued, "but you should see a triangle of stars, with a few sitting above one of the tips in a roughly-straight line."
"I see it," Cassie announced, though it was in a more business-like tone then she had been using before.
The two ponies sat in silence for about twenty seconds, as Cassie scrutinized the constellation through her telescope. "I don't get it," the filly finally declared, pulling back from the telescope and looking over at the princess. "I thought it would be more... scary."
"The name refers to the claw of a crab," Luna explained. "The medical definition of the name came much later."
"It's just—" Cassie stopped, and looked down at the floor by the bed. "Whenever the doctors talk about it, they sound so... serious. Whenever they mention it to my parents, Mom gets really upset."
"It is a very serious topic," Luna admitted, "and one that makes many ponies emotional."
"I even saw my dad crying yesterday," Cassie continued, "and he's the biggest, strongest, most toughest pony ever!" Cassie shook her head, and looked back up from the floor. "I thought anything that could make him do that had to be really scary."
While Cassie's voice remained strong and betrayed little emotion, Luna could see the fear in Cassie's eyes as the filly spoke. "And does cancer scare you as well?" the princess asked.
"Not that cancer," Cassie replied, gesturing towards the window, "but mine... well... maybe a little."
Luna took a deep breath. "Cancer is indeed a powerful and dangerous thing," she told the filly, "but it is not invincible. You are in the hooves of a dedicated team of professionals—ponies who I have seen perform incredible feats and bring many ponies back to health. I know you are concerned, and rightfully so, but know that you are in the right place, and that the ponies here will do whatever it takes to make you feel better."
"Okay," Cassie agreed.
"However," Luna went on, "to overcome this challenge, you must match the dedication of your caregivers. Do not let this foul disease defeat you on any front. Keep your spirits high, and attack each day with a sense of purpose. Draw strength from the ponies around you—friends, family, fellow patients—and lean on them in times of weakness. Above all, keep your sights on your goal of victory, and direct all of your energy towards achieving it. Understand?"
"Yes," Cassie acknowledged. "T-Thank you, Princess."
The princess glanced over at a clock on the wall. "We—I have seen your passion for astronomy, and I believe that if you bring the same passion to your treatment, you will triumph over this disease. Right now, you should get a good night's rest in preparation for tomorrow."
"All right." Cassie's tone contained a hint of disappointment. "It's just—I wish I had more time to look at the stars. You can't see anything during the day, and by the time it gets dark, I have to go to bed."
"Do not concern yourself with this," Luna advised. "You shall get your chance in time, but for now, you must focus on the matter at hoof. The stars will always be waiting for you."
"I know," Cassie conceded, "but sometimes I wish the sun would just stay hidden, so I could study the stars even during the day, without worrying about my bedtime." The filly shook her head, and rolled back to the center of her bed. "Sometimes," she admitted, "I wish the night would last—"
"Forever," Luna interrupted, finishing Cassie's sentence. "In truth, we—I once felt the same way, many moons ago, but I have since learned that this is an impossible dream. Without the sun, the plants would wither away and die, and we would perish along with them. As beautiful as the night may be, it must always give way to daylight."
Cassie sighed and laid her head down on her pillow. "Maybe I'll get to see the stars again tomorrow night," she whispered.
Luna watched as Cassie's eyes slowly began to close, unable to keep herself from smiling at the preciousness of the scene. "Good night, child."
Suddenly, Cassie's eyes popped back open wide. "Um, Princess?" she asked, a little embarrassed. "Could I use the bathroom before I go to bed?"
Luna could only shrug, knowing that she was up against a force that was even more powerful than herself. "Of course."
Cassie quickly hopped out of bed and scampered to the small bathroom in the corner. As she did so, Luna took note of the cutie mark on the filly's flank: a set of five stars arranged roughly into two lines, with a thin blue line zigzagging between them to from a W-shape. While the stars were certainly not a surprise, Luna thought it odd that their arrangement did not correspond to any constellation that she could think of.
As Cassie shut the bathroom door, Luna decided that it was time to take her leave, and quickly turned and left the room. She made her way back to the roof of the hospital, and leaped into the sky to continue her nightly rounds, knowing she would have to pick up the pace to make up for her time with Cassie. While her head admonished her for spending so much time dealing with a single pony, something deep within her heart told her that it had been time well wasted.
The remainder of Luna's rounds passed by uneventfully, and even if they had been exciting, it was doubtful that Luna would have even noticed. Throughout the night her mind kept returning to her chance encounter at the hospital and the time she had spent showing a young filly around the night sky. The princess had enjoyed giving the lesson as much as Cassie had enjoyed listening to it, perhaps even more so. While she had participated in many fruitful discussions about astronomy before, they had all been purely academic exercises, with no thought to the aesthetic value of the subject matter. Sure, Betelgeuse was over six hundred light years away, and was of the oldest stars known to ponykind, but what about the way it shined at night? Wasn't it beautiful? Until now, nopony had ever cared about that.
Cassie cared, though. Despite her youth, she saw the night the same way Luna did. She appreciated the artistry behind it, so much so that she wished she could see it during the day. Of course, as Luna had learned the hard way, such a request was impossible.
Or was it? The wheels began to turn inside Luna's mind, unleashing radical thoughts that she could not suppress. Perhaps everlasting night was infeasible, a voice inside the princess's mind said, but what about something shorter? What if the night lasted for, say, a day, or a few days? What would be the harm in that?
"No!" Luna suddenly shrieked, reaching up and slapping herself hard across the face. "We mustn't think like that!" she chided herself. "We cannot risk backsliding into darkness! We cannot risk re-awakening the nightmare!"
But think of the child, the voice continued. She wishes to admire your work, but she is stuck trying to squeeze in a few moments of observation before going to bed. A brief extension of the night would allow her more time to do something she enjoys, without upsetting her sleep schedule and weakening her constitution. It would help to keep her spirits high, and inspire her to keep fighting. Maybe a little more night is just the thing she needs to prevail over her condition. Isn't that worth the risk?
"But what if we cannot finish what we start?" Luna countered. "What if we cannot control ourselves? What if helping her rise leads to our fall?"
If you are truly that weak, the voice declared, then the nightmare's return is inevitable, regardless of what becomes of the foal. Wouldn't you prefer your road to hell be paved with good intentions?
"W-We just don't know," Luna admitted.
You asked the filly to be strong, the voice pointed out. You must ask the same of yourself.
Luna sighed. "You are right," she agreed. "If we wish to help Cassie, then we must be strong—and we will be."
There is no 'we' here, the voice reminded Luna. There is only you, and that is enough. You are strong.
"I am strong," Luna proclaimed, "and if Cassie can face her demons, so can I."
A new-found energy surged through Luna, and she began flying through the air at double her usual pace. She knew what she had to do and knew she was strong enough to handle the consequences. She was less sure, however, if she would be able to convince her sister of these facts.
Princess Celestia waited on the balcony outside the castle kitchen when Luna finally returned to Canterlot. "You are late," she remarked, pointing towards the faint light that was beginning to emerge from behind the horizon. "Did something happen during your rounds?"
"Yes," Luna confirmed. "There is an urgent matter I must speak with you about."
"Oh?" Celestia was caught a bit off-guard by Luna's sudden desire to talk, given her hostile tone from earlier in the evening, but she was more than happy to accommodate the request. "Of course. What is the matter?"
"I do not think you will like this, but please, hear me out," Luna cautioned. "I was wondering if it would be possible to leave the moon in the sky, and let the night last a bit longer."
Princess Celestia eyed her sister with a mixture of sadness and resignation. It was the topic she was afraid Luna would broach, but it was a confrontation she sensed was coming, and she was prepared for it. Celestia cast a quick glance behind her at the window adjacent to the balcony, where Twilight Sparkle and her five fellow bearers of the Elements of Harmony waited inside. Celestia had summoned the six ponies out of fear that she was on the verge of losing Luna to the darkness again, and she could not risk putting Equestria in peril.
Celestia thought for a moment about calling Twilight and her friends outside, but something stopped her. Something told her that things were different this time. After all, the last time this topic had come up, Luna had told Celestia in no uncertain terms that the moon was staying up, and that Celestia could stick her sun where the sun didn't shine. At least Luna was asking her about the idea now. Did that mean there was still a chance of reaching Luna before it was too late?
Before Celestia could respond, Luna spoke up again. "I sense that my request troubles you," Luna observed. "In truth, it troubles me as well, for I do not know what it will lead to. But please, allow me to explain."
Luna began telling Celestia about her entire encounter in the hospital with Cassie. She talked about the filly's fascination with stars, and how much both she and Cassie enjoyed bonding over their love of the night sky. She explained Cassie's grim diagnosis, and how she had tried to reassure Cassie that she was capable of overcoming her plight. Finally, Luna worked through the logic behind her strange request, and how much she felt it would help her young friend, regardless of what feelings it might awaken inside herself.
Celestia listened to Luna's story without expression, and remained expressionless for several minutes afterward as she mulled over the idea. Finally, she turned away from Luna, and began walking back towards the window. "Sister?" Luna asked. "Where are you going?"
Celestia stopped, looked back, and gave her sister a small smile. "I must go apologize to my student for summoning her at such a late hour," she replied, "and begin writing my speech to explain to Equestria why the sun will be taking the day off."
Luna smiled back at her sister. "Thank you."
As Celestia went back inside, Luna turned and gazed out upon the city of Canterlot, which was its usual radiant self under the moonlight. This shall be perfect, Luna thought to herself. Cassie will not have to squeeze in her observations before bed, for she will have all day to admire the stars—
Suddenly, a thought struck Luna, and she looked back up at the stars. "She has already seen these constellations," she said to herself. "They may not seem as interesting the second time around. This will not do at all." Normally, shifting around the stars was a weekly chore for Luna, and was done in accordance with a strict chart she and her sister her drawn up many years ago. Tonight, the princess decided, would be an exception.
Firing up her magic, Luna began scattering constellations all over the sky, hiding the ones normally visible at this time of year behind the horizon, and putting other constellations in their place, packing them together as tightly as she could. (She took exceptional pleasure in shoving Cancer out of sight.) The entire exercise took about ten minutes, culminating in a spectacular view in which constellation stars outnumbered the other, unaffiliated ones. Luna knew it would be a mess to clean up later, but if it had its intended effect, it would be worth it.
As she moved the final set of stars into place, Luna stepped back and scrutinized her work. The scrunched nature of the constellations didn't bother her—in her mind, one could never have too many stars in the sky—but it lacked that extra touch, that special something that would make it more memorable. Thinking back to her final moments with Cassie, inspiration suddenly struck the princess, and she dragged a few last stars back from behind the mountains to occupy a special place in her masterpiece.
After Nightmare Moon's return, the threat of eternal night had been eclipsed by greater dangers, ones that involved chocolate rain and body doubles, and thus the general reaction to Luna's "day of night" was much less paranoid than the princesses expected. Some of the earth ponies grumbled about the loss of, as Element-of-Honesty-bearer Applejack put it, "a perfectly good plantin' day," but by and large, ponies went about their daily activities as if nothing was different.
In an attempt to allay the fears of her citizens and make Luna feel a bit more accepted by the public, Celestia sold the event as "a day of lunar celebration" in her speech, and even put together a small ceremony in Canterlot that fêted Luna as 'the protector of our dreams.' The ceremony wasn't very well attended, but Luna smiled and waved her way through the event nonetheless, knowing that the sun-less day was not really meant for her anyway.
Back at the hospital, Cassie greeted the news of the sun's day-long vacation with a high-pitched squeal of glee, followed by a demand that somepony find her a decent book on astronomy. She spent the entire day glued to her telescope, only abandoning her post for a few hours for her scheduled cancer treatment, and even then it took three doctors to drag her away from the window. By early afternoon, she had scrutinized, identified, and cataloged every star, comet, and galaxy she could lay her eyes on, and even attempted a few sketches to try to capture the true brilliance of the scene.
One particular set of stars, however, drew special interest from the filly. It was a group of five stars sitting close to the moon, arranged roughly into two lines. It seemed too orderly to not be part of a constellation, but none of her textbooks mentioned anything about them. At a loss for what else to do, Cassie decided to appeal to a higher authority for assistance. "Mom?" she called over to a light-blue pony standing by her bedside. "Do you know what those stars are?"
Cassie's mother walked over to the window, and followed Cassie's pointing hoof to the mysterious stars by the moon. She recognized the pattern immediately. "Why, Cassie," she observed, "those stars look just like your cutie mark!"
"They do?" Cassie lifted her blanket and peered at her flank for a moment, then went back to the telescope. "It is!" she agreed. "It is my cutie mark!"
In that moment, it struck Cassie: This wasn't a random arrangement of stars that some long-ago astronomer had interpreted and assigned some cryptic meaning. This was a gift from her new friend, a stellar work of art made just for her "Thank you, Princess," Cassie whispered, "for everything."
The events of the days and weeks that followed remain a source of debate to this very day. Some ponies say that Luna's actions did indeed inspire Cassie to keep the faith and never give up the fight, while others claim it was a triumph of modern medicine more than any faith-healing exercise. A few conspiracy theorists even claim that Princess Celestia interceded in the name of national security, afraid that Cassie's death might send Luna into an even deeper state of despair, and create an opening for Nightmare Moon to rise again.
What we know for sure, however, is this: Soon after her meeting with Luna, Cassie rebounded from her grim prognosis. Her cancer went into remission, and eventually disappeared altogether. She grew from a curious filly into a smart, inquisitive young mare, knowledgeable on many subjects, most of all the workings of the night sky. Most importantly, she maintained her friendship with the princess of the night, and eventually became a student of Luna's, serving under her as Twilight Sparkle had once done for Celestia.
Cassie never became a princess, but in truth, she found her own way to live on forever. Even today, if you're lucky enough to find yourself spending an autumn in the Northern Hemisphere, you can still see those five stars arranged in a zigzag pattern in the sky, an everlasting reminder of a friendship forged over a shared appreciation of the beauty of the night.