A lot of speculation ranges on just how well-intentioned and trustworthy he really is, which is fair since, being the leader of the Reapers, he's responsible for countless genocides. There's a rather fair amount of this in regards to the Catalyst.Incidentally, this would also bump Kai Leng down from The Dragon to The Brute. If he is indoctrinated, then he gets demoted from part of a Big Bad Ensemble with Harbinger and the Catalyst to being a Dragon with an Agenda or worse, the Evil Genius to the Catalyst's Big Bad and The Dragon to Harbinger. This causes some debate over how responsible he is for his own actions if he wasn't indoctrinated (or at least not enough that it could be called More Than Mind Control), then he did a running leap over the Moral Event Horizon a long time ago. The novels suggest he's been subtly indoctrinated for the last twenty years, where as he didn't get fully enhanced to Saren-levels until fairly late in the game. Most of it comes down to when he was indoctrinated.
