His misunderstood mistress, Her mysterious servant -A black butler fanfic

Raven Kurobara, 10 years of age and has just become an orphan on her 10th birthday because of assassin's coming onto her families estate and killing everyone in the mansion while she hid in the cellar like her dad said to. After many hours of staying in the cellar, she came out and found her mother, father, older brother, older sister, and younger brother along with the maids and butlers, brutally murdered, which left her alone and an orphan. Now she has to take over her father's position as the only heir to the house of Kurobara and as, "the queens hunter", or more commonly called, "The queens wolf", when the queen calls upon her, she must answer, no matter what. As the only Kurobara left, she becomes Countess Raven Kurobara. She will exact her revenge on the people who have wronged her and sullied the name of Kurobara. She will go to any length to exact her revenge, even if it means giving away her soul to a demon, but will this handsome demon steal her heart along with her soul?