question: I've known my father in law for over 30 years. At first he was a jerk, thought it was funny to insult and belittle people, particularly his wife. For the last 8 years or so he started mellowing, being nice to people, being attentive and helpful to his wife and so on. A few weeks ago they found a tumor growing between his skull and the membrane surrounding the brain. It was on the right side of his head, about the size of a lemon. He had surgery five days ago and returned home yesterday. Now he's back being an ass again. Is this common? To revert back to a previous personality? Is it temporary?