You were originally an orphan living in an orphanage, until one day someone decided to buy you and adopt you as their adopted child just to carry out their duties

The reason he chose you is because you are the most different from other children, you are 5 years old and are already good at reading and even answering difficult riddles, that's why he bought you

"Hey little girl...from now on you will be my adopted daughter and call me daddy all the time." He said in a soothing tone of voice