Doctor bitch is shaping up to be a pretty evil monster.
Not sure if it's been speculated on before, but does anyone think that she and Harry missed the boat with Dexter and misdiagnosed him as a psychopath? She keeps being surprised when he shows emotion, and has started to go as far as trying to tell him his emotions aren't real.
Funny thing, is that the Dexter in the first book and the Dexter that has evolved in the show are two different animals. In the book, he really WAS empty. He described wearing Rita as a disguise. He "cared" for Deb, but only in so far as she was a tong term relationship for him. In the show, and maybe it's just Michael C. Hall's take, he really has shown true emotions for others, whether it was Rita's kids, Harrison, Deb, Lumen, Hannah, etc.
In the end, I think it's going to become apparent to Dexter that he was never what they told him he was. Not sure if the doc did it to him on purpose (to see if she could create serial killers) or accidentally. Like the way he jettisoned the whole "dark passenger" bit a season or so ago, he's going to have to come to grips with the fact that they turned him into a serial killer. When he does, he'll do the noble thing and take his own life...after offing the doc of course.
All guesses, but I think that's where we're going.