I think that whenever you have more than one cat in a household, you might have fights. There is always going to be a dominant cat, as far as I can understand, and often there are ongoing fights over dominance - even in cases where the actual dominance situation never changes. They willl still fight it out - with the dominant one emphasizing that she is stilll dominant, or the underling making a play for dominance. It's just normal cat stuff. I have also read in books by cat experts that it is much better not to interfere with cat dominance wars. They will have to sort things out by themselves. Obviously, if someone is really getting hurt, you will have to intervene somehow - but fortunately, I have not had to deal with that situation. Mine seem to haggle and bite and wrestle and chase sometimes, but mostly they step around each other and let things be.