You're discouraged from being violent towards others.
Joey gets upset at something rude Tristian said to him.
Joey wants revenge on Tristian.
Joey reports Tristian to the teachers in charge at the moment.
Joey decks Tristian with one punch to the arm in response.
Tristian gets in trouble for being rude to Joey in the first place.
Joey complains that he got in trouble when Tristian was bad first.