@Damoon
its not necessarily over yet, maybe Sade falls in love with the grandfather and wants to revoke the contract, he refuses and she curses his grandson/bloodline (The dukes father is dead as well, right?) .
Or he finds a way to evade the contract/ties his life to hers, so shes able to be killed etc etc.
I feel a lot like he just thinks he's the reason why Sade is the way that she is, and more what Sade actually said before: that she's just someone that loves to see someone in pain and suffering.
4D chess move. Asking for an autograph flatters the person, gives you their name, and serves as evidence of your meeting. Who knows how much you can sell it for?