Vincent is a high school valedictorian who takes a summer construction job in 1979 to save money for community college, having forgone his admission to Stanford due to financial constraints. Coming from a large, working-class family, he seeks to prove his capability and maturity among the older men on the job site. As an adult decades later, he works as a lawyer to provide stability for his family, balancing his professional routine with his lingering teenage dream of becoming a writer.

William is an eighteen-year-old high school graduate who volunteers for the Marines to serve in the Vietnam War, assuming he will be drafted regardless. Scoring highly on his aptitude tests, he chooses to be a combat photographer, though he quickly learns this assignment still requires standard infantry violence. By 1979, he is a thirty-year-old construction worker who struggles with undiagnosed post-traumatic stress disorder, masking his wartime memories with heavy alcohol and drug use.

Beau is Vincent and Elizabeth's teenage son, growing up with the financial security and safety his father worked to provide. He plays on his high school football team and wrestles with the desire to assert his independence while remaining heavily reliant on his peer group. His experiences closely mirror his father's youth, presenting Vincent with the challenge of guiding him through sudden, difficult transitions.

Todd manages the construction crew where Vincent and William work during the summer of 1979. As a Vietnam War veteran himself, he maintains a gruff, domineering exterior characterized by a pronounced limp. He expects rigorous effort from his crew and holds the inexperienced Vincent to a strict, physically demanding standard.

Corporal Victor Cruz is an experienced soldier stationed in Vietnam who takes William under his wing. He teaches incoming replacements the unwritten rules of survival, primarily focusing on emotional detachment by forbidding talk about home or how much time a soldier has left on their tour. He hails from Spanish Harlem and functions as a pragmatic guide in a chaotic environment.

Elizabeth is Vincent's wife and the mother of Beau and Mary Beth. She provides a stable presence in the Bianco household and actively participates in her children's athletic pursuits. She notices the emotional weight that William's mysterious package places on her husband.

Chris is Beau's best friend and a star athlete on the high school football team. He faces immense pressure from his father to secure a sports scholarship to Stanford University, as his family lacks the financial resources to pay the tuition outright.

Mary Beth is the younger sister of Beau and a freshman in high school. She plays basketball and actively supports her older brother by attending his football games, experiencing frustration when he fails to reciprocate that support.

Kenny is a young American soldier stationed in Vietnam. As an experienced hunter, he possesses sharp instincts and reacts quickly when their base comes under fire from North Vietnamese soldiers.

Nicknamed Mif, Lenny is one of Vincent's close high school friends. He frequently acts as the driver during their summer outings, participating in the group's reckless partying before leaving for college to pledge a fraternity.

Amy is a young woman visiting her cousin in California from New York. She meets Vincent while he works on the construction site and introduces him to adult experiences, representing his transition away from adolescence.

Mike is Bethany's boyfriend who helps Vincent secure a position at Todd's construction company. He works alongside Vincent and William early in the summer before departing for a different job.

Bethany is one of Vincent's siblings in his large, working-class family. She inadvertently acts as the bridge for Vincent's summer employment through her relationship with Mike.

Donny is part of Vincent's teenage friend group. His insistence on driving his car despite being heavily intoxicated forces Vincent into a dangerous situation that tests Vincent's shifting perspective on mortality.

EZ is a young soldier serving in William's platoon in Vietnam. His proximity to William on the battlefield forces William to confront the arbitrary and random nature of combat survival.