A high school teacher admired by Leonard for his respectful and attentive approach, who teaches about the Holocaust and offers support to Leonard during difficult times.

A once-close childhood friend of Leonard who became a bully; he is a significant part of Leonard’s struggles at school.

Leonard’s mother, a former model, now a fashion designer, who spends most of her time in New York and is generally inattentive to Leonard.

An elderly neighbor who enjoys watching Humphrey Bogart films with Leonard, providing a fatherly presence in Leonard's life.

Leonard's father, a former minor rock star known as Jack Walker, who left the country due to legal issues and has a complicated relationship with Leonard.

A devout Christian who Leonard meets at a train station, known for her Bible-centric education and attempts to share her faith with others.

An Iranian American classmate of Leonard’s, a talented violinist who initially keeps to himself but later speaks out regarding Leonard's behavior.