Lydia Lee is the main character of Everything I Never Told You, and the mystery of her death drives the novel’s narrative. Lydia’s character is initially enigmatic, because she is primarily revealed through her family’s grief, anxiety, and memories. There are few clues about what, besides her surprising blue eyes, is unique to Lydia. She never wrote a word in any of the diaries her mother, Marilyn, had given her across the years. While her parents believe she is a popular and gifted student, focused on a future career in medicine, this turns out to be false. Her brother, Nathan, thinks Lydia is the latest “victim” of a neighbor, Jack Wolff, who has a reputation for sexual promiscuity. This also proves untrue. As the novel unfolds, it becomes clear that she is deeply unpopular, initially by choice, and is struggling in school. Lydia has started spending time with Jack, but he is not interested in her sexually. In many ways, Lydia’s character is a mystery even to herself because she decided in childhood to say yes to everything Marilyn wanted for her.  

Being the focus of her parents’ attention suffocates Lydia, who suppresses her own identity to fulfill those her parents project upon her. She constructs elaborate pretenses to convince her father, James, that she has a group of friends, and she assents to each of Marilyn’s rigorous academic plans. Lydia increasingly resents these demands and expectations. At the same time, however, she cannot tolerate those moments when Nathan upstages her, as when he is accepted to Harvard. She steals the information the university sends and announces that she is failing physics as the family celebrates his achievements. Lydia might want to be free to make choices for herself, but her character has still been shaped by her parents’ unwelcome attention, making her selfish and even cruel. Before she dies, however, Lydia realizes that she must begin to make her own choices, even if that means letting her parents down.