Jimmy is an 11-year-old boy living on the Rosebud Sioux Indian Reservation in South Dakota. Although he is three-quarters Lakota, he has blue eyes, light skin, and light-brown hair, making him look physically different from his peers. He prefers the outdoors and enjoys learning traditional skills from his grandfather. He struggles with his dual heritage and seeks the confidence to face the boys who torment him at school.

Nyles is Jimmy's grandfather, living on a small horse ranch where he passes down Lakota traditions. He serves as a mentor to Jimmy, organizing a cross-country trip to teach the boy about their shared cultural heritage. As a Vietnam War veteran, he maintains a balanced and empathetic view of historical conflicts, emphasizing respect for all individuals involved in battle.

Crazy Horse is a legendary Lakota war leader from the 19th century who features heavily in the oral histories passed down by Nyles. As a boy known as Light Hair, he looks physically similar to Jimmy McClean. He serves as an inspiration for the Lakota people through his bravery and deep sense of responsibility toward his community during the American Frontier Wars.

Corky is a white student at Jimmy's school who frequently bullies him. Larger than Jimmy, Corky bonds with another classmate over their shared enjoyment of tormenting the protagonist, specifically mocking him for not looking sufficiently white despite his European last name.

Jesse is a 12-year-old Lakota boy at Cold River Public School. Despite sharing Jimmy's Lakota heritage, Jesse targets Jimmy for his light hair and blue eyes, claiming he is not a true Lakota. He teams up with Corky Brin to intimidate Jimmy on a regular basis.

Yellow Woman is a Lakota survivor of a violent military raid that destroys her village. She suffers immense personal tragedy during the attack. Her rescue and subsequent journey with Light Hair illustrate the deep community bonds of the Lakota people.

Lone Bear is Crazy Horse's best friend and a dedicated Lakota warrior. He participates directly in the resistance against the encroaching white soldiers, representing the strong camaraderie among the Lakota fighters.

Sitting Bull is a prominent Lakota leader who coordinates huge gatherings of Indigenous tribes to resist territorial expansion. He works as a high-level strategist alongside other warriors to organize defenses.

Conquering Bear is the headman of a Lakota village. He attempts to manage disputes with white settlers through diplomacy and fair trade, though his efforts frequently meet with hostility from the authorities.

White Hat Clark is a white soldier known by the Lakota as a "Long Knife" who operates out of Fort Robinson. He represents the military authority of the United States government during the conflicts on the Great Plains.