Anyone who writes crime fiction, especially novels about a serial killer, is familiar with the sociopathic personality. But not all sociopaths are killers. Some psychologists estimate that there are thirty thousand psychopaths who are not serial killers for every one who is. So who are these non-killing psychopaths? Your neighbor, perhaps, or your mother-in-law. Maybe even the psychologists who came up with the sociopathic profile. Possibly even you.
Abused children who were not born with a sociopathic personality usually grow up to lead normal lives. Sociopaths who were not abused usually grow up to lead normal lives or lives that mimic normalcy. Sociopaths sometimes become killers because of childhood abuse, and sometimes they become killers simply because they want to. (The killer in the Dutch version of The Vanishing was a classic sociopath who killed to see what it would feel like.)
Even if you don't write crime fiction, familiarity with the sociopathic personality can help you create dynamic characters and even interesting dialogue. For example, sociopaths frequently use contradictory and illogical statements such as "I never touched her, and anyway, she wanted it."
A sociopath has difficulty connecting to others, though people often like them. They are charming, glib, witty, and use captivating body language. Because of their impulsiveness, need for excitement, poor behavior controls, and lack of responsibility, they can be fun companions, but because they lack empathy, conscience, and remorse, they can never truly connect with anyone.
Other characteristics of the sociopath are shallow emotions, egocentricity, lying for no reason, no need to conform to societal standards, the skill to detect and exploit the weaknesses of others. They are also well satisfied with themselves, never looking back with regret or forward with concern.
One characteristic that keeps a sociopath from being a good fiction hero is that in fiction heroes need to change during the course of the novel, and sociopaths have solid personalities that are extremely resistant to outside influences. But, being the manipulative creatures that they are, they can make us believe they have changed.
Sounds to me like an interesting character. With or without the killing.