Geeky, orphaned Thomas lives on the Coeur d'Alene reservation in Idaho where he's reluctantly looked after by stoic Victor, whose long-gone father Arnold saved Thomas from the fire that killed his parents. When Victor learns of Arnold's death in Phoenix, Thomas says he'll pay the expenses of the trip if he can accompany Victor. The young men reach an understanding during their travels, while Victor struggles to deal with his complicated feelings about his father and the past.
These films contain examples of:
Abusive Parents: Victor's parents. Arnold is the more pressing case, being willing to strike Victor across the face and even beat his mother right in front of him. His mother isn't innocent either, as it's made pretty clear that her alcoholism was impairing her parenting for most of Victor's early childhood. She does, however, get heaps of credit for finally realizing this trope was at play and then defying it the best that she could.
Actor Allusion: In a flashback, Arnold asks his son Victor who his favorite Native American is. Victor replies "Nobody," as in he has no favorite Native American, which gets his father upset. Gary Farmer played Nobody in Dead Man.
Adaptation: From the short story This Is What It Means To Say Phoenix, Arizona, featured in the short story collection Lone Ranger And Tonto Fistfight In Heaven by Sherman Alexie.
Adaptation Expansion: The movie includes a number of additional scenes and plot points that don't appear in the original story, many of which are adapted from other stories in the collection by Alexie.
The movie also adds the character of Suzy Song, who doesn't appear anywhere in Lone Ranger And Tonto Fistfight In Heaven.
Adorkable: Thomas is this as a kid complete with huge glasses.
Huge Guy, Tiny Girl: Arnold and Suzy. Amplified by the fact the Arnold is quite wide around the waist.
Important Haircut: Victor cuts his hair with a folding knife when faced with the family mementos kept by his runaway father. He had previously told Thomas that long, free-flowing hair is an Indian man's sign of pride.
Jerkass: Victor has shades of this. Though not outright unpleasant he is not above bullying his friends and isn't exactly nice to Thomas. It becomes particularly prominent with his interactions with Suzy.
There is also that bit where he proceeded beat the crap out of poor Thomas when they were kids.
To his credit though, Thomas had just finished asking Victor if the reason his father Arnold had left their family was because he hated Victor.
Victor still has his moments too: When Thomas demonstrates how different substances burn in different colors, Victor asks him what color his parents were when they died.
Mama Bear: Arlene is a strong but nonviolent example of this. After a night of "boozing", she wakes up at the sound of a young Victor breaking beer bottles on the side of their house. The impact of seeing her son in that state prompts her to stop drinking. Being an alcoholic, the fact that she goes cold turkey and evidently STAYS on the wagon not only doubles over as a Crowning Moment of Awesome but proves the lengths she will go to for her son. She is even willing to put up with Arnold's beatings if it means Victor won't have to see her or Arnold drunk ever again.
Took a Level in Kindness: After verbally abusing Thomas for the better part of their journey, when they finally arrive home Victor thanks Thomas and gives him some of Arnold's ashes. To Thomas this is a VERY BIG DEAL.