Thanks for the suggestions. I have come to believe that my cat is the spawn of satan..and I still can't love him any less. lol

Is it possible for a cat to just have a horrible disposition? If so, I think I have found the king! The other cat isn't actually getting into my home..for the most part. Kind of difficult to explain, but he is getting into the heating vent and fighting with my cat through a floor grate. They don't actually have any physical contact between them, just a lot of growling and hissing!

Again, I appreciate your suggestions. Any insite I get on him.. is better than nothing.
Thanks