Why mars bar hates jeffrey magee?

In the book "Maniac Magee" by Jerry Spinelli, the character Mars Bar Thompson initially dislikes Jeffrey Magee, also known as Maniac, due to his own insecurities and the racial tensions present in their community. Mars Bar represents the local bully, and he feels threatened by Jeffrey's bravery and ability to bridge the divide between different social groups. As the story progresses, Mars Bar's feelings evolve, reflecting themes of growth and understanding. Ultimately, their rivalry serves to highlight the broader issues of acceptance and friendship in the face of prejudice.