IIRC those "principles" were pretty barebones. I think it was just the deathfog with Ifan (and Beast? Maybe Sebille?). To me, with one action that might make your team stop, you could turn altruistic heroes into self-serving sadists pretty easily.
Whom are you talking about? There were total 0 of altruistic heroes or self-serving sadists at the start of the game. All morally grey with certain ways to turn them in one direction or another.
That's kind of my point. They were grey enough that you could develop them in either direction and turn them into (almost) whatever you wanted. So Gale can be a megalomaniac wizard who, shamed by Mystra's rejection, attempted to usurp her powers, then realized the folly of his ways, and now works to protect those around him. From that point, you can develop him as a more selfless character determined to better himself and others, or descend into his possessiveness and megalomania.
