"Personally, I think you're both a little lacking in the intelligence department if you think I'm going to come over here and make some kind of ruling on who was right and who was wrong when I didn't see what happened.", Bruin replied simply. "I just came over to make sure that it didn't escalate any further."
Bruin paused for a moment, looked to ensure that nobody was otherwise injured and that no wands were drawn before continuing. "Seeing as nobody's hurt and that the only thing that appears to be wrong is with your mouths, perhaps you could go back to using them for eating so the rest of us can enjoy our breakfast." Bruin didn't really enjoy this aspect of being a Prefect, but realized from personal experience just how quickly petty squabbles could escalate into something more serious, especially when girls from Slytherin were involved.
Bruin wanted to go back to eating, but decided he would wait until the Ravenclaw girl either headed back to her table or left the Great Hall before he would consider the situation over. Perthro might not slouch, but she could still use a little work on her manners, he thought to himself as he stood there waiting to see how the girls might react.