Theodore Finch, an Indiana native, is a brilliant, witty, artistic 17-year-old high school student; he is one of the two teenage narrators of the story. He resides with his mother, a kind-hearted but overwhelmed, depressed, and ineffective single parent; his 18-year-old sister, Kate; and his eight-year-old sister, Decca. His father, a retired hockey player who recently divorced his wife to marry a younger woman, has always been physically and emotionally abusive to Finch.

Finch and the book’s other narrator, Violet Markey, eventually become a couple. Finch assists Violet in overcoming the emotional trauma stemming from the loss of her older sister. Despite heroic efforts to avoid falling “asleep,” he succumbs to depression from untreated bipolar disorder and commits suicide by drowning himself in the Blue Hole, an allegedly bottomless lake. This character functions as a cautionary tale regarding untreated mental illness and the inability of others to recognize signs of teenage suicidality. 

Violet Markey experiences trauma from the death of her older sister, Eleanor, in a car accident. Violet is a bright, skilled writer who has lost interest in many of her former activities and friends. Her devoted and well-meaning parents enrage her by failing to express their grief at Eleanor’s death.