A stray showed up at our house a few months ago and being a cat lover I fed him. He never left and started hanging out on our deck. When it started getting colder I decided to have him neutered, shots and tested so he could live inside. We currently have two female cats who have never liked him since they first saw him outside. When I first brought him in he stayed upstairs for a while and eventually started feeding them on opposite sides of the door until it seemed like they could tolerate each other. He never once showed aggression towards the girls but he would do this whiney cry as if he wasn't happy. I noticed once I started letting him downstairs that he would fixate on the girls. He would sit and stare at one of them until eventually he would try to attack them. I tried diverting his attention with a toy when I saw him start to obsessively stare on one of them but he would go right back to staring. Fights started happening with him being the instigator. It was always a "drive by" type of attack until tonight. I made the mistake of leaving him unattended with the other cats while I cooked dinner. A fight broke out and now one of the girls has a puncture wound on her ankle. I've never seen a cat obsessively stalk another cat like that. I understand that he's a street cat and that's probably how he's always survived but I don't know how to change this behavior since he's probably over a year old. He also has other obsessive traits like licking me or my husband. It's like once he gets started he can't stop. He's needy and needs to lay on someone at all times. If I get up he has to follow and be under my feet. I've thought about trying to get him adopted into a new home but I don't think he would have high chances of finding one. He's such a sweet lap cat but is like a Michael Myers to the other cats. I don't want to just give up on him but I don't know what to do.