My Sister, That Marquess's Son Is a Spy

Cynthiahas spent years suffering under her abusive father and stepfamily while secretly protecting her younger brother. She is forced to help with her father's illegal activities because her brother is being used as leverage against her. Her life changes when Alan, a handsome marquess's son, appears to court her half-sister. Cynthia initially doesn't realize that Alan is actually a royal spy investigating her family's crimes. Once he uncovers the truth, Cynthia is finally freed from her family's control. Alan, who initially appears cold and calculating, begins protecting and caring for Cynthia, giving her the affection and security she has never experienced.