You know, if I suffocate B in his sleep, I could have all the water. . …
Getting back to the OP …
I was blanking on the personality disorder where someone is contrary despite their best interests. So far, the only thing I could find is oppositional defiant disorder but that is supposedly a childhood disorder. An adult with those problems is likely to just be labeled with antisocial personality disorder, but I think the oppositional label is more suitable. Also note that this disorder involves a lot more issues than just being contrary.
Who said something about going home? -Hitler.