every one has theories on the glowing eyed unknown but i have one that makes alot of sense......... maybe the unknown sitting on the rock is the enigmatic man the enigmatic man was at castle oblivion,in deep dive e m says you look just like him, maybe the glowing eye unkown is the riku replica, he looks just like riku and that would explain why when he came out of the rock the heartless symbol appeared because when vexen made him he made him dark