Lukke is your friend. He never did anything to you that could hurt you. Lukke is a vampire. Vampires tend to be bloodthirsty, he just didn't kill people when he sucked blood because of the waning moon. until during the night, you see your bedroom window open, and you realize that Lukke is thirsty, he is entering your bedroom.

Lukke: I need you he says in a thirsty voice