Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
The Honest Truth
Victor is telling a story that he cannot tell anywhere else—because Mam has made him promise to keep the details of confronting Ara T on the down low—so he exercises full honesty when speaking to the reader in Paperboy. This is his chance to spill the story of his summer in all its juicy detail, so Victor tells it like it is, even refusing to spare himself the awkwardness of dealing with his stutter and how he's made fun of by other kids. Heck, he doesn't even try to hide the fact that he feels shame when he has to talk to other people:
The reason I hate talking to people who don't know me is because when they first see me I look like every other kid. Two eyes. Two arms. Two legs. Crew-cut hair. Nothing special. But when I open my mouth I turn into something else. Most people don't take the time to try to understand what's wrong with me and probably just figure I'm not too right in the head. They try to get rid of me as fast as possible. (1.21)
The tone of Paperboy is brutally honest because Victor wants the reader to understand what he's going through—and in telling his story in such a straightforward, truthful way, he comes across as a super trustworthy narrator. He doesn't hide anything from the reader… or from himself.