Mine also constructed a two-cat social hierarchy (yes, there was an "outcast" and the "accepted" cat, lol). We got rid of the oppressive kitty at Christmas, who was moodier but more social, and the recluse who is lazy and pees everywhere and has diabetes became much more social. Sad thing was, the stronger cat was the recluse because she was bigger. XD;
The oppressive cat apparently just hates other cats, though, because she loathes the other cat my grandma has.