Macon is a 42-year-old travel writer living in Baltimore who crafts guides for business travelers desperate to avoid discomfort or novelty. Following the sudden death of his twelve-year-old son, Macon retreats into rigid, highly organized routines and systems to manage his daily life. His aversion to change and social interaction isolates him from the outside world, testing his marriage and personal connections.

Muriel is a quirky, talkative dog trainer and veterinary clinic employee who lives in a working-class Baltimore neighborhood. She takes an immediate interest in Macon and his unruly corgi, using her persistent and unapologetic nature to push her way into his life. A single mother who has endured significant hardship, she represents the unpredictable chaos that Macon usually avoids.

Sarah is Macon's wife of twenty years, struggling to process the sudden death of their son. Formerly a social and outgoing woman who enjoyed parties, she finds herself retreating from the world and growing increasingly frustrated with Macon's emotionless, systematic grieving process. She initiates their separation in search of a different way to live with her loss.

Rose is Macon's unmarried sister who serves as the caretaker of the Leary family home. She supports her brothers Charles and Porter by meticulously maintaining the household, alphabetizing groceries, and adhering to strict daily routines. She shares Macon's severe organizational idiosyncrasies and resistance to the outside world.

Julian is Macon's laid-back publisher at the Businessman's Press. Despite living a bachelor lifestyle in a singles apartment complex, his true passion is boating on the Chesapeake Bay. He harbors a deep desire to be part of a close-knit family, making persistent attempts to socialize with Macon and taking a strong interest in Rose.

Charles is one of Macon's brothers who returns to the family home following a divorce. He relies entirely on Rose to manage his daily life and shares his siblings' peculiar habits, including their insular nature and commitment to family rituals.

Porter is Macon's divorced brother who also lives in the Leary family home. He shares custody of his three children and often struggles to figure out how to entertain them during his visitation weekends, defaulting to taking them out to eat.

Alexander is Muriel's young, sickly son who suffers from numerous allergies and health complications. Born prematurely, he is accustomed to a chaotic life and a lack of attention from his extended family, making him surprisingly receptive to Macon's quiet guidance.

Ethan is Macon and Sarah's twelve-year-old son, who was tragically killed at a burger restaurant while sneaking away from summer camp. Though he does not appear in the present narrative, his memory and the trauma of his unexpected death heavily dictate the actions of his parents.

Edward is a corgi originally belonging to Ethan. Following Ethan's death and Sarah's departure, Edward's behavior deteriorates into aggressive anxiety, reflecting the instability of the household. His unruly actions ultimately force Macon to seek outside help.

Garner is a friendly neighbor of Macon and Sarah. He attempts to bridge the gap between Macon and the rest of the community following Ethan's death, though he finds Macon's extreme aloofness frustrating to deal with.

Susan is Porter's fourteen-year-old daughter. During a day trip with Macon, she opens up about her own grief regarding her cousin Ethan, helping Macon realize that he and Sarah are not the only ones mourning the boy.

Mrs. Dugan is Muriel's highly critical mother. She shows noticeable indifference toward her grandson Alexander and frequently disparages Muriel's life choices while clearly favoring her younger daughter.

Claire is Muriel's teenage sister. She initially appears to have a better relationship with her parents than Muriel does, but she soon grows frustrated by their intense scrutiny and suspicious nature regarding her social life.