Boris is Theo’s cosmopolitan best friend in Las Vegas with a distinctive accent, who introduces Theo to a world of illegal substances and becomes a pivotal figure of chaos and support in his life.

Pippa is the artistic younger half-sister of Welty and Theo’s infatuation, serving as a key figure of beauty and fixation for him.

Hobie is the kind and steady part owner of an antiques shop and becomes a replacement parental figure to Theo, providing stability and order after Theo's mother dies.

Larry is Theo’s unpredictable and manipulative alcoholic father whose actions add chaos to Theo’s life, particularly after they reunite in Las Vegas.

Audrey is Theo’s mother, whose vibrant and charismatic presence remains influential throughout the novel despite her early death in a tragic incident.

Andy is Theo’s friend, characterized by his maladjustment, who provides support after Theo’s mother’s death when Theo stays with his family.

Mrs. Barbour is a wealthy and art-collecting socialite who takes Theo in after his mother’s death, offering him a glimpse into a world of beauty and sophistication.

Kitsey is Andy’s sister and Theo’s fiancée, known for her constant cheerfulness and enthusiasm, contrasting with Pippa's intensity.

Xandra is Larry’s girlfriend, notable for her fit appearance and drug use, influencing Theo’s life during his time in Las Vegas.

Welty is Pippa’s much older half-brother and a partner in an antiques shop who gives Theo instructions that significantly impact his journey.