Josie is a kind, mature, and insightful girl who suffers from an illness that limits her activities. She has a close bond with Klara, who is dedicated to her well-being, and she is loved by her family and friends, including her best friend, Rick.

Chrissy is Josie’s mother, characterized by her complex and contradictory nature. She is devoted to Josie but struggles with guilt and regret over past choices related to her daughter's health. Despite her flaws, she loves Josie deeply and plays a significant role in Josie's life and Klara’s narrative.

Rick, Josie's best friend, lives nearby and has known her since childhood. Unlike Josie, he was not "lifted," and he worries about the impact of genetic editing. He is caring, intelligent, and supportive, despite his initial skepticism towards Klara.

Helen is Rick's mother, an Englishwoman with a theater background. She is determined and strategic in her efforts to secure a better future for Rick, showcasing her love and ambition for her son.

Paul, Josie's father, is a talented engineer who lost his job and now resides within a community of displaced professionals. He is dedicated to his daughter Josie, going to lengths to support and protect her.

Mr. Capaldi is the antagonist of *Klara and the Sun*, representing the cold, scientific mindset that embraces genetic editing and other controversial technological advancements. He attempts to persuade others of the harmlessness of his projects while embodying a lack of humanity and faith.