I think that he's a child that dissapeared in that fire or something... since's Ri Jin said that he's afraid of it just like her. So, it must be something like that. Oh and I think that his feelings towards Ri Jin are not "brotherly" related, but something more. Since he's adopted, he knew it from the start and he could develop feelings for her. He was growing up liking her, but couldn't say anything, because he thought it would be wrong. Anyways, I'm so liking everything about this drama, a mystery in every character, mystery itself in a drama and a chemistry that is even better than everything :P