Biting is instinctual. While in early infancy biting is rather exploratory, toddlers bite when frustrated, angry, or tired. If I have to deal with a chronic biter, I must use a sensitive but strong strategy. Both ‘victim’ and ‘aggressor’ need to feel that the adult is in charge and can protect them. I say to the biter, calmly but firmly, ” I will not let you bite any child or big person. If you feel like biting, here are things (teething rings, rubber or plastic objects, etc.) you can bite.”
I watched him very closely in order to predict what would trigger his aggressiveness and prevent him from doing it. I would hold him firmly but not punitively, telling him that I would not let him bite and that he needed to learn to trust me.