I have raised a scrappy 1 year old black domestic cat from 3 weeks old who has a strong hunting instinct, he likes to go outside and has even brought a mouse home. He play bites very hard but does not break the skin. He started biting like this since he stopped bottle feeding. He gets in frisky fits where he attacks his own and other peoples limbs for no reason. We had an older cat, that he often tried to jump on and play with. She did not like this so she would often stand ground and hiss and growl at him, and he would stand down, but when she turned to move away from him, he would chase her and pounce on her and the ordeal would happen all over again.