That's a little sketchy for details. What do you mean the cat is being mean to it's housemates? Is it attacking? Is it just swatting? Is it biting? What starts it? What steps do you take to stop it? Have they been to the vets or separated lately for any length of time? A complete history of what/how/when/why would be helpful in order to give you the assistance you are requesting.
Assumptions do nothing but make an ass out of u and me.
We can stick our heads in the sand for only so long before it starts choking us. Face it folks. The pet population is bad ALL OVER THE WORLD!