One of my cats, Mouth, is a very nervous cat. Doesn't like to be touched very much, except by me and my husband, and tends to hiss at strangers. I usually just warn people away from him and let him take his time deciding if he wants to be friendly. Yesterday though he went nuts! I had my mother, sister and her two children over doing some work on my house. Mouth knew them all from previous visits and such (if a cat's memory is that good), and they had all been over Friday and Saturday as well. I don't know what got into him but all of a sudden he just attacked my sister! He bit the heck out of her ankle and then jumped on her back scratching and biting. I got him off of her and calmed him down pretty quick. I sent everyone outside until I had him in another room and calm. I left him and his brother in the bedroom until we were done for the day; packed his food and water and the litter box in there with them. The only thing I can think of is that he got too stressed and just snapped. My sister was a good sport and wasn't hurt too much and after a while we sort of laughed and said I have my own little attack cat. ;)