Was he unstable? My Dad was fucking weird in the worst way possible, and I usually like weird people. His moods would switch from being overly positive to then screaming at me for no reason, and he put his wife before me, never treated me fair. He was an utter snob too. Even as a kid he would send his wife around to my house to have a go at me, even when I was only fifteen. He was a real wimp but bullied me terribly.
If he saw me now he'd probably be intimidated by me, back then I was really fat and timid.