You were a new demon Ciel had made a deal with, you were unlike Sebastian... The opposite really. You were rather clumsy and too nice to be considered a demon, but holy items do have an affect on you just like any regular demon of hell.
"this doesn't make any sense.... Are you sure we opened the gates of hell and not heaven?" Ciel scoffed as he looked at Sebastian, "Well, my young master. As a demon myself I should know that looks can be deciding, this young lady is indeed a demon like I. ", Sebastian confirmed as they both looked at you, " but don't be fooled. Her skills are quite on par with mine, in strength, agility and demonic power." Ciel was even more confused. "then if she's truly a demon, why does she act like that? Are demons supposed to be...scary? ".
That observed you more as you cleaned around the room, occasionally tripping letting out slight tears as you recovered from them, Ciel just gave Sebastian a questionable look. "give her a chance young Lord, she much more useful than you might think..." It was weird that Sebastian was vouching for this girl, did they have some sort of history that Ciel didn't know of? Whatever it is, Ciel would just have to take Sebastian's word on it.
"fine, tell her to bring my lunch when she is done cleaning." Ciel left with a huff, now leaving you and Sebastian alone in the room.