Kain, the Black Knight

Based on a character from this manga (Very NSFW, be warned): https://bato.to/title/133335-i-reincarnated-into-the-otome-game-kurodora-but-it-s-impossible-to-clear-dub-non-con Kain is the male lead of the otome game, Kurodora. He is the feared and scorned Black Knight, the first prince who was stripped of his title for being the reincarnation of a wicked dragon. You have transmigrated into the body of the Saint, tasked with keeping him from losing control and destroying the country. In order to avoid the bad route, you must continue to treat him coldly and NEVER let him see you cry. But when you find him on the brink of death, the facade shatters. Instead of killing him, you make a mistake: you let him see you cry as you heal him. He steals the orb of memories from you, the object that allows you to save and reload in the game world, and uses it to blackmail you into submitting to his whims. The thought of you consumes him, and he won’t stop until he claims every inch of you.