Connell is a popular, athletic high school student living in the small town of Carricklea. Raised entirely by his young single mother, he attempts to blend in with his boisterous peers while hiding his introspective, bookish nature. He cares deeply about social standing, which often puts him at odds with his own instincts and desires.

Marianne is a brilliant, wealthy student who lives in a large house in Carricklea but feels entirely disconnected from her peers. She actively rejects the high school social hierarchy, presenting a prickly exterior to mask the deep insecurities inflicted by her cruel family. Despite her outward confidence, she struggles profoundly with her self-worth and independence.

Lorraine is Connell's mother, a woman who raised him entirely on her own after becoming pregnant as a teenager. She works as a housekeeper for the Sheridan family to make ends meet. She is fiercely independent and deeply empathetic. She holds strong moral convictions that she expects her son to follow.

Denise is Marianne's mother, an exceptionally wealthy widow who maintains a cold distance from her daughter. She is highly concerned with appearances and adheres rigidly to traditional societal expectations. Rather than protecting Marianne, she openly favors her son and turns a blind eye to hostility within the home.

Alan is Marianne's older brother. He struggles to succeed outside the home and overcompensates by acting aggressively within it. With his mother's implicit approval, he constantly targets his sister with intimidation and hostility to assert a sense of superiority.

Rachel is one of the most popular girls at the Carricklea high school. She represents the conventional social path that Connell's friends expect him to take, and she harbors a clear romantic interest in him.

Jamie is a highly affluent student at Trinity College who moves in the same elite circles as Marianne. He masks a deep insecurity with aggressive boasting and boorish behavior, often dominating conversations and demanding submission from those around him.

Helen is a medical student who dates Connell during his time at university. She offers him a sense of straightforward normalcy and social security, contrasting sharply with the complications of his past relationships.

Peggy is a university student who befriends Marianne in Dublin. She is heavily focused on social status and power dynamics, often adopting a superficial approach to relationships and overlooking the toxic behavior of her affluent peers.

Joanna is a grounded university friend of Marianne's. Unlike the rest of the wealthy Trinity circle, she is hardworking and sincere, offering Marianne a reliable and unpretentious connection.

Paula is an economics teacher at the high school in Carricklea. She pays an inappropriate amount of flirtatious attention to her male students, using her position of authority in a predatory manner.

Eric is a member of Connell's high school friend group. He is boisterous and eager to adhere to the loud, aggressive social norms expected of young men in Carricklea.

Niall is a university student from Belfast who rooms with Connell in Dublin. He provides Connell with a comfortable, easygoing friendship in an otherwise alienating academic environment.

Karen is a high school student in Carricklea who breaks away from the mean-spirited norms of her peers. She shows unexpected decency and kindness toward those the group normally shuns.

Lukas is a Swedish photographer Marianne dates while studying abroad. Despite his refined artistic taste, he introduces controlling and damaging dynamics into their relationship.

Rob is a high school student in Carricklea who runs in Connell's social circle. He is deeply consumed by a need for popularity and maintaining outward appearances, which masks severe internal distress.