Unfortunately, not all new additions to the family work out. As much as I love Specs, I should have rehomed him when trouble between him and Boo first began. Poor Boo Bear, once alpha male, is 16 now and Specs, approximately 7, still aggravates him. It isn't as bad as it was when he first was introduced. Specs terrorized Boo and since he was an outdoor cat all along, I tossed him outside once because he beat up Boo so badly. But he came to every window of the house, hung on the screens, cried and cried until I relented. Now he just follows Boo, they don't fight any more. They even sleep together now but I think Boo just tolerates that and prefers to be left alone. Specs can be a little punk, pure and simple, but he can also be very sweet. I put Boo through hell and I shouldn't have, all because I felt that once I took a cat in, it should stay. If you feel there's any chance that your two can get used to each other and work it out, then maybe you can wait it out. If not, start working on finding Tuscan a home now because it's only going to get more difficult to part w/him, even as upset as he's making everyone. I'm sure he'll make someone a great companion but he may need to be in a one cat household. Don't punish yourself for this and especially don't punish yourself by keeping him if you know in your gut that it just won't work. Been there and I'm w/ya.