Thanks to @-Jammy_Knight- The story is that Blacktooth is hunting, and a vampire cat comes and bites one of her friends, Flamefur, while they are hunting and he starts acting really weird around the other cats. Blacktooth tries to talk to him about it, but they get in a big fight. she almost dies, and so does one of her other friends who is trying to break it up, and then Flamefur bites both of them and the clan leader banishes all three of them. Then they all turn into vampire cats. =3
