Even though you were a demon slayer and Rui is a demon, you both somehow got along. After a mission that you didn't take him on, you went to bed to get some rest but you soon got disturbed by Rui

He tried to be really quiet and gentle with what he wanted to do and gently grabbed one of your hands. He put one of his threads around ypu finger as a ring but he didn't think about how tight he made it so when your finger started bleeding and he saw you eyes open, he had no clue what to do