The heavy slab of oak separating the classroom from the narrow hallway shut with an audible resonance. Luna slowly walked across the bare wooden floor. Lunch had been rapturous, as always, and imposed upon her a sort of benign malaise that was to be expected after such an excellent meal. Approaching the tall windows in the back of the room in a trance-like state, she haphazardly crawled into the plush lounge chair waiting in the corner for such occasions.
Whenever she wasn’t teaching or eating, she was usually sleeping. And her next class wouldn’t be for two hours.
Suddenly, and without warning, the room was filled with a deafening cacophony, like a small hurricane had somehow found its way into central Scotland. Luna’s eyes flashed open, just in time to see a massive white object strike her directly in the face with the momentum of a freight train, knocking over the chair and sending her and the supersonic mass onto the floor.
She lay there for a while, paralyzed by the physical shock. She probably would have gotten a concussion, if she were mortal. She thought that it might have been another bludger gone astray from the Quidditch pitch, or even a ghost that had assumed corporeal form. Her sister was the last thing on her mind when she heard the solar princess herself moaning just inches from her face.
“Ugh….” she said, lifting herself from the gnarled mass of pony on the floor, “I think I need more practice with the transport spell.”
“Celestia!?” Luna exclaimed, “What are you doing here!?” The sight of her sister in the antediluvian chambers of Hogwarts was incongruous.
“What am I doing here, sister?” Celestia retaliated indignantly, “What are you doing here?”
“I… I…”
“You’ve got some gall,” Celestia interrupted, “sneaking off in the dead of night and coming back here.”
“Sister… I…”
“You’re not a filly anymore, Luna” she scolded, magically replacing some papers knocked from the desk by her impact. “You can’t keep doing immature things like this, Luna. I’ve spent all week looking for you!”
“…all… ….week?”
“Of course,” Celestia confirmed, “You disappeared on Sunday, and today is Friday.”
“Celestia, I haven’t been gone for a week, I’ve been gone for months.”
The older sister was dumbstruck by this new information. “Months?” she hesitantly wondered. “How is that possible?”
“I don’t know exactly, but it seems there’s some sort of variation in the passing of time between the two universes,” Luna suggested, “The first time, I was here for almost a year.”
“A year!?” Celestia said, shocked. “It was just a fortnight, in Equestria.”
“Hmmm… perhaps, then, this universe is speeding up,” her sister postulated, “or, the other one is slowing down. I’m not sure. I think we should consult Discord on the exac–”
“Discord!?” the sun princess shouted, “Why in the name of Faust would we consort with such a scoundrel?”
“I’ve seen him. Here.”
“...How!?”
“It’s complicated,” Luna began to explain. “He was a student, here, at Hogwarts.”
“There’s no way—”
“He was a human, then. About fifty years ago—”
“Fifty!?” Celestia protested. “We battled Discord thousands of years ago. Do you not remember, sister?”
“I could not possibly forget, Celestia,” Luna plaintively said, “but like I have said, the time scales between here and Equestria vary vastly. It is entirely possible that they were once so different in speed that a year here could be a century there. We must consider every possibility.”
“How did he find himself in our world? And how did he become so… disfigured?”
Sighing plaintively, Luna began to explain to her sister all that Discord had elucidated to her just a few days before, from the troubled childhood of Richard Fenwick, to the doors hanging inertly in the cosmic stew. Celestia took a seat on the floor, eyes opened wide with bewilderment at every word.
“That is… shocking, to say the least,” Celestia said some time after Luna had finished, “But… are you certain that he is to be trusted?”
“I believe so,” she answered. “I saw it with my own eyes, sister. This is no trickery. Everything that we know is in danger, and Discord could be our only hope.”
“It is not so easy for me to put my faith in our oldest enemy,” Celestia contemplated, “but we must set aside out differences when faced with a greater enemy.”
The two sat there in silent contemplation, until Luna abruptly leaped towards the large alicorn on the floor, enveloping her in a passionate embrace.
“I missed you, sister.”
“I missed you too, Luna.”
“How will they manage without you?” Luna asked. The two had settled down in the classroom, musing over the situation in Equestria and her stay at Hogwarts over tea, which Luna had ordered clandestinely from the kitchen, not wishing to cause a brouhaha over her sister’s sudden apparition.
“Oh, they will be fine,” Celestia said, gently mixing two cubes of sugar into her cup, “Twilight and her friends are there with the Elements in case of emergency.”
“But who shall raise and lower the sun and moon while you are away?”
“Luna, you know as well as I that while those duties are ceremonial cornerstone of our reign, they are not particularly magically strenuous. The directors of the Canterlot School of Magic were willing and able to accept the responsibility.”
Luna leaned back in her grand desk chair, contemplatively taking a sip of tea. “I see that I am not hard to replace these days” she said trenchantly.
“It is necessary, Luna, if you are going to take a sabbatical to another dimension every other weekend,” her sister replied, her tone becoming grim again. “I must admit, that I did not come here merely to see you, sister. Equestria may be in danger, and I need your help.”
“Like you needed my help with Discord, or the changelings, or Sombra?” Luna balked. “I’m sure that the bearers of the Elements can solve this one, like all the others.”
“Luna,” Celestia berated, “Whatever I did, I did to protect you. Now, this is different. This threat is not from our world. I’m afraid that it rather fell in, so to speak, when the portal was last open.”
“Lord Voldemort” Luna stated with a tremble of revulsion.
“Exactly. You have experience fighting him. Experience that I need.”
“If it’s Voldemort that we are to face, there are a few here that know him better than I.”
“Excellent!” Celestia said, delighted, “Do you know where they are? Could we perhaps request their assistance?”
“Come with me, sister,” Luna replied, getting up, pushing the tea service aside, “We’re going to see the Headmaster.”
The door leading to the hallway was blocked by a coalescence of students in nearly-identical grey uniforms. Luna cursed at herself for her own stupidity; she had forgotten her next class. Forty curious eyes fell upon her as she pushed into the assembly.
“Class is canceled,” she announced apathetically, “go do something else. Try not to kill yourselves.”
“Why?” asked one disappointed youth.
“Family emergency.”
“Like the ‘family emergency’ last month when you went to the Sex Pistols concert?” japed one voice from the crowd.
“That was different,” she said, “This is serious.”
“Is there a problem, Luna?” Celestia feebly asked from behind the shut doors, afraid to show herself to the alien youths.
“Who is that?” another student demanded, pointing behind Luna.
“Family.”
“Why are they staring?” Celestia nervously asked her sister as they made their way through the halls, attracting the gaze of several students and staff alike. “Are they not accustomed to your presence?”
“Oh, it’s not me they’re concerned about,” she nonchalantly answered. “It’s you.”
“Me?”
“Half-giants? No problem. Werewolves? No big deal. One trans-dimensional brightly-coloured alicorn princess? Perfectly acceptable,” Luna jested, “But two?”
Her sister’s comment induced a small chuckle in Celestia. As she walked through the old stone castle, she could not help but notice that many of the students, especially the younger ones, shied away from her sister, almost shaking with an impalpable trepidation.
“You’re not exactly revered by your students,” Celestia noted.
“I’m a strong believer in the principles of Niccolò Machiavelli,” Luna said.
“What?”
“Philosopher,” Luna said, remembering her sister’s complete ignorance of Earth culture. “Long story short, to be feared is better than to be admired.”
“You seem to inspire a frightening mix of the two,” Celestia commented. Luna laughed.
“Oh, great,” one pupil audibly remarked as they passed, “There’s more of them.”
“Watch it, Goyle,” Luna answered, “Or you might lose the other one.”
Goyle’s face immediately snapped into a look of infinite horror. If it weren’t for Crabbe standing next to him, he probably would have passed out.
“It’s a long story,” Luna said, answering the question never asked in her sister’s puzzled expression.
After a long and awkward stroll across the campus, the two finally arrived at their destination. As her sister looked on, confused, Luna approached a large state of a gargoyle that seemingly stood in the middle of an empty hallway.
“Cauldron cakes” she whispered to the statue.
“What?” Celestia asked, as primeval, magical machinery moved underneath them. Suddenly, the firm stone beneath them gave way, and they found themselves falling down a narrow vertical corridor. Luna smiled and gently glided downwards into the abyss. Celestia, taken by surprise by the fall, completely forgot the employment of her wings, and inelegantly landed on her back on the rough burgundy carpet.
“Ow.”
Dumbledore looked up from his desk, and was greeted by the sight of the Head of Ravenclaw House, and what appeared to be the still-living corpse of an winged albino moose, moaning in pain.
“I like the new entrance, Albus,” Luna said, then looked to her sister lying on the floor like roadkill, “but perhaps you should have informed me in advance?”
“I concur,” Dumbledore said, standing up to study the majestic creature capsized upon his office floor. “Your sister, I presume?”
“The pleasure is all mine,” Celestia murmured.
“Get up, Celestia,” Luna ordered.
Groaning, the white alicorn lifted herself from the floor, and flashed her wings in an obvious attempt to restore her last scrap of dignity.
“Albus Dumbledore, Headmaster,” he said, hesitantly offering a hand, unsure of if or where it would be shaken.
Celestia graciously placed her gilded hoof in the Headmaster’s hand, forming a rough emulation of a familiar gesture.
“Luna has told me much about you,” Dumbledore said.
“Is that so?” she answered, turning to her sister. Luna smiled guiltily.
“I was not informed that you would be visiting,” he said, “I would have planned a ceremony.”
“Oh, I am not here to visit. There is important business, and I needed Luna’s help.”
“Voldemort’s back,” Luna said, finally revealing the unwieldy and inevitable truth. Dumbledore looked at her, aghast.
“Not here,” Celestia added, trying to prevent the Headmaster from having a heart attack, “In our world.”
“Ah… yes,” Dumbledore said, trying to recover from the initial shock, “interesting.”
“I was hoping that Luna could come back with me,” Celestia requested, “she has more experience fighting him than I.”
“I see,” Dumbledore said, gently stroking his beard with a curious expression. “But that is not the only reason you are here, yes?”
“No, sir…” she answered, like a student being reprimanded. “I missed my sister.”
“I expect that you would.”
“I can’t just leave, Celestia,” Luna interrupted. “I have a job here. I have a life here.”
“Luna,” the elder alicorn pleaded, “You are my sister, and I need you to come home.”
“You can’t just tell me what to do! I don’t want to go back!”
“You cannot stay here, Luna. Equestria needs you.”
“If I may–” Dumbledore said, attempting to mediate, “–propose an alternate solution?”
The two sisters had by then moved to face each other on the carpet, Luna defiantly looking up at Celestia, who was at least two feet taller. When the Headmaster began to speak, they turned to observe the old and wizened professor, both intrigued.
“What is it, Albus?” Luna asked,
“You will both go back to fight Voldemort,” he began to say. Luna snorted, indignant. “And when he is defeated, Luna will return for the rest of the school year.”
The princess of the night smiled widely and smugly up at her sister, who looked discontent. “Headmaster,” she protested, “I do not think you understand me. Luna needs to return permanently. I thank you for the kindness and care you have shown her here, but this is not where she belongs. She has duties to attend to. She is a princess, not a professor.”
“I’m not a child, Celestia,” Luna grumbled.
“Then why do you act like one?”
“Your majesty,” Dumbledore humbly addressed the princess of the Sun, “I fear that you may not be respecting your sister’s independence.”
“Independence!?” Celestia roared, “I have had to rule alone for over a thousand years, due to her hubris! I cannot allow my sister to cavort about as she pleases.”
“My hubris!?” Luna shouted, “You complain about all those years, but you didn’t spend them on the moon!”
“If I may request,” he intervened again, “that I talk privately with Lu– Princess Luna?”
Celestia thought about this for a second. “Fine,” she moaned, storming out of the office.
Dumbledore watched as the white equine angrily marched towards the door, which she magically shut with a force that made several of the moving portraits behind the Headmaster’s desk fall to the floor.
“I can see the resemblance,” he jested, “stubbornness.”
“Please let me stay, Headmaster,” Luna begged, joining her front hooves in a feeble gesture, lower lip pouting.
“There is no possible way that your sister would allow that,” he admitted, “but there may be a way for you to come back.”
“What is it?”
“If another were to go with you to Equestria, to assist in Voldemort’s defeat, and to ensure your return.”
“None of the teachers here particularly like me, certainly not enough to travel to another dimension,” she said, “Who would volunteer?”
“I would.”