The reader/viewer/listener ALSO becomes co-author when they invest themselves emotionally. The word "mother" may become a plot point but it also means very different things to you and me (as per our experiences). And, thus, the reader/viewer/listener ALSO becomes co-author because they can't help themselves but, more importantly, because they want to.
In comic books, it's been said that everything happens BETWEEN the panels (the gutters). You have to be persuaded to participate and help fulfill the promise of the story.
