Fix is a dedicated police officer living in Southern California. He is a protective family man who values order and suspects anything that threatens the balance of his home. Deeply loyal to his police partner Lomer, Fix relies on rules, justice, and community routines to make sense of the world.

Beverly is Fix's wife and the mother of Frances and Caroline. She is characterized largely by her physical appearance and the immediate effect she has on guests like Bert Cousins at family gatherings. Beneath her polished exterior, she easily becomes overwhelmed by the demands of motherhood and domestic responsibility.

Frances (often called Franny) is the youngest daughter of the Keating family. Growing up in a blended family, she is an avid reader who seeks to understand the complex histories of the people around her. She drops out of law school and works as a cocktail waitress in Chicago during her twenties. She often adopts an accommodating role in her relationships but possesses a deep empathy for her siblings.

Bert is a district attorney in Southern California who feels suffocated by his busy home life with his pregnant wife and three young children. Arrogant and seeking an escape, he drinks heavily at the party. His impulsive kiss with Beverly Keating sets off a chain of events that permanently alters both families.

Teresa is Bert's hardworking wife. Initially overwhelmed by her busy household and fourth pregnancy, she is forced to become fiercely self-reliant. She takes night classes to become a paralegal and works tirelessly to support her four children as a single mother, demonstrating an unyielding determination to keep her family afloat.

Caroline is the assertive eldest daughter of Fix and Beverly. She is determined, highly intelligent, and deeply loyal to her father, sharing his interest in the law. Taking charge naturally, she often acts as the leader among the step-siblings during their chaotic summer vacations.

Cal is the eldest child of Bert and Teresa Cousins. Burdened with responsibility at a young age, he harbors deep resentment toward his father for abandoning their daily household. As a teenager, he is angry and rebellious, frequently taking out his frustrations on his younger siblings while acting as the leader during the children's unsupervised summer vacations.

Jeanette is one of the middle Cousins children. Exceptionally quiet and unobtrusive, she often goes unnoticed by the adults around her. Instead of causing trouble, she is highly observant, quietly carrying the burdens of the group and keeping track of the shared items the children need during their outdoor adventures.

Albie is the youngest of the Cousins children. Often viewed as a burden by both the distracted adults and his older siblings, he is repeatedly excluded from the group's activities. This early isolation fuels a rebellious adolescence, as he joins a group of neighborhood boys who ride bikes and set fires to get attention.

Holly is a daughter of Bert and Teresa Cousins. Like her siblings, she experiences the lack of adult supervision during her childhood summers in Virginia. She carries an underlying anxiety that eventually leads her to explore meditation and seek spiritual grounding at a Zen center in Switzerland.

Leon, who goes by Leo, is a famous, much older author who meets Frances while teaching in Iowa City. He is captivated by her attention and eagerly consumes the stories she shares about her childhood. He uses these family histories as material for a bestselling novel, creating tension between art and privacy.

Lomer is Fix Keating's former police partner and close friend. They spent long hours together working the night shift in Los Angeles, sharing jokes and camaraderie. His memory stays with Fix, serving as a reminder of life's sudden dangers and the inability to protect everyone.

Father Joe Mike is a priest who attends Frances's christening party. Caught up in the lively, intoxicated atmosphere of the gathering, he mentally prepares his Sunday homily by comparing the miraculous flow of shared alcohol and juice to biblical miracles.