For the ask game, vampire AU where Inko and Izuku moves in a new town where there is a curfew and no one seems to want to be out after dark. The mayor, Shigaraki Hisashi, creeps Izuku out. Please.
Inko and Izuku move to a small town because property values are super-low. In retrospect they should have asked more questions about that. They just thought land was cheap because it was in an isolated, snowy area which rarely saw sun.
On their very first day, a delegation of neighbors stop by with gifts. They all very seriously emphasize the importance of the curfew. Officially, dangerous animals roam late at night. One old lady slips them a list of wealthy families in town who should be "avoided and not angered."
Izuku quickly realizes that this town is weirdly hierarchical once he starts school. A small number of children from the rich families show up in old-fashioned clothing and carry sun parasols even though the sky is eternally grey. The teachers defer to these children as if they are royalty.
A girl named Toga invades Izuku's personal space a couple times and sniffs at his neck. The principal calls Izuku to his office and tells him that he'd better find a new school. Izuku is baffled and upset because 1. There's only one school in town; and 2. He hasn't done any thing wrong.
Inko gets called to a school meeting with the principal and the mayor. (She wonders why the mayor is involved in this?) Mayor Hisashi Shigaraki looks bored, until he sees Inko and Izuku's faces, and then he switches to extreme helpfulness. He promises that he will handle Toga. Izuku gets bad vibes off this guy. Inko thinks the mayor was just flirting with her.
After that, strange things keep happening that nearly make Izuku or Inko late for curfew. Izuku's bike breaks, the clock at the grocery store is late, etc. Mayor Shigaraki shows up to be helpful when they have issues. Izuku's bad vibes intensify. To make matters worse, this weirdo asked his mom out on a date and she accepted! His mom always has terrible judgement in men so this just makes Izuku more suspicious.
Izuku does research at the library and discovers pictures from several centuries ago of a man who looks just like Mayor Shigaraki, who had a wife identical to Inko and a son identical to Izuku. His wife and son died in a carriage accident. Izuku rushes to the mayor's home to save his mom.
When Izuku arrives, Mayor Shigaraki has fallen over the table with a bite mark on his neck while a worried green wolf nudges him.
The twist: Izuku and Inko are both werewolves. They moved to this isolated town to scout it as a possible home for their pack. Hisashi wanted to turn Inko into a vampire because he believes that she and Izuku are the reincarnations of his dead wife and son. Inko had the same idea: she wanted to turn Hisashi into a werewolf because she thought that adding the mayor to her pack would make it easier to move in. Besides, he was cute and Izuku could use a new stepdad.
Before this point, Izuku and Inko had no idea that vampires existed. They knew some people in this town smelled a bit funny, but just assumed those people were sick. In fact, Inko expected Hisashi to be grateful after she bit him to cure him of his sickness. Unfortunately, vampire and werewolf venom have a bad interaction and it sent Hisashi into a coma.
Inko and Izuku flee town to avoid reprisals. They return to the UA Pack and report that this town is no good as a home. It's already infested with vampires.
Maybe Hisashi dies! Maybe he comes back as something even stronger, chasing after Izuku and Inko. I'll let the reader decide.