Sadie is a portrait artist who abandoned medical school to pursue a creative career. She lives in a rooftop loft with her dog, Peanut, and relies on selling art online to make ends meet. A sudden brain surgery leaves her with prosopagnosia, which severely affects her ability to recognize faces and paint portraits. She is fiercely independent, often resists help from others, and carries unresolved grief over the death of her mother.

Joe is a resident in Sadie's apartment building. He frequently wears a bowling jacket with his name on it and rides a Vespa. Sadie initially misjudges him based on an overheard phone conversation and assumes he is a dismissive womanizer. However, he gradually reveals a helpful and steady nature. He consistently offers assistance to his fellow tenants.

Sue is Sadie's energetic best friend and initial portrait model. Her parents own the building where Sadie lives. She supports Sadie's art career, though she sometimes struggles to grasp the practical realities of Sadie's face blindness. She is outgoing and often tries to cheer Sadie up through social events.

Parker is Sadie's stepsister. She holds a long-standing grudge against Sadie and frequently uses cruelty and manipulation to undermine her. Parker recently moved into Sadie's apartment building, which brings their historical high school tensions back into Sadie's daily life. She seeks validation from her mother and stepfather while actively working to isolate Sadie.

Sadie's father is a renowned heart surgeon. He maintains a strained, emotionally distant relationship with his daughter and primarily communicates with her about medical or practical matters. He insists she undergo immediate brain surgery after discovering her cavernoma. He avoids discussing the family's shared grief over his first wife's death.

Dr. Nicole is the neuropsychologist assigned to Sadie's case. She officially diagnoses Sadie with prosopagnosia and provides regular therapy sessions. She balances professional objectivity with empathetic encouragement. She pushes Sadie to be honest with others about her condition instead of hiding her struggles.

Dr. Addison is a smartly dressed veterinarian who treats Sadie's dog, Peanut. Sadie develops an immediate, idealized crush on him based on his posture and style, and views him as a potential romantic partner. He is attentive to his animal patients and shows sympathy for Sadie's distress over her pet's health.

Lucinda is Sadie's stepmother and Parker's biological mother. She often tries to mediate family situations but typically sides with her daughter. While Sadie resents her presence, Lucinda occasionally makes practical attempts to assist Sadie, such as offering financial help during her medical crisis.

Peanut is Sadie's dog and constant companion. Gifted to Sadie for her fourteenth birthday, he represents her strongest connection to her late mother. His sudden illness requires intensive veterinary care, which adds to Sadie's daily stress during her recovery.

Mr. Kim is Sue's father and the owner of the apartment building where Sadie lives. He allows Sadie to reside in the rooftop loft rent-free so she can pursue her art career.

Witt is Sue's boyfriend. He and Sue frequently travel together. Their spontaneous relationship decisions directly impact Sue's availability to sit as Sadie's portrait model.

Dr. Estrera is the brain surgeon who treats Sadie. He performs the operation to remove her leaking cavernoma and monitors her subsequent brain swelling and recovery.

Augusta is a former high school classmate of Sadie and Parker. Her past experiences with Parker's severe bullying resulted in significant fallout that altered the course of Sadie's adolescence.

Ezra is Sadie's ex-boyfriend. Their recent breakup leaves Sadie cynical about romance and uninterested in pursuing new relationships.

Nora is Sadie's deceased mother. She was an artist who died suddenly when Sadie was fourteen. Her memory continues to deeply influence Sadie's artistic aspirations and personal choices.

Skylar is Joe's ex-wife. Her past infidelity caused their divorce and led Joe to sell most of his belongings.

Marie is an evolutionary biologist and herpetologist who lives in the building. Sadie initially assumes she is one of Joe's romantic conquests and nicknames her "Busty McGee."