I was playing with two separate pairs of cats last night at different friend's houses. I realized that when you have two cats, you always have one that's social and one that's not. One that is fat and one that is skinny. They can be any combination of those binary options, but that's pretty much it.
I also had an epiphany that most (but luckily not all) cats act pretty much like jilted lovers. They want to show you that they do not need anyone else in response to some hurt they received in a former life. The try and make you want to play with them and stroke them, but they will not show interest in you unless you are showing your own interest elsewhere. Then, when they do give in and ask for attention, they may lose themselves in a moment of enjoyment, but the second they realize that they let themselves open up to you, they slam the wall up again, scratch or hiss at you, then run off, just to prove that they operate independently, and it was in fact you that needed them, and must try to win them back.
Either that or I'm projecting.