What is the main conflict in Luna: A Novel by Julie Anne Peters?

"Luna" by Julie Anne Peters is a highly acclaimed novel about a transsexual teenager, his decision to transition, and the effects of this on his younger sister and sole confidante. When Liam confides that he wants to transition and become Luna all of the time, Regan struggles to keep his secret and help him become comfortable dressing in public, even as it negatively affects her own life and relationships. "Luna" is a touching and realistic portrayal of the challenges, triumphs and heartbreaks a young man must face in order to correct his destiny and become the girl he was born to be.