Multiple characters could be classified as the most violent character in the story, so the answer is definitely subjective and best left to individual readers. One character that should definitely be considered for the most violent character of the book is Danny's friend Uno. Uno is a big, tough guy. He is not afraid to use his physicality to intimidate others, and readers see this early in the book when Danny out performs Uno at the home run derby competition. Uno takes it upon himself to beat up the half white half Mexican Danny Lopez.

This is not the only time that Uno gets in a fight either; however, it is the only time that Uno physically fights Danny. The two become the closest of friends over the course of the summer, and it is Uno that steps up to fight anybody and everybody that tries to mess with Danny. The two characters have a hustle that involves Danny's pitching, and some of the hustled batters are so enraged at losing their money that they attack Uno and Danny.

The other character that a reader could probably defend for this answer is Danny's Uncle Ray. When Ray finds out that somebody punched Danny, Ray makes all kinds of violent threats about what he is going to do to the guy that hurt Danny. It is a super intense moment in the book, and readers are confident that Ray can absolutely use large amounts of violence and probably has in the past. Danny stays quiet, and that earns Danny a lot of respect from a lot of people in the neighborhood.