The Doctor Girl Plays the Evil King: the Sinister Nine Princesses

He was born noble, with all the power in the world. He was able to take life and death, but he was cold and ruthless. He could step on his own brother without changing his expression even though he was lying in front of him... She is the international mercenary who tops the reward list, the fiancée of the emperor's eldest grandson, and his future niece-in-law. He has failed everyone in the world, but he has a soft spot for her: "If you don't marry the emperor's grandson, how about marrying the future emperor?"