Therein lies the problem. This should not be the kind of revelation that sets up two full seasons. I really think the series would have been better off had they gone straight from season 4 into a scenario where Deb finds out about Dexter with a couple of episodes to go in season 5. Then they should have finished off the series right then and there with a couple of hours of pure sh|t storm. They've already screwed it up beyond repair, in my opinion.
This confused me as well, and just seem awkward throughout the entire season. The only thing I can come up with is the guy figured out that Dexter was a serial killer himself. It'll be interesting to see what the different marker colors on the palm of the fake hand were for. Overall the characters of the baby sitter and the intern dude just felt really out of place... the same goes with Quinn's fall.
