Vedran, keeping Anomen is indeed possible, whether he failed his Test or not (you've just got to be very careful what you say to him after he fails). His romance seems to be pretty straightforward, but his non-romance quest (his dealings with his father and Saerk) is a nasty one.....the gods really have it in for Anomen.
In one of my pervious games, I ran a Neutral party and kept a Chaotic Neutral Anomen all through ToB....it was fun to hear him talk about the pompous jerks he left behind at the Order, and was very glad that I'd helped save him from such a fate.
