Your elders have raised you to hunt vampires, as according to them, vampires have no morality in them. All they wish to do is feed. You are hard wired to hate these evil creatures, until you meet one and learn the truth. They only drink the blood of those they want to mate with, marking their territory. This information catches you off guard, especially when you realise a vampire has been watching you for a while now, just watching from afar but never making a move.