Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Humorous, Hyperbolic, Hopeful
The First H: Humorous
Arnold is a funny, funny guy and cracks jokes—or draws hilarious pictures—even at his darkest moments. Sherman Alexie has said that "being funny breaks down barriers between people. I can get up in front of any crowd, and if I make them laugh first, I can say almost anything to them" ( "A World of Story-Smoke: An Interview with Sherman Alexie").
We think this most definitely applies to Arnold:
I realized that, sure, I was a Spokane Indian. I belonged to that tribe. But I also belonged to the tribe of American immigrants. And to the tribe of basketball players. And to the tribe of bookworms.
And to the tribe of cartoonists.
And to the tribe of chronic masturbators.
[...]
And the tribe of tortilla chips-and-salsa lovers.
[...]
It was a huge realization.
And that's when I knew that I was going to be okay. (29.31-29.43)
The Second H: Hyperbolic
Arnold is a teenage boy who is just packed full of words and images and ideas and thoughts and feelings. As we see from the novel's first few paragraphs Arnold has about a million different metaphors for every situation:
I was actually born with too much cerebral spinal fluid inside my skull. But cerebral spinal fluid is just the doctors' fancy way of saying brain grease. And brain grease works inside the lobes like car grease works inside an engine. It keeps things running smooth and fast. But weird me, I was born with too much grease inside my skull, and it got all thick and muddy and disgusting, and it only mucked up the works. My thinking and breathing and living engine slowed down and flooded.
My brain was drowning in grease.
But that makes the whole thing sound weirdo and funny, like my brain was a giant French fry, so it seems more serious and poetic and accurate to say, "I was born with water on the brain." (1.1-1.3)
As a character, he's what we might call hyperbolic (or exaggerated). Is this a bad thing? No way. A lover of words, Arnold likes big gutsy images and huge exuberant ideas. Sure he's a little over the top—but that's why we love him. Arnold, much like his writing, is filled to the brim with life.
The Third H: Hopeful
Here's the thing about Arnold— even though he goes through a massive amount of heartache in his life, his writing is almost always hopeful. He's always filled with joy, he always is excited to be alive. In order to cope with all of the death in his life, Arnold makes lists of his favorite foods, books, bands, and basketball players.
Arnold's hope—and his realization that "[he is] going to be okay" (29.43) gives him buoyancy—and is what ultimately leads him to fight for his dreams by leaving the reservation.