Conrad is an 18-year-old high school junior who recently spent eight months in a psychiatric facility following a suicide attempt. Once a straight-A student and star swimmer, he now experiences depression and survivor's guilt over the loss of his older brother. He suppresses his emotions to appear normal to the outside world, a strategy that leaves him feeling deeply isolated from his peers and parents.

Cal is a 41-year-old tax attorney, husband, and father. Orphaned at age 11 and raised in an Evangelical home, he places immense value on providing safety, order, and stability for his family. He internalizes his own needs, worrying obsessively about his son's recovery while trying to maintain peace within his household.

Beth is Cal's wife and Conrad's mother, a woman who values order, cleanliness, and the image of a flawless family. She is highly private about her emotional life and channels her sorrow into maintaining an immaculate home and planning trips abroad. She finds it difficult to accept the uncontrollable, messy aspects of trauma and resists discussing past tragedies.

Dr. Berger is a psychiatrist based in Chicago whom Conrad begins seeing after leaving the hospital. He has piercing blue eyes, an unpredictable energy, and a casual style that contrasts sharply with the Jarrett family's rigid perfectionism. He emphasizes feeling true emotions over maintaining strict self-control.

Jordan "Buck" Jarrett is Cal and Beth's eldest son, who passed away in a tragic boating accident over a year prior to the novel's start. Described as carefree, strong, and the ideal child, his memory casts a long shadow over the surviving members of his family, particularly his younger brother who modeled his own life after him.

Lazenby is a high school swimmer and one of Conrad's oldest friends. He was also a good friend of Conrad's late brother. He genuinely cares about Conrad and frequently attempts to bridge the emotional gap that has formed between them, maintaining loyalty even when Conrad pushes him away.

Jeanine is a new student at Conrad's high school with peach-colored hair and a gifted singing voice. She participates in the school choir, which provides her with a space to express her musical talent. She becomes a source of positive connection and normalcy for Conrad as they begin spending time together.

Karen is a young woman who bonded with Conrad during their shared time in the psychiatric hospital. She tries to manage her mental health struggles independently and is hesitant to engage in deep emotional conversations, preferring to maintain a facade of recovery to avoid triggering negative feelings.

Ray is Cal's law partner and friend. He observes Cal's intense worry over Conrad and frequently offers well-meaning, though sometimes unsolicited, advice regarding family dynamics based on his own marital history.

Arnold Bacon was Cal's former mentor, a man who provided the orphaned Cal with guidance and a path toward a legal career. Their relationship fractured entirely when Cal chose to marry Beth against Arnold's advice, leaving a lasting mark on Cal's sense of identity.

Salan is the high school swim coach. He is blunt and lacks empathy regarding Conrad's mental health struggles, frequently badgering him about his decreased athletic performance and medical treatments.

Stillman is a high school swimmer who rides in Lazenby's carpool. He is an arrogant, antagonistic peer who frequently needles Conrad and other students, exhibiting a distinct lack of sensitivity toward Conrad's fragile state.