Sunday is a twenty-nine-year-old waitress living an isolated life in Los Angeles until a drunk-driving accident prompts her return to West Manor, New York. As the only daughter in a tight-knit Irish Catholic family, she traditionally managed the household's domestic responsibilities and served as her brothers' emotional center. She carries deep guilt over her sudden departure five years ago and harbors a heavy secret regarding her true reasons for leaving. Upon returning home, she cautiously attempts to reintegrate into the family dynamic while facing the unresolved relationships she left behind.

Denny is the oldest Brennan sibling and the ambitious co-owner of the family's pub. He feels a heavy, self-imposed responsibility for his family's success, leading him to take on immense financial stress while attempting to open a second restaurant location in Mamaroneck. His deeply ingrained habit of hiding his problems severely strains his personal life, directly contributing to a recent separation from his wife.

Kale is Denny's childhood best friend and co-owner of Brennan's pub. Having grown up with an absent mother and an older father, he practically integrated into the Brennan family as a seventh member during his youth. He built a stable adult life by marrying Vivienne and having a son, but Sunday's sudden return to West Manor reawakens old feelings and threatens the domestic stability he worked hard to achieve.

Jackie is the third Brennan sibling and a talented artist who works as a bartender at the family pub. He recently finished a probationary period following a drug possession arrest and actively seeks to rebuild a positive life. As the sibling closest in age to Sunday, he shares a special connection with her and serves as the primary advocate for open communication within his highly secretive family.

Mickey is the patriarch of the Brennan family and an immigrant who fled sectarian violence in Belfast to build a prosperous life in America. He worked for years in construction to provide for his family and now takes part-time shifts at the pub. He experiences occasional memory issues and harbors old regrets from his past, fueling his intense desire to keep his reunited family safely together.

Vivienne is Kale's wife and works as an administrative assistant at their son's school. Having grown up in poverty on the outskirts of West Manor, she resents the Brennans' wealth, social standing, and insular family dynamics. She provides a grounded, outside perspective on the family and fiercely guards her marriage against Sunday's sudden reappearance in town.

Billy is a former classmate of Denny who recently returned to New York after living in Katonah and Belfast. He immigrated from Northern Ireland as a child when his father worked for Mickey Brennan. He currently acts as a private investor for the Brennans' new restaurant location, holding significant and dangerous financial leverage over Denny.

Maura is the deceased mother of the Brennan siblings. Raised in a strict Irish Catholic household, she internalized traditional teachings and prioritized maintaining a respectable public image over emotional vulnerability. Her rigid approach to parenting, handling of her cancer diagnosis, and intense fear of scandal left a lasting impact on how her children handle shame and secrecy.

Theresa is Denny's estranged wife. She recently separated from him, taking their young daughter to stay at her sister Angie's house. She is deeply frustrated by Denny's refusal to share his burdens and his tendency to shut her out of his life, demanding a true partnership rather than silent provision.

Shane is the youngest Brennan sibling. He has an intellectual disability and relies on his family for emotional support and daily structure. He works at a local grocery store, loves watching Yankees games, and provides an innocent, grounding presence for his deeply conflicted older siblings.

Clare is Mickey's sister and the aunt of the Brennan siblings. She immigrated to the United States from Northern Ireland alongside Mickey to start a new life and raise her daughter away from the rigid judgment of their traditional community.

Grail is Clare's daughter and a cousin to the Brennan siblings. She works as a local detective, bringing a practical and authoritative energy to family gatherings. She acts as an older sister figure to Sunday, occasionally offering her blunt advice.

Michael is a lawyer and a former classmate of Denny. He handles the legal aspects of Denny's business expansion and offers professional counsel regarding Denny's impending marital issues. He also takes a polite interest in Sunday's writing aspirations.

Molly is Denny and Theresa's four-year-old daughter. Her sudden departure from the Brennan household deeply affects her father, and she experiences anxiety stemming from the unspoken tension in her parents' marriage.

Luke is Kale and Vivienne's young son. He serves as the primary anchor for his parents' marriage, with both Kale and Vivienne fiercely dedicated to providing him with a stable and happy upbringing in West Manor.