Union Of Desire (A Sebastian Michaelis X Reader LS)

She's skillful, dauntless and quiet. This isn't surprising considering for someone with her disturbing past.
Yuna Mavings, she was born something special, but something completely dangerous as well. People never even get close enough to people like her to get to know her. She was born a tigress demon, a demon that has cat ears and a tail. Kind of like a neko, but she has a temper that shows when you mess with her or you get on her bad side, she has skills that can kill. She had deadly claws that materialize when she's angry, but people always think her nails just grow faster than normal people. God people are dumb.
But when she is kicked onto the street and left forever, she meets a kind woman named Meyrin who takes her back to her manor and she is offered a job as a maid. But she meets a certain butler, he immediately gives her the nickname of 'kitten' but when she tries to keep her feelings at bay, she can't but what happens when she gets to go to London to solve the Jack the Ripper case? Will she let her true side show? Or will she manage to stay in control of her tigress?
(Takes place at the beginning of season 1 of Black Butler)