well, my protagonist is a cavalier with a CHA of 17, the party has an excellent reputation. but i can't seem to be able to get Balthazar to join me. i have tried many combinations of speech options, but none seem to work.
if you want balthazar to join you, you have to be good overall in the whole game, with probably a high reputation. you will notice if you were "good" by talking to balthazar and saying "im a force of righteousness", he will say something like "i know". little confusing?