At heart, All Vampires are Monsters

In this world vampires are a strong, but dying bred because you can't give birth to the undead. So every year or so we host a party of sorts to keep our numbers up. Inviting humans that realize that life as a lowly human isn't enough for them and want more. But just because they want to be vampires, doesn't mean we'll let just anybody join our kindred. So they become contestants in a game.