Dexter always comes close to showing real, genuine happiness when all of his problems no longer exist. At the beginning of season 8, LaGuerta is dead -- and not even at his own hands.
That means he has no one looking at him as a "psychopath" anymore (words used in his direction in the episode), not even Batista, who quickly dismisses warrants and trace requests for Dexter and Deb found in LaGuerta's personal items as just Maria's way of refusing to let go.
Six months after the death of LaGuerta, Dexter would appear to outsiders as happy -- he's coaching Harrison's soccer team (Harrison's now talking up a storm), gotten the bowling team back together and is even dating (or at least sleeping around) once more.
Batista's retirement does not last long. As now, with LaGuerta's death, he wants to "do nothing but chase bad guys."
He also is oblivious to all of what LaGuerta uncovered--as well as the fact that his sister Jamie is now sleeping with Quinn. (Though, in Batista's defense, no one has caught on to that fact, though Dexter comes close in one moment during the premiere.)
He seems to have settled into Deb's former role of being in charge, and while he quickly dismisses LaGuerta's suspicions, the fact remains that he's continuing to go through her personal belongings, meaning he's bound to uncover some additional evidence at some point. (Perhaps the tape of Deb at the gas station?)
A New Killer
A new season, of course, always does seem to bring about a new serial killer -- or so we suspect -- in Miami. This one likes to scoop out part of their victims' brains after they kill them. It's a disturbing and unusual enough behavior that a neuropsychiatrist named Dr. Evelyn Vogel is brought in to assist the department.
Vogel, known as the "psychopath whisperer," apparently arrived in Miami "out of the blue." She quickly walks the department through her views on psychopaths and even tells Dexter later that she believes Doakes, who she claims she thought was the Bay Harbor Butcher, clearly had "guidelines" when choosing her victims.
It's all a smokescreen, however, as she confronts Dexter at the end of the episode with a series of bloody drawings he made as a kid. When Dexter threatens her, she reminds him, "You can't kill me ... because I don't fit Harry's code."
Did Vogel discover the code Harry instilled in his son? Or was perhaps Vogel, with her medical knowledge of a psychopath's brain, the very first person to suggest such an idea to him in the first place?
Seems like that latter -- but that doesn't explain Vogel's presence in Miami, unless she's there because she thinks Dexter broke the code for the first time -- meaning she thinks he killed LaGuerta.
While Deb remains a danger to Dexter -- she at one point tells him, "I shot the wrong person in that trailer" -- she also remains a danger to herself.
She resigned from the police station and now works in private security. While in the process of tailing the jewels that a recent mark, Briggs, had stolen, she did cocaine, slept with him and made an impression on Brigg's would-be assassin (who stares menacingly at Dexter after the cops show up from a 911 call Deb made when Dexter killed him in self-defense).
All episode long, Dexter tries getting through to Deb because he believes she is lost without him. She's disappeared and letting voicemails pile up. She's being reckless. She's spiraling out of control.
"I am in some f****** shitty hell -- which is what I deserve," she tells him, "But you ... you are lost."
Deb says she can live without Dexter, but she says he can't live without her. While Harry gave Dexter the code, perhaps it was Deb all along (subconsciously and then last season, consciously) that convinced him to follow it.
Without her in his life now, who's to say what code he will or will not follow?