Sociopath or not - he's a good character to have in the show as a lot of the action plays out around him. I personally think he's a ticking time bomb with his growing propensity for violence. Let's face it, he made have good intensions but the fact that he lined up Rick in his sights, nearly went postal at the CIC, barely restrained himself in his attack on Lori, sacrificed Otis, threatened to kill Dale and then really blew up at the barn scene. He wants to be a good man and a role model for Carl and wants to have a relationship with Lori but he is way too volatile. That will come in handy as he will explosively react with the other characters. He is like a barely restrained and once tamed wolf going back wild. One of these days he and Rick will "have it out" and a season cliffhanger will be born!