My DS 7 always seems to end up fighting with his friends. Whenever we have someone over to play, I feel like a referee constantly trying to keep the peace. They can be playing nicely then it can end in one of them moaning and getting upset over such little things. He said this, he said that, he won't play etc etc. is this normal? There's never any genuine nastiness going on, just power struggles it seems. When he goes to other peoples houses they always say he has been good as gold