Royal Devil

What will happen if a modern man was transported to a story as an unknown character? A follower of the story 'Who Made Me a Princess' Heusc died because of a virus and woke up at the body of a young bratty prince who had no part in the story. Heusc was forced to enter the Obelia Empire and he was forced into the story... How was he supposed to fit in the story? "What will the plot do to me?"