The Queen's Cobra. (Ciel x Reader)

Y/n is the queen's best assassin more commonly know Queens Cobra or the Cobra. She can be in any crowd and you wouldn't even know it until it's to late. No one knows her real identity expect for select Nobles. She knows nothing of her past except for her crest of which she where's around her neck. One day she is sent to work with Ciel to find out who is behind the murder of 16 women. Along the way she learns about her past. She soon starts to feel a strange emotion towards the young master she once despised could it be love? Could he feel the same?