My cat is mental he will be nice one minute and the next and grapples on to my arm and bites,then he will let go like he knows its bad and lick u,also he stalks one of my other cats and corners him and beats the crap out ofhim every night, I don't know what to do is there anything I can give him?

Has he been neutered? That might be the crux of his aggression problem.

Is he declawed? That could also be a trigger.