First of all, since you were bitten on your leg on your boyfriend was bitten on his hand you may need to see a doctor if Havoc bit through your skin. Cats mouths contain a lot of bacteria which can give you an infection and you may need to be put on antibiotics for this. When my RB Starr bit me on the hand very hard I had to do this just to be on the safe side.

I agree that Havoc probably smelled the other cats scent and then he decided to lash out at Toby. Cats noses are very sensitive. I don't know why he wasn't bothered by it until later though. My cats in general will all get along but they also have their squabbles too from time to time. It's usually nothing major but I do have to break up some fights sometimes and I'll put Storm,who is the alpha male, in my bedroom for a while for a time out. I hope that your boys will be able to at least tolerate each other from now on. Good luck.