Charlie’s teacher and friend at the Beekman College Center, who recognizes his potential and supports him throughout the story.

Charlie's coworkers who serve as a source of familiarity, some of whom bully him, impacting his perception of friendship.

An artist and free spirit who enters Charlie's life later, providing him with a contrasting lifestyle and influencing his understanding of relationships.

Charlie's father, who appears in both Charlie’s childhood memories and briefly as an adult, representing a complex family history.

Charlie’s mother, remembered by him for her harsh treatment and sentimentalized through contrasting memories.

Charlie's sister, seen as a child in his memories and reconciled with as an adult, impacting his family relations.

A graduate student at the Beekman lab who conducts tests with Charlie and later becomes a voice of reason and empathy.

A lead researcher focused on the experiment’s success, whose relationship with Charlie is more clinical than personal.

A researcher and therapist involved in Charlie’s procedure, demonstrating more concern for Charlie’s emotional development.