I couldn't begin to imagine the outrage if we were suddenly just a grunt, and were expected to do what one of the other party members wanted to do instead of playing the way we want.
You have a big influence already by choosing who you want to take in your group. What point is there in having an evil companion if everything he does when you act again heroically and selflessly is grumbling and standing in the corner? Would paint a pretty pathetic picture of an evil companion if you ask me...
