Cain's ten-year-old half-sister. Following her mother's suicide to shield her from an obsessive suitor, Mary survives on the streets of London as a fortune teller. Cain assumes she is his half-sister and takes her in. Bold and spirited, she frequently grows irritated by Cain's romantic entanglements. Though she dislikes how Cain protects her, she tolerates it, sensing it alleviates his pain. Oscar Gabriel, one of Cain's friends, declares himself her fiancé in an attempt to regain his father's attention.
As the story unfolds, he puts his life on the line to safeguard her, leading her to recognize his genuine affection for her. In the epilogue, they are married, and she is expecting their child. Despite the fact that she is not actually related to Cain, he loves her unconditionally.
