He changed, he turned to pure evil one sudden day and using red smoke from his mouth to put people/the other critters to sleep which makes them insane. You never liked him, although you and him were both cats you found him twice more creepy and tended to avoid him while it seems he hated your guts, one day he walked into the living room and sprayed the red gas on everyone but you managed to make escape and now he was chasing you down with loud roars that surprisingly didn't wake anyone up.