A is a sixteen-year-old who wakes up in a different body every morning. Lacking a permanent family, physical form, or possessions, A relies on a personal email account and reading to maintain a sense of continuity. Accustomed to observing life from the outside, A generally follows strict personal rules to avoid interfering in the lives of the host bodies. This detached existence shifts dramatically upon meeting Rhiannon, prompting a strong desire for genuine connection and a lasting relationship.

Rhiannon is a high school student trapped in an unfulfilling relationship with her boyfriend, Justin. She initially appears diminished and cautious, accustomed to his dismissive behavior. When A treats her with genuine care during a spontaneous trip to the ocean, she reveals a deeply thoughtful and hopeful personality. As she learns the truth about A's existence, she struggles to reconcile her emotional connection with the practical impossibilities of dating someone who changes physical forms daily.

Nathan is a structured, rule-following teenager whose life is upended when A inhabits his body to attend a party. Left with fragmented memories of the night, Nathan deduces that he was possessed and aggressively seeks answers. He utilizes the media and religious figures to make sense of his experience, eventually tracking down A through an uncleared web browser history.

Reverend Poole is an ominous figure who provides counsel to Nathan following the possession incident. He runs a website dedicated to stories of possession and inserts himself into Nathan's search for answers. He displays an intense interest in A's abilities, introducing dangerous new possibilities regarding how possessions function.

Justin is Rhiannon's boyfriend, characterized by a careless demeanor and disregard for those around him. He takes Rhiannon for granted and frequently dismisses her feelings. His narrow worldview and self-centered behavior stand in direct contrast to the attentive care A shows Rhiannon, making him a central obstacle in A's pursuit of a meaningful connection.

Alexander is a kind, artistic teenager with a deep appreciation for culture and creativity. He maintains close, loving relationships with his parents and friends, participating actively in local bands. When A inhabits his body, A immediately recognizes Alexander as someone who shares a similar worldview and capacity for genuine care.

Kelsea is a severely depressed teenager whose mental health struggles go largely unnoticed by her father and peers. During A's day in her body, A discovers her journal and the dangerous depth of her pain. Her situation forces A to make a rare decision to break personal rules and intervene to secure her safety.

Ashley is a beautiful teenager whose appearance constantly draws intense attention from everyone around her. A uses her body to test Justin's loyalty to Rhiannon, experiencing firsthand how people objectify her and project their own assumptions onto her physical form.

Vic is a transgender boy with supportive parents and a strong circle of friends. A feels a powerful sense of identification with Vic, appreciating how he lives authentically despite feeling born into the wrong body. Vic's relationship models the type of complete understanding A desires.

Dana is a troubled teenager dealing with immense guilt and grief following a drunk driving accident that killed her brother, Anthony. A struggles to navigate Dana's suppressed memories and the strict supervision of her devastated parents, experiencing the crushing weight of her trauma.

Zara is a teenager in a secure, loving relationship with her girlfriend, Amelia. A finds comfort in Zara's supportive environment and social circle but also experiences deep sorrow, realizing the impossibility of replicating such an openly acknowledged relationship with Rhiannon.

Michael is a teenager whose family is scheduled to travel to Hawaii for his sister's wedding. Desperate to remain on the mainland near Rhiannon, A hijacks Michael's life by running away, leading to an exhausting bus ride and a physical altercation with Justin.