Sonny is an introspective, quiet high school senior and football lineman living in a rooming house apart from his father. Deeply lonely and observant, he feels alienated in the dying oil town of Thalia. He drives a butane truck for work and relies heavily on his relationships, particularly with his best friend Duane and his mentor Sam the Lion, to make sense of his life. His passive nature makes him a keen observer of the community's quiet desperation.

Duane is a star fullback for Thalia High School and works grueling overnight shifts as a roughneck on a drilling crew. As Sonny's best friend, he represents a more conventional, action-oriented model of masculinity. His life revolves around football, earning money, and maintaining his social status through his relationship with the wealthiest girl in town.

Jacy is the beautiful daughter of one of Thalia's wealthiest families. Bored by the provincial limits of her hometown, she views romance and social interactions as tools for entertainment. She is highly aware of the power her beauty and wealth afford her, often manipulating those around her to secure her social status and avoid the stifling monotony of small-town life.

Sam is an aging former cowboy and rancher who owns several local businesses, including the pool hall and the picture show. He serves as a moral anchor and paternal figure for the town's youth, offering quiet dignity and a living connection to the vanishing frontier past. Despite carrying the grief of losing three sons, he provides stability in a decaying community.

Ruth is the neglected wife of the high school football coach. Trapped in an affectionless marriage for two decades, she exists in a state of quiet despair and isolation. Her life consists of silent endurance in a conservative town until an unexpected car ride allows her to reveal her deep unhappiness and seek human connection.

Lois is Jacy's sharp-tongued, hard-drinking mother who married into Thalia's newly rich oil class. Thoroughly disillusioned with her life and the town's superficial social machinations, she uses acerbic wit and reckless behavior to combat her profound boredom. She offers her daughter shockingly pragmatic, cynical advice about money and men.

Herman Popper is the crude, bullying high school football coach. Publicly revered by some as a rugged model of traditional masculinity, he is privately a neglectful, callous husband and an arbitrary disciplinarian. He masks his own insecurities and repressed desires behind sudden fits of rage and a rigid enforcement of the town's conservative ideals.

Abilene is a sharp-dressed, highly competent oil driller and the undisputed best pool player in the county. Emotionally detached and purely transactional in his interactions, he represents a modern, unheroic form of success in the oil-boom economy. He operates with a cold professionalism that contrasts with the aimless anxiety of the town's younger men.

Billy is a nonverbal young man with an intellectual disability who lives under the care of Sam the Lion. His days are spent constantly sweeping the floors of local businesses and even the town streets. Gentle and defenseless, his repetitive sweeping serves as a constant, innocent attempt to impose order on a dust-blown, declining town.

Genevieve is the kind, observant night waitress at the local café. Burdened by extensive medical debts following her husband's oil rig accident, she works long hours but remains a compassionate presence for the town's youth. She once shared a close friendship with the Farrow family before their oil wealth created a permanent class divide.

Joe Bob is the local preacher's son and a student at Thalia High School. Raised under strict religious doctrines, he is heavily burdened by his father's punitive teachings regarding morality and purity. His suppressed anxieties and internal guilt make him a frequent target for bullying and eventually lead him to make highly destructive choices.

Lester is a wealthy teenager from the neighboring city of Wichita Falls. He uses his family's money to buy status and proximity to Thalia's social scene, willingly losing cash at the pool hall to gain local prestige. His affluence makes him a convenient option for girls looking to experience a faster, richer lifestyle.

Charlene is a high school student whose worldview and approach to romance are heavily shaped by movie magazines. She carefully performs the role of a virtuous girlfriend, strictly enforcing physical boundaries during dates at the local lake to maintain her reputation in the conservative community.

Frank is Sonny's father and a former high school principal. Physically and emotionally devastated by a past car accident that killed his wife and left him with chronic pain, he struggles with prescription drug addiction. His diminished state forces Sonny to live independently at a local rooming house to avoid being a burden.

Gene is Jacy's father and Lois's husband. Though he struck oil and became part of Thalia's wealthy class, rumors circulate about the actual liquidity of his fortune. He is a generally weak but status-conscious man who attempts to protect his family's reputation from unsuitable suitors.

Mr. Cecil is the kind and effective English teacher at Thalia High School. His classroom provides one of the few positive educational environments for students like Sonny. However, his gentle demeanor and willingness to help students outside of class make him a target for the town's vicious prejudices.

Bobby is a wealthy, sophisticated young man from Wichita Falls. Moving in a fast-paced country club social circle, he represents the glamorous, affluent world that teenagers in Thalia aspire to join. He treats relationships with casual indifference and operates by a completely different set of rules than the small-town boys.

Brother Blanton is the stern local preacher who leads town-wide religious revivals. He enforces an uncompromising and punitive version of conservative Christian morality, leveraging public shame and fear to maintain spiritual authority over his congregation and his own family.