The fact that in his personal quest he says he is tired of running, as in he has just now decided to face the music. This is the man who was so afraid of facing his past that he stole a Warden's identity, depriving the Warden's family closure, rather than using his own name in a nation that is no friend of Orlais so wouldn't even be looking for him.
Tired of running from himself perhaps - and he does want to deal with it; maybe he couldn't really face up to it until spending time with the Inquisition and seeing himself as you see him (in a romance anyway). Sure, at the start, he has been a criminal on the run, atoning in his own way (like helping those fishermen out), but he's also a man with a guilty conscience, and his guilt has clearly been weighing on his conscience for years upon years now.
Also, he wasn't afraid to face his past when he took on Blackwall's identity, in my opinion. I will just point out that he was recruited by Blackwall and that he was right in the middle of collecting darkspawn blood for the Joining to become part of the Order - it's jut that things went awry and the real Blackwall seemed to think enough of Rainier to save him from a killing blow. Additionally, I will point out where Rainier effectively said that it was a waste of a good man's life - better that Rainier die and "Blackwall" continue on. He was simultaneously honoring Blackwall in his own way and atoning, but he wasalso still hiding from the law - not going to deny that he was.
As for that other thing about being disappointed in the companions, you should recognize that they all have their own flaws/secrets/issues/failings and that some of them, perhaps, feel that they shouldn't be judging other people in such black-and-white terms. *shrug* It's fine to not like what he did, to not forgive him for it if that's how you feel, but I think you shouldn't try to make out as if there are no consequences for his actions and that the companions aren't entitled to deal with it in their own ways. If they understand and forgive, then they just do.