Sociopaths will manipulate anyone. Let me repeat that. Sociopaths will manipulate absolutely anyone, including mom, dad, brothers, sisters—anyone. One way that this happens is the sociopath gets his or her family—knowingly or not—to participate in the victimization of the target.
One thing that I do believe should be approached about a sociopath is his ability not only to control his victim, but also his family. The sociopath works his family to the extent that he manipulates his immediate family into believing that none of his problems in life are his fault and consequently the blame falls on the one he wooed into a relationship. In this manner he deliberately cons his family into enabling him in his behavior.
Other times, the family members are sociopathic themselves—the risk of developing this personality disorder is genetic. So they see absolutely nothing wrong with predatory behavior.