Elizabeth Tate Collins, who goes by Tate, is a 23-year-old registered nurse pursuing her master's degree. She relocates from San Diego to San Francisco, planning to focus strictly on her education and career while living with her older brother. Compassionate and driven, her natural inclination to care for others complicates her attempt to avoid messy emotional entanglements.

Miles is a 25-year-old airline pilot who lives across the hall from his friend Corbin. He harbors unresolved pain from his past that makes him fiercely guarded and resistant to emotional vulnerability. Despite his strict personal rules designed to keep people at a distance, he struggles to maintain his detachment when interacting with Tate.

Corbin is Tate's 25-year-old older brother and an airline pilot. He acts as a dutiful host by letting his sister live with him while she settles into the city. He is highly protective of Tate, occasionally stepping into a bossy role to shield her from bad influences.

Cap is the 80-year-old elevator attendant in Corbin's apartment building. He provides comedic relief through his quirky observations but also acts as a wise mentor figure for the residents. He quickly befriends Tate and uses his perceptive nature to offer her grounded perspective.

Rachel is a high school student who relocates from Phoenix, Arizona, and instantly captures young Miles's attention. She is thoughtful and unafraid to bend the rules when necessary. She remains deeply committed to her secret relationship with Miles despite their vastly complicated family dynamics.

Ian is Miles's perceptive best friend who has known him since high school. He attended flight school with both Miles and Corbin, maintaining a close bond with both men. He is highly observant, unhesitatingly honest, and often serves as a necessary voice of reason.

Dillon is a married resident in the same apartment building as Tate, Corbin, and Miles. He acts as an abrasive force against the more respectful characters. His consistent disregard for boundaries highlights the integrity of those around him.

Lisa is Rachel's mother. She begins dating Miles's father, which unexpectedly forces Rachel and Miles into a complicated domestic situation right as they begin falling for each other.

Miles's father is a flawed parent trying to adjust to life after his wife's illness. His new romantic relationship causes friction with his son, complicating their family dynamics just as Miles finishes high school.

Tate and Corbin's mother is a welcoming presence who happily hosts her children for the holidays. She pays close attention to her daughter and is perceptive enough to sense the unspoken tension in the room.

Tate and Corbin's father is a protective parent who enjoys having his family together. He unintentionally interrupts a charged moment between his daughter and her brother's friend during the holiday visit.

Chad is a male nursing student who frequently studies with Tate. His platonic presence in Tate's life unintentionally triggers jealousy and tension from others in her apartment building.

Tarryn is one of Tate's friends and peers in her nursing program. She provides a sense of routine for Tate in San Francisco, helping her focus on her academic goals.