Billy Watson, Emmett's precocious eight-year-old brother, is wise beyond his years but also naïve in seeing the best in others. He is curious, enthusiastic, and capable of forming positive relationships with people easily. Billy deeply loves his older brother Emmett and relies on him for protection and guidance, despite the risks of being too trusting with strangers.

Duchess is raised by a con artist father and lacks the essential traits for maintaining positive relationships. Growing up in the theatrical environment, he has a skewed sense of morality shaped by his past hardships. Duchess’s actions are often self-serving, and he struggles with honesty and boundaries, making him an unreliable narrator.

Woolly Martin, older than the other young men in *The Lincoln Highway*, comes from a privileged background but faces developmental and psychological challenges. He finds solace in his family’s history and has a deep bond with his sister, Sarah. Despite his compassionate nature, his limitations often result in him getting into trouble. Woolly seeks to avoid conflict and please others, struggling to find his place in a structured world.