Who stopped mars bar from fighting maniac Magee?

In the novel "Maniac Magee" by Jerry Spinelli, it is Amanda Beale who intervenes to stop Mars Bar Thompson from fighting Maniac. Amanda, a strong-willed character, recognizes the potential for violence and steps in to prevent the confrontation. Her actions showcase her bravery and commitment to standing up for what is right, ultimately helping to diffuse the tense situation.