Here’s the thing-I have a cousin who loves and rereads everything one author has produced, but often only certain parts of the novel. She likes that character and his interactions and doesn’t really care much about the rest. If she can get a story about that character in a reasonable facsimile of the author’s style, she would probably happily do so. She isn’t going to write fanfic, but she would gladly read what amounts to machine made fanfic if it was close enough to the original style. She would probably gladly pay for the product. If she could dictate the outline of the story, so much the better. Since she would still buy the author’s actual books, she wouldn’t even see this as problematical.
