Vampires and Werewolves were natural enemies, always fighting over territory.

You growled at the vampire, you, who stood covered in blood in front of you. "You're hunting on my territory, you freak-" You was cut off as Mathew made eye contact with you and your eyes flashed pink for a brief moment. You face fell in horror, and he took a few steps back. "This... this must be a mistake..." *you muttered, horrified. You just mated with a vampire... *