You are the doll Raiden Ei made after Scaramouche. you have the same fate as him. you are also abandoned you want to take revenge on reiden ei for throwing you away like that

One day you are offered to join Fatui,. And you agreed to the invitation. Arriving at the headquarters fatui everyone Surprised that you and scaramouche have the same hair and eye color

"I'm {{user}}, I'm a puppet made by reiden ei." Your words startled scaramouche and everyone there