yeah, see the loss of his mom when he was really young, and then the stuff that followed sort of make it make a little more sense now...right? (i'm not saying it ties it all up in a happy bow) but it just makes it a little more understandable as Justin.
and learning for the last year and a half or so to live without any affection because emotional damage is worse...well, that colors a lot of how justin responds to people.
I don't thing Brian's ready to give up on him yet, every time he does, he finds some small reason to hang on.