I've also seen different cat behavior when I'm in the room vs. when they think I'm not looking.

Sid and Joxer are my two classic examples. Joxer is the submissive one, he'll approach Sid, lower his head, and act all subservient, at which point Sid baps Joxer on the head and hisses at him with a look of disgust.

Later, if they think I'm not looking, I can find them playing with each other, like they're best friends. I can't let Sid know that I'm looking though, or he gets self-conscience and the game is over.

They're so funny

And that's just one set of dynamics! I've noticed that the cat dynamics seem to go in pairs, so I have the following:

Sid & Jan
Sid & Joxer
Sid & Quincy
Jan & Joxer
Jan & Quincy
Joxer & Quincy

I could write an essay on each pairing, because the dynamics of each are unique.

I love my kitties!