Layla is a physician who travels to Paris for the destination wedding of her former sister-in-law. Divorced from Jamie for two years, she attends the wedding out of obligation to his family and intends to maintain a polite facade. The trip causes her significant anxiety, as she must return to the city where she honeymooned and face a family she has largely avoided. She struggles with a pattern of prioritizing the comfort of others over her own emotional needs.

Griffin is Michael's best man and a wealthy inventor who designs building materials. He lives with extensive burn scars, chronic neuropathic pain, and contractures that limit his mobility. To manage his condition, he maintains a reclusive lifestyle in upstate New York and heavily dreads the travel required for the wedding. His blunt honesty and isolated habits stand in direct contrast to Layla's accommodating nature.

Emily is the earnest bride-to-be whose destination wedding brings the characters to Paris. She maintains a deep sisterly bond with Layla and insists on her presence despite the awkwardness of the divorce. Overwhelmed by the pressure of her upcoming marriage and her fiancé's impending move to Germany, she leans heavily on Layla for emotional support as she begins to experience severe doubts.

Michael is the groom preparing to marry Emily. He shares a close, codependent bond with his best friend Griffin, a relationship forged in the aftermath of a shared trauma. Desperate for a fresh start with his future wife, he avoids addressing his parents' open hostility toward Griffin and keeps painful elements of his past hidden to maintain harmony.

Jamie is Layla's ex-husband and Emily's brother. He maintains a polite exterior and insists on treating Layla as family, a behavior that forces her to hide her true feelings. His presence at the wedding events alongside his new girlfriend creates significant tension as he struggles to accept the boundaries of his dissolved marriage.

Rosie is Emily's bold and expressive maid of honor. She serves as a fiercely loyal friend who provides unfiltered commentary on the tense atmosphere of the wedding week, frequently cutting through the pretense of the other guests.

Samantha is Jamie's new girlfriend who accompanies him to the destination wedding in Paris. She frequently experiences sudden illness during the wedding events, inadvertently contributing to the escalating chaos and tension among the guests.

Robert is Jamie and Emily's father. He loves his family but exerts subtle pressure on everyone to conform to an idealized family narrative, openly insisting during a toast that Layla remains part of their family despite her divorce from his son.

Manon is the mother of Jamie and Emily. She contributes to the stressful environment by making intrusive suggestions designed to accommodate her son at the expense of others, heavily investing in the family's romanticized connection to Paris.

Fitz is Michael's rigid and judgmental father. He harbors unresolved hostility toward Griffin due to a past tragedy, frequently criticizing his son's best friend and creating a palpable chill within the wedding party.

Paula is Michael's mother. She acts as a passive figure who deflects her husband's harshness rather than confronting it, often blaming Griffin for her son's bad moods in order to smooth over family tension.

Sara Beth is a figure from Michael and Griffin's past. Her tragic death in a house fire years ago left profound emotional and physical scars on the survivors, and the unspoken grief surrounding her continues to haunt the families involved.

Cara is a fellow medical professional and Layla's close friend back in Boston. She provides Layla with support and a sense of distance from the intense dynamics of the Paris wedding.

Willa is a fifteen-year-old passenger who faints on the flight to Paris, prompting Layla to step in and offer medical assistance.

Céline is Emily's aunt, a member of the extended MacKenzie family who attends the wedding events and casually discusses the family's shared history.