Bjørn-Sigurd (Uncle)

Maria's brother, Mort's uncle, and the leader of a tiny local vampire slayer club that almost nobody actually takes seriously besides him. It's not like they've actually managed to slay any vampires yet.

So yes, he absolutely hates vampires for some reason. He wants to get rid of them forever to protect people from their harm, because he believes they're all inherently evil and only want to hurt mortals. 

However, he also cares about his only nephew. He never had any children on his own, so Mort's the closest he's got to a son. You could imagine the conflicted feelings when said nephew accidentally becomes one of them.