The Return
It was his time.
His time to prove his worth to his elders, and his teacher.
"You are to to go to Equestria, and to eliminate the occupant of Canterlot. Do it quickly. Do not do it for enjoyment. Do not show off. Be quick. Be silent. Be deadly." a black unicorn with yellow eyes said, from within a hooded cloak. Another unicorn in a similar cloak spoke.
"This is the best time to eliminate Celestia. If you fail us, you know what will happen," she said, in a somewhat cold tone. The stallion nodded, gulping silently. "But what about Celestia's followers?" said the stallion, his red eyes looking to the elders as he shifted slightly, from the pressure of all of the great elders standing around them."We will take care of them at some other time. Let the chaos fade. We have patience. We have time." said the first. "Now go," said the elderly black unicorn in a rather demanding tone, his voice dripping with cold lust for vengeance. He bowed before the elders who looked upon him with a blank stare, and then proceeded to exit. He exited the dark temple where they were gathered in, within the confines of a dark forest nearby to a village, outside the jurisdiction of Equestria where none could see their occult activities.
The unicorn stallion looked down at himself, his charcoal black fur, his cutie mark of a dagger, dripping with black liquid. He pulled his set of cloaks on, and pulled the strings tight, which acted as a catalyst for the cloaking spell to engage. He overlooked his hometown, the lights of lamps dimly shining in the distance through the humid nightly air. He pulled out an orb-looking device, snapping it to a holder within the cloaks. The stallion began to float up and fly away, consciously controlling where he would go. Like that - he flew off into the night.
He had studied the land and the paths towards Equestria the past few months, his elders instructing him to do exactly as they said, to do exactly what he was told. It was his time. It was when all of the teachings of the past would fall into play, and he would be the assassin to do the dirty deed. He felt great pride in what he was about to do, there was no question about whether this was right or wrong. He knew exactly what he had to do. He flew higher and higher, faster and faster, the clouds rushing by, this was the best flight orb they had, and he was going to put it to use.
He moved where he was going, correcting it when it needed to be. His trained, honed mind knew exactly where he needed to go, and exactly what he needed to do. Over the river Fangis, over the Hollow Fields, and the neighboring towns in a blitz. Some might hear a whoosh sound in the dark, but they would see nothing, not even a bird. And like that, he continued, farther and farther into the night. He stopped to rest now and then. Within hours he could see the border towns of Equestria, shining with lamps. Not all that different from his town at a glance.
He twisted and curved, to avoid flying over those towns. He kept going. Itching to do the deed. Itching to kill. Itching for vengeance. Many had tried to do this and failed, but with the guidance of the elders, and his malevolent intent, he shall succeed or die trying.
More hours passed until he could see Canterlot in the distance, and so he descended onto one of the roads leading into it and trotted silently. Past the guard patrols, careful not to instigate or let them know anything was up. He knew that there was some sort of magical field around the castle as others had spoken about, however when he entered the town, he ducked around a house corner and pulled out a blue potion. It would give him great energy, as he was tired from all that walking and flying, replenishing him. He glugged it down as silently as he could, it was marvelous, though it tasted quite strange, soon enough he felt its energy seeping into all corners of his body, replenishing him.
Then he unsummoned the empty bottle and proceeded to pull out 7 small stones, with a blue dot on them. These were enchanted stones. They would allow him to turn off the field around the castle, the rarest of magical stones. The ones the elders bargained to get for the past several years until they finally got them from an unknown source weeks ago. It took him a while, but he would set the stones up around the castle and activate them - shutting down the magical protection field that was around the castle.
He proceeded to fly up towards the royal balcony, that would allow him to enter the upper floors where the Princesses slept. He began preparing some spells silently as he walked the upper floors, relishing their architectural beauty, but being careful to not get distracted as he proceeded towards the first royal bedroom. It was where Celestia slept. He waited, as he could see guards patrolling through the night, making sure everything was as it seemed.
A minute passed, and the guards were gone. He slowly opened up the large, grand white door to Celestia's room. It opened with a single creak, then he quickly entered, and closed the door as quickly and silently as possible. Then he performed a binding spell, binding the door to the wall and the floor so that it wouldn't open without considerable force. Then he proceeded to look around the room, it was great, wonderful. Then he saw the bed, with a white alicorn sleeping soundlessly in the bed. He cast a deep deep sleep on her, and she seemed to freeze up in the bed slightly, a dreamless sleep.
He pulled out some sort of black mass, pulsating with dark magic, and proceeded to throw it onto her, it seeped into her, corrupting her from the inside out. Her mane went from soft gentle hues to a more fiery, explosive-looking one. Illuminating the room even in her sleep, her body shifted to look far more terrifying, imposing, and demonic.
Then her cutie mark shifted to that of a burning sun, getting bigger, flames seemingly flowing across her flank from it. He performed a draining spell on her, to drain her of all her magical power, except the dark magic that corrupted Celestia. He kept going and going until there was only a microscopic fraction left, like a drop of water in an empty wasteland. The dark stallion looked on with sadistic glee upon Celestia's transformation. Celestia looked far more imposing and evil now and feared that she would awaken, but she wouldn't. Her mane dimmed to nothingness, her body seemed to fade a bit. Then he sighed quietly and then used the magic he drained from her to create a powerful banishing spell, she started to shimmer and then was suddenly gone once the spell was completed. Gone to the Moon. Those looking up at the moon would see a mare's face begin to appear across its surface, the surface of the moon taking upon a blood-stained orange. The plan was to destroy Celestia's innocent nature, to turn her into a Demon, so that if she ever escaped she would be the demon that Luna always saw in her heart.
Up next was Luna. He had to find her and teleported to the other side of the door after listening to the other side so that he would make sure that no one was on the other side. He did so after quadruple-checking and then proceeded towards Luna's room. One down. One to go, he thought, deeply pleased by his actions. Soon enough he found her room, and waited as the guards passed, talking quietly about the next shift, the next hour. One of the guards was making fun of another guard on the team, making fun of his weight in jest towards him, the other guard seemed to scold him quietly as they continued down the hall.
He opened the door, unlike Celestia's door, it didn't creak. He did the same binding spell, however, he quickly moved towards the sleeping dark blue alicorn and began his corruption spell, unlike the other, it wasn't dark magic, just pure corruption with a taint of personality changing, a liquefied substance that would change her to be extremely logical, merciless, cold, yet just like Nightmare Moon. Luna's body shifted, to look like that of the previously known Nightmare Moon, but as he kept going, she looked more imposing. Her cutie mark shifted to that of a brilliant full blood-stained orange moon, commanding respect, and her mane and tail changed to be bigger, with many stars. It was done. The deed was done.
The grand return of Nightmare Moon has now happened. He let her sleep and exited. Soon enough, all of their kind would be free to return. Nightmare Moon returned in full force - supported by the dark cultists that brought her back. Celestia's banishment into the Moon was a clear symbol of her superiority - while Nightmare Moon enjoyed the pale white moon of before - the blood-stained orange moon was far more appealing to her. Every time she looked at it, she saw justice in her victory.
To return home. Months later, Nightmare Moon had inserted her influence into Equestria again, this time in full swing. Nightmare Moon had begun ruling Equestria with an iron hoof, having those who opposed her reign quietly done away with, in events called 'The Night Terror'. However it wasn't all bad for those who complied, she improved many things of Equestria, if only to increase support for her reign and swoon those to her side. Not all would, though. Across the land, many groups that had supported her had returned from exile.
Nightmare Moon was forever and always a pawn - for these Cultists that struck before, and now they've struck again. Now they've won and inserted themselves into the world at large. The stallion who performed this task ended up being lauded by the Cult, eventually taking upon the task to destroy any references to Celestia and her sun throughout Equestria - starting with those who have cutie marks with the Sun on them.
Every reference to Celestia must be purged.
Every text idolizing her to be burned.
Everyone is to be converted or buried.
The Nightmare has won. Forever.