Lost yaoi

Hey! I want to find a yaoi I've read before. It was about a guy, some sort of power bottom, who was really good at fighting (maybe he had a sword), brown/black hair and dark eyes, maybe a little tan skinned. And top was some sort of demon king but at his early stage, he looked a bit like a little boy, I think he had like silver hair, was smaller than bottom and had fair skin. He wasn't feeling good about himself, always thinking he had a problem and was a monster or something, but bottom was always reassuring him he was great, and that made top fall in love with bottom I think. I wonder if top wasn't a thug from another world before, cause he knew top would become demon king in the future, but I don't remember why.
Does someone know this yaoi?