But that it just the thing: You DO change things for the three mentors, just not for the better. And while that makes sense in Markus' case (he wants to show his "apprentice" the truth, which kicks off the attack against him), we are offered no such reason for Heath and Randal. If you don't pick them as your mentor, they are not shown to take an unavoidable turn for the worse. Of course one might argue that we are simply not shown, but on the other hand you can end the game by Randal's side, even if he wasn't your mentor, and it is never mentioned that he becomes withdrawn and disheveled - something that definitely should draw attention if you are his second in command or vice versa. I admit that I dislike stories where you can "fix" people with deepseated issues just with the power of love, but I'm not fond of this forced nosedive as well.