Artie is a 57-year-old high school history teacher in a coastal Massachusetts town. He presents a jovial, warm exterior to his students and colleagues, but privately suffers from deep isolation and loneliness. He often feels like an outsider in his affluent wife's social circle, maintaining a quiet adherence to his working-class roots.

Evie is a pragmatic family therapist who comes from a wealthy, established background. Her emotionally distant demeanor contrasts sharply with her husband's expressiveness, creating a quiet tension in their marriage. She is highly protective of the family structure she has built and prefers to maintain stability over addressing uncomfortable truths.

Rob is Artie and Evie's adult son, working as a software engineer. He is quiet and inwardly focused, carrying heavy guilt from a fatal car accident during his youth. He is currently sorting through a transitional phase in his life, separating from his older wife and attempting to start fresh.

Reginald is Flossie's late husband, a brilliant but arrogant math professor. Though deceased, his cynical philosophies and past actions cast a long shadow over the surviving characters. He famously believed that "each man is an island," reflecting his emotional detachment from those around him.

Francesca is a world-renowned concert pianist and Rob's older wife. Despite their current separation, she remains a deeply empathetic and stabilizing presence in his life. She is highly talented and possesses a maturity that provides Rob with a sense of grounding.

Danny is a high school student in Artie's history class who initially presents himself as an aggressive, typical teenager. Beneath his tough exterior, he struggles with his parents' failing marriage, processing his anger and sadness through misbehavior and acting out at school.

Rhonda is a socially awkward, vulnerable high school student who frequently experiences bouts of sadness. She deals with the social stigma of her mother's mental illness, making her an easy target for bullies, but she maintains an openhearted and kind disposition.

Flossie is an energetic, highly emotional woman and a close confidante to Artie. Her loud personality and willingness to be authentic provide Artie with a rare emotional outlet. Her departure from Massachusetts leaves a significant void in Artie's social life.

Ken is a cheerful, decent man from a working-class South Boston background. After pulling Artie from the water, the two men quickly form a strong bond based on their shared cultural roots, becoming regular fixtures in each other's lives.

Rachel is a younger woman who briefly dates Rob Dam. She is insecure and causes tension within the Dam family due to a habit of impulsively taking small items from their home.

Hoover is the principal at the high school where Artie teaches. He feels the intense pressure of the current political climate, reluctantly asking his staff to alter their lessons to appease angry parents.

Anne is a fellow teacher and friend to Artie. She is observant and tries to maintain a connection with him, though she senses the growing emotional distance as Artie becomes more withdrawn.

Tom is a local plumber and the father of Danny Marino. He is overwhelmed by his own domestic crises, resulting in an emotional breakdown in front of a client.