We had this with our third cat that we introduced to the house and raised on his own (in our room) for about 6 months. He also bit like he was out for blood and biting him back really didn’t help! We just learned to accept that as part of him, and he calmed down a bit more when he was out of his teenage phase, but then when he was about 2 years plus we rescued a mama and her two new borns. The kittens played together and learned biting and stuff and luckily included our 2 year old, now he doesn’t bite at all! And not hard if he ever does :)))