2kitties said what I would have if I'd have thought of it. They may fight like cats and dogs at first, but only to find their place in the heirarchy. And it is not always like that. My very first two were like that. Brining in #2 when #1 was a loner was just like the biggest mistake i've ever made, but they became more inseperably than any other two cats I've ever had. 2 kitties I wish you'd talk to moosmom, she may give up on her new cat Boo because of the fighting. See cat rescue "black stray kitty" (sorry, I don't know how to post a link)