Rowdy is Arnold's best friend, arch nemesis, and everything in between. As his name indicates, he's a pretty tough guy.
Rowdy sticks up for Arnold, but he also pushes Arnold around from time to time. Remember the powwow in Chapter 3? Or the confrontation on the playground in Chapter 7? What is the history of violence in Rowdy's own family?
Rowdy becomes Arnold's worst enemy, which we see during the basketball games where the two face off in Chapters 20 and 25. What does it mean for Arnold to defeat Rowdy?
How would you characterize the relationship between Rowdy and Junior at the end of the novel? Can the two ever really be best friends again? Are they part-time friends? Or real friends?