this is a totally fascinating topic and i wish i had the law background to fully understand it. there was a new yorker article a while back about an issue like this too -- a playwright had used an actual case as the basis of a play, and there were perceived plagiarism and invastion of privacy issues there. i can't remember what the source material was, though -- a nonfiction book or something else.

because nonfiction versus fiction as the basis for the new work of art has an impact too -- you can't copyright historical facts. which is why the lawsuit over the DaVinci Code books was eventually thrown out, if memory serves.

When you talk about transformative use in regard to copyright, it's such an arcane area of the law. I look forward to learning more as I go. Thanks for pondering this and I know I'll enjoy the comments.