Thanks for the story/explanation. I figured there were Very Good Reasons; I was just curious what they were because, well, I like understanding things. ^^
I still can't read fanfic of my own oeuvre, which makes me sad. But as the lawsuits against Stephen King and Jo Rowling have proved, you have to be able to rigorously prove you never saw someone else's unpublished stuff when they sue you for "stealing their idea." But I am very, very glad that people can write their fanfic and share it now.
...this is tragic.
Is there no way you can structure the Creative Commons license you use such that fanfic authors automatically release all material they use that includes
your work in such a way that you are legally free and clear to use it, perhaps considered to "hold a non-exclusive but irrevocable license" to any "original ideas" expressed in fanfic using your work?
That would, if there aren't still more legal issues of which I'm unaware (and yes, I know there probably are), mean any fanfic writer who tried to turn around and demand "full collaboration" rights would have to either open themselves up to counter-suit for violating your IP by using it without a license, or acknowledge that they used the license you gave out and thus you have full right to use their work however you want.
There are other writers who don't want anyone messing with their world and characters (some have even described a feeling like "being raped" when they discovered there was fanfic about their stuff. On the one hand, I kind of sympathize...but there is no way short of inventing mind control that any writer is ever going to be able to control what happens to his book, world, or characters once the manuscript leaves his hands. So IMHO, I think you ought to just pull on your adult pants, face up to that, and wave goodbye to your book as it heads out into the world. You did your best by it, you tried to make things clear, you gave it the best start in life that you could, but it's on its own now, and you can either make yourself crazy by trying and failing to keep control, or you can do the smart thing and go on to the next book.
I can somewhat understand this, too. I imagine it's at least a bit
uncomfortable for Ms. Rowling to hear about/see/read/whatever fanfics involving her characters engaged in...shall we say morally questionable and perhaps pornographic activities?
Especially the authors who consider their characters in some way to be "family." I mean, we get up in arms over some of the ways family members of prominent public figures get treated just by the media, let alone if "fanfic" authors were to write them into morally-objectionable or horrific situations.
(I'm reminded of a Supernatural sequence of episodes wherein the main characters discovered that their in-universe exploits were the subject of an in-universe novel series, and that a fanfic authoress enjoyed writing sexually explicit versions of "brotherly love." They were rather creeped out.)
Anyway. All I'm saying is, I can understand this concern of some authors, but yeah, the only mature way to handle it is to accept it will happen and move on, ignoring it to the best of your ability. Console yourself that it's not canon.