What’s the deal between Brett and the blonde?

Brett is part of the frats and so is the blonde. But unlike Brett, who is respected by the other members, the blonde was only accepted because of his family and is constantly the target of bullying. At this party, Brett realized that Martin would bully the blonde and took action to prevent that from happening, but the blonde is not grateful because he thinks that Brett is a bully like the other members of the group.