Father...?(Ciel X Reader)

(Y/N) is a normal girl. Or at least she seems to be. Her mother died when she and her brother were born and she's never met her real father. She lived with her step father. Her not-so-look-a-like twin brother was kidnapped when they were born. Her step father and her always looked for him but had no luck. Finally, one day, when almost all hope had left them, he returned. One year after his return, his father died. (Y/N) comforted her half-brother and they grew closer. He became over protective of her, saying she was all he had left. She cared for him just as much, if not more. When her step father died, he told her and her half-brother that (Y/N)'s father was someone else that was out there. After he died, the two siblings were determined to find out who her real father is. One day, they attend one of the Queen's balls and they meet Ciel Phantomhive. He's the person whom (Y/N)'s brother envies most. He also has a fiancé. (Y/N) begins to fall for him and feels bad about it...