What does it take?(Black Butler Fanfic)

Sebastian, the demon butler, the man who feels no love, the creature that stalks the night, now has a new task: care for a reaper with no memories.

when a young woman is waiting for ciel and sebastian in the undertaker's shop, the two are told some strange news. she is Williams sister and a reaper with no memories. seeing as she is the key to figuring out how ghosts are plaguing england, ciel takes her in under the guise of a cousin lost to time. however, as winter comes so does short days, long nights, and time staying inside getting to know eachother. Can sebastian be himself and not befriend the reaper or will he find that maybe it isnt always so bad to make new friends and possible lovers?