This new guy seems pointless too, purely a plot device thrown in to progress the Hannah story.
Hm, not sure it's just that. He already basically told Deb that Dexter fecked up and she'll most likely - correctly - think it was deliberate. Beyond that, let's see what he knows. There seems to be quite a few opportunities with the vast research he does, but you never know what it develops into of course - if anything.
When they are talking about heart disease, why does Harry say to Dexter "Hell, it got me"? I thought he commited suicide...
Yeah, I found that very odd as well. Poor memory from everyone involved it seems.