I own nothing
Also, this is kind of inspired by the brilliant game: Alan Wake (not a crossover though)
Old Days and Broken Dreams
One month ago, the city of Zootopia was a paradise. Speciest tensions were at an all-time low, unemployment was down, and crime was virtually non-existent. But that wasn't all. With the new-found relationship between predator and prey the city flourished. The city's revitalized economy drew the attention of many around the world. One group in particular held an affinity for the city: The World Games Council (ha ha discount Olympics). They noted everything about the grand metropolis; from its diverse populace to the advanced environmental control infrastructure. They decided that Zootopia would hold this year's games.
When the months of the games came around Zootopia became even better than it was before. The average man became rich, and those who were already rich lived like kings. Life was a dream.
But as some dreams do: this one became a nightmare. It happened one night, the natural darkness of the late hours came to life. Twisting and writhing like a dark beast. It devoured all those who were not protected by the light.
The next night, the darkness returned those it stole. However, they were not the same. When they returned they did so as husks of their former selves. The darkness clung to and penetrated all whom were taken by it. The Dark Ones tore across the city, killing all they could find and pulling them back to the unnatural darkness. Then the sun rose and dispelled all traces of the monsters from the world.
The next night they returned and the ZDP tried to fight back, but the darkness protected its thralls from conventional weapons. The sun rose but the Dark Ones remained for nearly an hour after it had risen.
The night after, the same thing occurred. And again they remained after the sun had risen. This time for four hours. This pattern continued for until they simply stopped vanishing. Soon the Dark Ones outnumbered the untainted citizens of Zootopia by twenty to one.
At night they were smart, coordinating, and invincible. The only defense then was warding them off with light. In the daytime, they lost their intelligence, their coordination, and their protective shells of darkness were burned away; making them vulnerable to conventional weaponry. In the day, you had a fighting chance.
The world had changed from one of frivolous necessity to one of survival and responsibility. Every day, people fought for what was left, and at night people prayed that the Dark Ones didn't get them.
Four factions had risen out of the ashes, each of them fighting for whatever they could find. The Forgers: a group of construction workers operating out of a fortified job site. The Legion of Light: a zealous cult that controls the Zootopian Solar Plant. They demand a daily tribute of food and medical supplies in exchange for supplying power to the other survivors. Ryan's Released: a group of escaped convicts that have claimed the streets, they operate out of an old apartment building and are by far the largest group. And finally, we have the Zootopian Defense Force: they were formed by the remnants of the ZPD and people who wanted to restore order to the city.
Every day was a war. If you won you got to fight it all over again, but if you lost…you joined the unholy brotherhood of the Dark Ones. Every moment of life was a moment they stole from the Dark Ones. For most people, this was enough reason to keep going.
Sorry if this intro reads a bit sluggishly, I'm experiencing a slight bit of writers block. On the bright side I won a vacation to a little town in Washington called 'Bright Falls'. It sounds relaxing.