Paul is a middle-school-aged kid who has a big, bad, mean brother. It's bad enough that he has difficulty seeing and he's in middle-school, but his brother seems to get all the praise and glory at home since he's the athlete in the home. The story is written from Paul's perspective, which gives him the status of greater importance just like a protagonist would in any story. Paul must defeat social and physical obstacles in order to find his niche in his middle-school life. It is through his eyes that the reader gains the greatest knowledge about the setting, plot, conflict, and resolution.
A protagonist is teh hero of a story, or the main character. In Tangerine, the story centers around Paul and his experiences as a transfer student. Paul is an outcast because he is blind, and because he is not a football star like his brother.