Lunar Lunacy
Prologue
It had been useless to even try, it seemed: for every spell in her knowledge she performed, it would backfire terribly on the imprisoned mare. Escape seemed impossible, and so the next obvious solution was possession or causing destruction down on Equestria: no such luck with that either. She could no more adjust ocean levels or change weather patterns than she could summon a demon to control a butterfly. All of this newfound power, and yet she could not do a damn thing with it!
“Curse you, Celestia!” Nightmare Moon shouted, snorting and stomping against the dusty soil beneath her hooves in frustration. She had been this close, this close to achieving her dream of eternal night, of finally getting the ponies of the world to love and fear her, and her dear sister had gone and ruined it all! Bucking and snorting and engaging in all the expected panoply of anger, she ran around, kicking over stones and blasting craters into the lunar surface with her newfound dark powers. After several minutes of this, and leaving one very small portion of the moon’s surface resembling a warzone, she slumped onto her backside, the effects of the battle with her sister, her recent outburst and her imprisoning teleportation getting the better of her.
She yearned to shout something terribly cliché, like “We shall have our revenge!”, but she did not. After all, even though the magic of her imprisonment on the moon meant she could breathe and make noise and whatnot, who would listen to her out here? She was doomed to an eternity of exile up here, brought forth by her plans to bring an everlasting night. It had been the perfect plan!
“But noooo, Celestia had to just... go and ruin it!” the queen of the night snorted, stomping her two front hooves deeper into the dusty substrate. “It is insulting to us that, even with all of our newfound power, we cannot yet escape from this stupid place!”
Indeed, the moon is a rather dull place to be for an extended period of time. Sort of like a furniture store, or perhaps one of those grand meetings with the minor nobles that Celestia seemed so impatient with. Either way, it took about three weeks for Nightmare Moon to become bored.
Really bored: the kind of bored where you’d wish anything would happen. Even a meteorite impact off in the distance would be nice, but no, the cosmos was silent in that regard.
So it was that, with her power, Nightmare Moon tried all sorts of things to do: make copies of herself out of shadows and moon dust to talk with, make a giant dust castle for her to live in, and even invent a new form of the alphabet. But, the copies faded away faster than she could begin enjoy them, the alphabet thing was just too dumb to try and continue on her own, and the castle’s halls felt so cold and lonely. To think, she was evil, and yet she didn't like being alone.
So, Nightmare Moon set about trying to open up a portal to another dimension. She had already tried it with Equestria, and if that could not work, then maybe she could at least find a way to a different place, one where she could potentially become a conqueror.
After seven weeks of trying, she managed to open up a portal for about ten seconds. The only thing was, upon trying to go through, she was electrocuted and sent five feet into the lunar dust dunes she had made the week before. For all of her concentration and subsequent attempts, Nightmare Moon soon realized she truly was stuck on the moon; she could not go through any portal she created, no matter how hard she tried nor how long she focused.
After several days of depression at this new obstacle (which was followed by an immediate and somewhat-satisfying destruction and reconstruction of her dust castle), Nightmare Moon thought of a new idea. “If we cannot go through a portal to another dimension... then we shall simply bring something from another dimension to us!”
It was the perfect plan, but sadly, try as she might, almost none of the other dimensions seemed to want to properly “line up” for her magic. They just didn’t exist on a similar or parallel plane, it seemed, and as such, through one such portal, she brought back a tiny creature that looked like a cross between a seagull, a lizard and a mildly obese manatee.
It exploded after phasing in and out of existence for several seconds. It had taken several hours of magical scrubbing to get the creature's ink out of her mane.
After trying with numerous other portals and achieving similar results with quite a few other odd-looking creatures, she settled on one portal in particular that most closely matched her own. She wanted to call it another dimension of her own, but she didn’t know if that was true, or if she simply lived in a dimensional form of that dimension’s parallel dimension.
Dimenception.
At first she tried to bring through an animal that could keep her company, a large flightless pigeon from some uninhabited islands. It froze to death nearly instantly.
“I’ll have to make this place warmer,” the mare said, and thus it was so. The temperature was comparably nice to what it had been, a rather steady seventy two degrees by day and around sixty degrees at night.
Then she tried summoning an army of what appeared to be sapient creatures to her, resplendent in armor and trained in ways she found most appealing. The entire legion suffocated within minutes.
“Guess their empire will never know what happened to them,” Nightmare Moon muttered as she magically swept the bones away and piled shields, armor and swords into the castle basement. “I must give this place air then.”
So she continued this pattern of bringing something through a portal over the course of many, many years, albeit usually less significant than that legion, and the same thing kept happening.
She brings over a flamingo: it flies off into space. Hence, a rule on no flying things and an artificial ceiling made from magic, just in case.
She transports an entire colony of those same sapient creatures as before: they die of starvation within weeks after killing one another for food and shouting something about “Croatoan”. In response (after cleaning up the mess), she comes up with a spell that eliminates the need for food or water, and thus starvation.
She brings through several cow elephants, and for a while, they seemed just fine. They were intelligent, and while they lacked the ability to speak, the mare in the moon found them a comforting presence. Sadly though, after several decades, they all died out, leaving her alone once more.
“An ageless spell,” the queen of the night said as she attempted to open a portal once more. “Whatever comes through now shall have no need to eat or drink, cannot fly, and shall have no fear of the ravages of time.”
And thus, on the one hundred and sixty sixth year of her imprisonment, Nightmare Moon opened a dimensional portal and brought forth a new companion to ease her continued loneliness and boredom.
His first reaction as to his new surroundings?
“What the hell?”