Hmm. I think that inconsistency was to have been explained by the domination that Zack supposedly was under by the "master". If the master was someone whom Zack came to see in higher regard than Brennan, he may not give her such an opportunity.

My problem is that I don't see Zack as being that type of weak-minded. Zack has never struck me as easily lead and the master was not presented as being massively charismatic and persuasive, except by backward reasoning (Zack was persuased so the master must have been persuasive), which isn't very convincing.