My two cats are brother and sister and are three years old. They were best buds up until two months ago. There was a huge fight that we thought was caused by female redirecting aggression after seeing neighbour cat. However, now it seems like male might be the aggressor. Usually happens in the same spot. We have done the reintroduction thing went ok for two weeks then fight happened again. The femake is on meds. They can both be fine and together all day and then all of a sudden they gave a stare down. We have been abke to stop it before ut escalates but its stressful. Help.....