Let me say this directly: This “Dexter as a Superhero” stuff, or “Dexter is a real boy” stuff is a romantic fantasy of a dark fantasy.
First of all, let’s be very aware of what psychopathy is. Do you remember when Harry showed Dexter his brain scan? This is an actual phenomenon. Psychopathy is not a mental disorder, it is an entire framework of how a person interprets reality. For the most part, psychopaths / sociopaths cannot restructure how they interpret the world around them, all they can do is choose how they want to respond to it, and formulate their self-discipline around this decision.
Now, let’s talk about Dexter Morgan.
He has a Dark Passenger, a sentient, lizard urge to brutally reign on frustratingly lesser beings than himself. He is barely contained by his discipline.
He identifies his targets based on the electric thrill of a fellow predator.
He suffers no remorse or hesitation, so much as a psychotic and often confusing jumble of thoughts, which he constantly seeks to discipline and refine through the most horrifying ritual murder possible.
His mind is so unwrought, he imagines things that aren’t there anymore, and has secret conversations with these things while people aren’t paying attention to him.
In the books, for example, Dexter delights in pulling people open and ‘exploring’ them while they are alive. Sometimes these people meet the criteria of the Code of Harry only loosely, and he doesn’t always deeply research and confirm his targets. Sometimes he just has to kill and they are right there, begging for it.
The proper retort to this isn’t, “That’s the novel Dexter. He is different than the television Dexter, who is a superhero.” That response is incorrect – they are the same character portrayed differently, and for a number of reasons pertaining to the audience and the marketability of television versus a novel, there are some things which should not be visually depicted on subscription cable.
Some of this is documented narcissistic/sociopathic behavior – seeking to become a better human than the less-evolved, or comparing humanity to some sort of lesser, unaware, unluckily deprived beings.
The regret he feels when he violates the Code of Harry is not genuine remorse, it is self-deprecation for failing to live up to his own standards of perfection. Why would he feel remorse about removing something from the world that really had no viable purpose anyway? It is his glorious duty, his magnificent purpose as a higher being.
Sociopathy is related to a reduced empathic and emotional layers. Any displays of emotion he feels, or empathic connections he forms, are genuine. Just because he’s felt them sparingly, or doesn’t expect them when they’re there, or even doesn’t recognize them when they come, does not mean he’s any less of a sociopath.
Largely we sympathize with Dexter because he targets people who are undoubtedly deserving. We feel vindicated or celebrate his murders. He is the Bay Harbor Butcher, the vigilante who never lets a child rapist or human trafficker escape justice.
And the secret identity thing? That’s because the mass evisceration and dismemberment is inexcusable, even in the name of justice, and there is no healthy, sane human who would stand by him and watch him do what he does, and feel for a moment that he is justified in doing it.
He isn’t a superhero, he’s a sociopath and a mass murderer.