Someone claiming to be a sound editor for Dexter posted some spoilers at 4chan a week and a half ago and it looks like they may be legit. I'm usually skeptical about this kind of stuff but since the first few spoilers turned out to be true it stands to reason that the rest may be true as well.
Read at your own risk!
Spoiler: click to toggle In the next episode, Dexter conspires to kill Hannah McKay, but he ends up fucking her instead. They have a fling but Dexter still wants to kill her. He does not get a good opportunity for a few episodes though because of all the other stuff hanging over his head. Isaak is sprung from prison on a technicality and continues fucking up Dexter's shit. Dexter kills Isaak in episode 10. The way he outsmarts Isaak in the final hour is one of the most humongous asspulls in the show's history, but the show redeems itself with a table scene that rivals Trinity's, seriously one of the best Dexter scenes ever. Episode 11, Dexter finally gets the chance to nab Hannah. Except when she's on the table, right before he kills her, she tells him that she's pregnant. With his child. Finale, Dexter confirms with a pregnancy test and isn't sure what to do. he puts her in a cage a la Doakes while he decides. She pleads with him to let her go and pledges her love to him and the unborn baby, but he doesn't buy it. Season cliffhanger is La Guerta cracking the Bay Harbor Butcher case. She figures out that Dexter is the killer. To keep her silent, Debra kills her. Dexter walks in on her doing it, much the same way she walked in on him. Doakes does appear in the finale, but only as a manifestation of Dexter's subconscious. He says "that line" ("Surprise motherfucker!") and gives him shit about keeping Hannah prisoner. http://25.media.tumblr.com/tumblr_mcxmosIqQu1qhs1v5o1_1280.jpg | 
6:36 AM May 24