I say for teh most part You got the 'role's down pat.

the only thing that I disagree with is having your Brute also be your sneak/socail face.

that is, to me at least, the opposite of what the Brute 'role' is all about.

I would make the Dark Chick a courtesan, have her be the 'inside man' for the Dark Genius. seducing other rulers into doing what teh Dark Genius wants. Chaos, wars, etc. And when he seduction attempts fail well, she is highly skilled and very precise. to use your Avatar example. the fire nation princess. Mostly without emotion, very cold, calculating and highly, highly skilled. oh and she would be some type of assassin (not forcing the prestige class on you, that is a huge gripe i have about 3rd ed but that is a rant for a MUCH later time) Good at getting in getting the job done and maing it look effortless less. also she would be 2nd in command.