I just recently finished a book trilogy written by Dan Wells, "I Am Not A Serial Killer", "Mr. Monster", and "I Don't Want to Kill You".
I felt like this series was something I had been looking for my whole life. The main character is a diagnosed sociopath, whose town is plaqued by a successive series of serial killers (of a most unusual nature, even for killers). The series could have been a sick, erotic, piece of work taking the worst of humanity and rolling in it. I don't care for such works. I like a certain amoun of "grit", but my tastes are more aligned with, say, The Dark Knight rather than the Saw series. However, in this book series the action and gruesomeness was laid out with taste, style, and a certain measure of restraint rather than pure slasher-film titilation. In addition, the main character, John Wayne Cleaver, was not only likeable and sympathetic, but quite possibly the most heroic main character I have ever seen in print or on screen. He is a person who has, due to his sociopathy, virtually no easy motivation to be a good person. He has no empathy for other people, and he has all the main signs of a serial killer, minus actually killing people (fascinated by fire and the torture of animals, comes from an abusive background, etc.) It would be as easy for him to become a monster as it would be for a person to get addicted to cigarettes.
Yet, as hard as it is for him to do the right thing, and practice self-restraint, he does it anyway. He does not let his dark desires become his destiny. In fact, he ends up using his sociopathy for positive ends.
Like I said, I like a certain amount of grit, yet many of the books, movies, and TV shows which lean towards the dark side have elements that I wish were not in there, that would cause me to look away in repugnance (to keep from staring in dark fascination), or not consume the work at all to begin with. But this series, for me, had a virtually perfect balance of promoting wholesome goodness, while still acknowledging, and educating on the darkness. Anyone who likes to at least look at the edge, without actually standing on it, should check this series out.