But how exactly would he react? I don't know much about psychology, but if he does somehow subconsciously blame himself for his abuse (assuming that he was abused), or thinks that he deserved it, how would he see someone else who was currently, or in the past, gone through it?
You're right, we wouldn't know exactly how he'd react at all, though I do think it's a safe bet to say he'd react emotionally in some way or another, even if it was to totally shut down. I don't think he'd know quite what to think of the situation--if emotionally he does in some way think he didn't deserve to be treated well, then to be faced with a similar case where he obviously wouldn't draw the same conclusion (ie, Danny would never look at a child or someone else and think he/she deserved to be abused) would probably be very jarring for him.
How exactly would that come out? I'm not sure. Anybody got a guess? I could see displaced anger--Danny would be very upset by it, which in some part would be just in reaction to the general horror of the case itself, and in part be perhaps an underlying anger about how he was treated. Just a guess, though. He could shut down completely and be totally numb when dealing with the case.