Welcome to my world. Neither Mac nor Ming really like Kimba and there are nights when there are the blood curdling cries and snarls and fights. What works for me is to keep a large pill bottle full of pennies or other coins near my bed. When they start in I get near them and shake the bottle hard! This breaks up the nastiest fight. They will come back at each other after a minute or so and I repeat the procedure. They hate this noise so much that after about three episodes of fight/bottle shaking they stop for the night. Hope yours stop fighting but once this behavior starts (and I've ssen it happen before with cats that had always gotten along) it's hard to stop.