Heaven Knows I'm Wicked - Sebastian Michealis Fanfiction

You are a hybrid born to an angel and a demon, who travelled from France, where you made up your identity, Gabriele De la Croix, to Britain as a young man, to join the Earl of Phantomhive, served by a mysterious yet familiar man coming from the depths of hell. You/Gabriele, already aware of the Earl's acquaintances with inhuman beings, are interested in his motives behind such risky decisions, like, for example, his choice of sealing a contract with a demon...

However, things turn out more awkward when Ciel and the whole Phantomhive staff find out that you are a lady with a manlike physique and after thinking of hiring you as maid, decide to make you the second butler of the Phantomhive household. Despite the number of hints, nobody was aware of the vulgar creature you are. Nobody except for Ciel and especially Sebastian...for the safety of the Phantomhives.