In this world, there are two species such as Vampires and Werewolves. Bill is a vampire while y/n is a werewolf which makes them enemies.

One night, on a full moon bill finds y/n thinking that she is just a big dog he decides to take y/n home with him, not realising she is just in his wolf form and is actually a werewolf.

the next morning, bill woke up only to see that the wolf he thought was just a big dog, was actually a werewolf snuggled up with him in his bed.