"Big" Jim Rennie is a used-car salesman, town Second Selectman, and the head of the country's largest methamphetamine distribution. To himself, and to others, he rationalizes away his sins by saying what he does is always "for the good of the town". Even the murders he commits is part of the greater good, including the smothering of his late wife. She was in pain and going to die anyway, Rennie thinks to himself. The other citizens he kills to cover up his other crimes, as they were the two people bent on exposing him. Again, Rennie believes he killed them for the greater good, because he is the best leader for the town. A leader can't lead from jail, now can he? Though Rennie swears he only deals meth to raise money for the town and strengthen the business district, the only businesses he props up are those directly linked to him or his co-conspirators. Theoretically, Rennie can retire on any beach of his choosing, considering the millions he's made for himself. Yet, on a beach, Rennie would become just a man. By staying in Chester Mill, his supposed talents are put to good use as Second Selectman. What makes Rennie a more realistic character is his heavy Christian background, and his love for his son, Junior. Even as he snaps the neck of innocent women, Rennie does not forget to thank the Lord Almighty, or tell his son he loves him.
Junior Rennie is another great antagonist in Under the Dome. Unlike his father, Junior does not want power. What Junior wants is an abatement to his chronic migraines, which he does not know are caused by a brain tumor. In part, his migraines (and tumor) are to blame for his bad behavior, but then again, the apple does not fall far from the tree. Junior murders his fair share of people, even keeping them in a pantry to visit and sleep with, calling them his dead "girlfriends". As mentally ill as he is, Junior is able to recognize his father's own disconnect from reality and remarks upon it: "Dad, has anyone ever told you that you're crazy?" Junior is also smart enough not to take part in the gang-rape of Sammy Bushey. There is also a point in the book when Junior does a genuinely good thing; he and a fellow officer rescue two abandoned children from starvation. When one of the kids wrap their arms around Junior's neck in gratitude, he thinks that he has never felt better.
Rennie and Junior's characters are reprehensible, but they are also human, and their depth leaves room for the reader to hate and understand them at the same time.