He not only kills his nosy friends - or his wife's nosy friend and her husband - but driven by a keen logic and survival instinct, soon kills his own wife. His "gift" to her, as he tells her as she's slipping into unconsciousness, is that she won't be aware when he's cutting her apart. He tells her and us that he enjoyed "playing house" with her, but he needs to move on, as he has done so many times before.
Significantly, he spares his children, leaving them unconscious but fully alive and revivable. Why? Well, he likely thinks that they have no information about him that can help Ryan. But how can he be sure? Possibly he has some scruples about not killing children, especially his own. Maybe the thrill he gets from killing has to come from killing adults.
Meanwhile, Ryan has a good evening, insofar as he throws out the doctor at his dinner table when the doctor starts lecturing Ryan about capital punishment. I actually agree with the doctor, but Ryan not having any tolerance for such a lecture at a time like this is very much in line with his character and good writing. So is Gwen's frustration with Ryan, and his slowness in bringing down the wall of his thorny exterior. Their relationship is one of the best aspects of the season. (And I still can't help being a little suspicious that she might a someone's follower herself, obvious as that might be.)
The capital punishment discussion is occasioned by Joe, who has just a few days of life left on death row. A part of me wouldn't mind if Joe's indeed executed, and Theo becomes the new continuing cross-season villain. But I have a feeling that won't happen.
In any case, Theo has breathed new nasty life into this season, the second part of which has been much better than the first, and I'm looking forward to more.
And see also The Following Begins ... The Following 1.2: Joe, Poe, and the Plan ... The Following 1.3: Bug in the Sun ... The Following 1.4: Off the Leash ... The Following 1.5: The Lawyer and the Swap ... The Following 1.7: At Large ... The Following 1.9: All in a Name, Or, Metaphor in the Service of Murder ... The Following 1.13: At Last Something of a Day for the Good Guys ... The Following Season 1 Finale: Doing Dead
Like a Neanderthal serial killer in the current world? Try The Silk Code