Fall On Your Knees by Ann-Marie MacDonald is a nuanced and oftentimes deeply tragic rumination on family, and Lily exists as both a symbol of the Piper family's complex history as well as a character who has the chance to uncover the truth and redeem their legacy.
One of the central mysteries of the novel is the identity of Lily's father. Kathleen became pregnant with Lily and Ambrose while living in New York, and after Kathleen dies during childbirth, Lily is raised believing that James and Materia are her parents. It is only at the end of the novel, after Lily herself has travelled to New York and met her mother's lover, Rose, that the truth is exposed: James, who had long been obsessed with his daughter Kathleen, raped her in a fit of jealousy after discovering her relationship with Rose. Lily, then, is the product of both incest and sexual assault.
Yet, for all the trauma of Lily's conception, she eventually becomes a beacon of love and innocence within the Piper family. Mercedes views her as a saintly figure, and Lily is raised believing that her deceased twin, Ambrose, is her guardian angel. Frances's attempted baptism of Lily during her infancy results in her contracting polio, and her survival is treated as a miracle, although she is left disabled by the disease. Even Lily's disability positions her as something of a saintly or martyr-like figure, and her apparently mystical connection to her drowned brother gives her insight beyond her years. Although her family oftentimes continues to suffer around her, Lily retains her gentle innocence and gives her father and sisters a source of much-needed levity and affection.
For much of the novel, the focus is on the shame, dishonesty, and misfortune that have plagued the Piper family. However, the ending shifts focus to notions of redemption. James confesses his sins to Frances, and Lily starts a new life in New York, armed with Kathleen's journals. Mercedes, the final keeper of the family's secrets, sends Frances's long-lost son to meet Lily in New York, and the two finally discover the full truth behind the Piper family tree. With the secrets that have plagued the preceding generations finally out in the open, the novel suggests that perhaps Lily and Anthony can redeem the tarnished Piper legacy and forge a more loving, honest, and innocent future.