Rehab Dropout: Though Dexter was willing to give Deb's rehab idea an honest effort last week, our favorite serial killer is feeling suffocated by his sis. "I feel trapped. Like there's no escape. She's got me penned in like a aged animal, and an animal is never more dangerous than when it's backed into a corner." Oh, he's also envisioning killing lots of people: the mailman, Masuka (C.S. Lee) and a suspect in a case. (All the kills were fun to watch, no?) You know what they say: Withdrawal is a b**ch.

Dexter tries to reason with Deb that she needs to back off, telling her she's trying to suppress something that he's learned to control. She pleads with him to think about Harrisonbefore agreeing to give him some space. So of course, he chooses a new victim: Raymond Spetzler, a killer who slipped through Miami Metro's cracks. Instead of just killing him, he decides to explain to process to Deb, who promptly freaks out and tells him the law will work in the end to catch Ray. "If it worked as well as you thought it did, I wouldn't be so busy," he counters, before adding that his "lizard brain" has been her secret weapon for a lot of cases over the years and she just didn't know it.

Of course, Dex is right about Ray and Deb breaks into his house as he's about to murder his next victim (in a sick torture room that was pretty disturbing). Dexter gets there in time to save Deb, but not before Ray gets away (after murdering the girl, no less). Deb later tells Dexter she hates what he does, but she understands it. What she doesn't get? The bloodslides, which tells her he likes to kill. "I like the way it makes me feel," Dexter clarifies. Both Morgan siblings say they can't change who they are and Deb tells Dexter to move out of her house. "I'm still your brother. Nothing's changed," Dexter tells an exhausted Deb. "Everything's changed. I don't know if it could ever be the same," she responds.