So my husband and I adopted sibling cats 5 years ago. They are brother and sister and have been together their whole lives. Since adopting them, there has been no major changes. About 2 months ago, they started fighting. So much so that they both have scars on their faces from it. We found a cat behaviorist who came to the house and gave us some advice for a couple of week. We followed what she said but now we are on our own. They were seperated for about 5 weeks until we gradually started slowly introducing them again. Last week (week 7), we decided to let them roam free while supervised and everything was going great. Since then we have had two set backs. One was laat night when we decided to leave them out overnight. No fight happened but alot of growling and hissing. Same thing happened tonight but worse. No fighting but if we weren't home, im sure there would have been. They have both been to the vet and tests show no illnesses. I think the male cat is the aggressor and the female cat is extremely stressed and scared. I don't want to have to rehome one of them but we can't keep allowing this to happen. Not fair on them or us. Any of this sound familiar to anyone or does anyone have any advice on how to work with them to being friends again? Thanks!