Two worms spin through the darkness, and are met with a blast from the Arc-En-Ceil. They scatter their shards, shedding anything that they have no need of, and begin to fight back.
One remains in the sky, to fight the spaceship that dares fire upon it. The warrior trades fire with the ship, both slipping between dimensions like serpents slip through the grass. Eventually, it is chased directly into the maw of the entire fleet, one created to face threats such as Lost Logia, and ever so slowly, at great cost, it is worn down and finally slain.
The Warrior's mate, the Thinker, descends to earth, shedding more shards as it does. It tries to hide, but encounters a strange beast. A creature born of hatred and malice, a thing that it cannot comprehend.
Strange, illegible runes flash through it's mind, and the being before it, Griselda, Witch of Despair, something whispers, declares it's barrier. Swarms of pathetic beasts attack, and the Thinker, though weaker in a direct fight than it's mate, strikes back, wiping them out with contemptuous ease. It shatters the barrier, firing a Sting to tear apart the dimensions, then fires another to destroy the beast, which retreats into an ornate jewel. The Thinker queries it's shard, the Path to Victory, but is interrupted.
A girl has made a wish. She scoops up the fallen Grief Seed, then rushes forth, hidden from the Thinker's foresight by her Wish. She has sold her very soul for it, for at last, she has one. It grants her the ability to strike this blow, one which separates out from its greatest shards. The silver Worm retreats, acknowledging it's loss. It is met by another human. An old man to the young girl, he too meets his opponent with a blast of raw power. He fought the very moon once, but he has been reduced, and the Worm is beyond him as he is. Nevertheless, it fights across dimensions, and those, at least, he has mastered. He calls upon an infinite number of parallel worlds, locks the Worm from each, and chases the creature down to where the Beast of Gaia awaits. Alaya's Counter Guardians back off, and the Beast is loosed upon the Worm, this invader who has not been invited, who threatens Her.
The two worms have fallen. But they did not leave this world unmarked. But then again, none of the other aliens have either.
The years pass. The hidden is revealed. The Veil is torn away. And civilization as we know it has come to an end. The Worms did not fade easily. With their last breaths, or what passes for them, they wreaked the earth with destruction.
It is a world of superheroes and supervillains, of dead apostles and magi, of magical girls and witches, of incubators and mages.
It is a world where anyone may have power, but where power is held in the hands of the few.
Some are awakened to power by great trauma. They are shattered, and in the shattering, a shard of a Worm offers a pact. It grants them the right to call upon it's power, and in return, it learns. Sometimes it makes a mistake, but quite often, it does help in it's own way. The hosts must struggle with the violent tendencies of their Shards, but in the end, they are the most normal.
Others make the deal more directly. They are granted a single wish in accordance with their karmic potential, and with it comes strength and magic, the ability to bend the world to their will. And in return, they give up their very soul. They are doomed to become a Witch, a being born of their grief and despair. But in that fall, they create energy for the incubators to harvest, that they may hold back Entropy for just a moment more. They can hold off that fall though, by hunting their kindred who have already fallen, and taking their Grief Seeds to cleanse their Soul Gems.
The Mages dislike the incubators. Dimensional travelers, and only a few of them native to this world, they wield magic of their own. Magic born from a core within their body, they do not believe that beating back entropy is worth the loss of so many lives. The Incubators call them ungrateful, they call the incubators monsters. Though as a whole they are relatively unharmed by the apocalypse that has come, they have decided to render aid, and they must forge a society themselves.
Magi simply find themselves irritated with so many aliens. They are the only ones native to Gaia's realm, and they are the only ones truly bound by it's rules. In general, they find themselves the weakest, forced to find every last bit of knowledge in their search for Akasha, to bring forth the miracles that the these aliens call upon with little fanfare. Their quest isn't made any easier by the ruins in which the world has found itself, though Gaia seems to have eased up a bit.
This is the world in which you reside. A world of magic and supers, where reality and fantasy become one, where science meets those who would circumvent the laws of the world. A world where 20 Endbringers stalk the earth, only to be fought by the forces that once slew their progenitors. A world in chaos, scraping at the last bits of order, forging a light that will shine through the despair.
Who are you?
[] You are Shirou Emiya. You want to be a superhero who saves everybody. You know that's not the typical path for a Magus, but that's okay, because you were Saved, and so your purpose is to Save others in return. You stand against the villains of the world, but you will Save them as well. In the meantime though, you have to deal with the ruins of Fyuuki. Your lack of magical ability and training is a problem, but these symbols on your hand promise the chance to summon a Servant, if only you can find enough Prana, a Catalyst, and a sufficent payment with which you can apologize for misleading them with a false promise of a Grail.
[] You are Taylor Hebert. You were born in the ruins of Brockton Bay, a city that once was famous for its shipping. Of course, when the Worms arrived, all of that changed. It left your city a burned out ruin. However, one of these shards linked onto you, and when a great source of trauma arrived, it announced it's presence. Your Shard is Queen Administrator, and it has granted you control. This would likely be a good thing if it weren't for the fact that the city is ruled by fractured gangs of murderers, thugs, and nazis, all of whom hate each other, and demand tribute from any survivors who aren't willing to bow down. They also seem irritatingly willing to force other ability users to serve them or die.
[] You are Nanoha Takamachi. You were just an average girl. Well, and a math prodigy, but other than that, perfectly average! You're in the ruins of Uminari, which, uh, isn't actually that ruined anymore. Most of the damage was repaired by the 21 Jewel Seeds that Yuuno lost track of and came to retrieve. The Seeds were wished upon for salvation, and granted it... for a price. Though the city shows little damage at the moment, the Jewel Seeds often cause immense chaos when they go berserk, and their "protection" has also hidden the entire city from the TSAB, who would otherwise assist. You have raw power up the wazoo, and few things are likely to present a threat... to you. To your sadly unempowered family, however? And there's the problem that you've seen traces that another girl, one with blonde hair and pretty eyes, might have come to steal the Jewel Seeds. While that wouldn't be a bad thing, you do need to seal the slowly, properly, and with a lot of carefulness to keep your city from falling apart, and she doesn't seem inclined to do it that way.
[] You are Madoka Kaname. You were just an average girl in a small group of scavengers in the ruins of Mikihara. No really, you were perfectly average, not notable at all. But then a black hair girl showed up, her eyes frantic, claiming that everything was wrong, and she was going to save you, damnit! Though you have no power of your own, your fate is heavy, and the karmic potential of a hundred lives you never lived have been tied to you. A single pact could grant any wish, but in return, it would likely destroy the world right after as your Witch came into being. You have your friends though, Kyouko, Sayaka, and Homura are all magical girls, each with their own talents upon which you can call. They'll need Grief Seeds, but they seem willing to follow your lead.
[] Write-In: You are an OC. Pick a power source.
--[] Magecraft
--[] Shard
--[] Linker Core
--[] A Wish
AN:
Why am I doing this? I really shouldn't be. Oh well.
All backgrounds will have to deal with people of all kinds, they just more easily encounter their own kind.
All canons have been deeply affected by the effects of this being a cross-over world. I'll explain more depending on what you know in character.
This is not a CKII type quest... unless you guys want it to be. You want to rebuild the society as a leader? By my guest. You'd rather just explore this horrible world on your own? Go for it.
The TSAB is technically rendering aid. No one trusts them. That's fair, they don't exactly trust the local mages or the Parahumans.
I will likely butcher a bit of characterization at first, but I should be able to settle back into the "flow" of a character after re-watching/reading their source material. In the meantime, apologies, and call me out on it please. If you'd rather avoid risking it, go with a write in.
All characters are the age they are in Canon, but have somewhat different backstories to account for the different setting. The broad strokes are the same though. (Shirou was Saved, the magical girls had "mundane" lives, Taylor has social issues that made her a loner, etc.)
Magical Girls are pitied for their fate but pretty powerful and get that one wish, Mages are quite powerful but insanely rare on earth and don't work very well without infrastructure of some sort, a Magus has lowest power levels in general and requires the most research but can call upon conceptual effects and the strongest among them are bullshit tier, and Parahumans run the gamut, but generally have no upkeep beyond being human.
The next vote will help determine the details of your backstory, figure out your powers, and generally give more details than the current broad strokes.
This was inspired by... a host of things. Like, inspiration, EVERYWHERE.
Edit: Fixed up some wording and grammar issues.