I had this partner who would hold grudges against people who made better scores than him in certain hands. It wasn't exactly like having a nemesis but he would say after finishing a round 'well we got the two boards and that lady owed me' or 'this lady got me again, we'll see about that the next time'. I confess there's some people I fear when I'm at the table against them. Usually disciplined people, the who wouldn't go for a number by making a silly overcall like I would.