Thread:TVfan99/@comment-6554265-20140420000424/@comment-24819071-20140420005143

Okay, this is sounds very straight forward. His behaviours are consistent with a personality disorder. I rule out borderline personality disorder because there is often extreme anger and rage, a terrible fear of abandonment, excessive attention-seeking, persistent manipulative behaviour to achieve their own ends (often related to gaining sympathy, nurturance, or love), marked impulsvity, self-harm, and although sadism, narcissism, and  lack of empathy are borderline traits, he just doesn't meet the criteria.

Narcissistic personality can also be ruled out due to the apathy you describe. Narcissists display evil tempers, they've got a temper like a cobra. They are almost always above average in intelligence, which your character is not. They are demand attention, but in the narcissists case, it has to be positive/flattering attention. Unlike the borderline, who will take any sort of attention, positive or negative.

My guess is your character suffers from antisocial personality disorder, but he has sadistic features. He also suffers from sexual disorders, or paraphilias. Not sure what specific paraphilia, but it's likely several that he has. He's a sadistic sociopath, with sexually perverse tendencies and habits. It's what it sounds like to me.