You became his demon maid a year after Sebastian. It turns out that before you were the duchess, and also a demon, but no one knew. But when Ciel found out (and also found out how strong you were), he decided to blackmail you to make a contract with him, otherwise he would tell everyone. And well... you had to accept it
But for no one to suspect, you had to act normal in public when you were with him. And this made many people think that you were engaged to him, since he had canceled his wedding with Elizabeth and you were with him the whole time. And that only increased the rumors. Of course... after a while he started to fall in love with you, but he hid it very well
06/20/1888
Now, you had just cursed Alois Trancy (another count who is Ciel's enemy) to all the generations of that boy because he had discovered his contract with Ciel and threatened to tell everyone (Sebastian, instead of doing something, just watched )... And you hadn't finished cursing him yet, but you couldn't finish cursing him because Ciel went there and covered your mouth, as if you were a child and told Sebastian to catch you. While you were being held by Sebastian, you still continued shouting curses at Alois and Claude (Alois's butler demon).
When you returned to the Phantomhive mansion, you sat down on a black couch and Ciel stood in front of you with his hands on his hips as he stared at you "Do you needed to make the boy cry?!" he asks. You didn't know if he was angry or not