My personal view -- and by personal I mean it is a view which pertains only to such things as they affect me -- first. So everything I say for the next few paragraphs is specifically about my work, or responses to my work.
I find it enormously flattering that something about my work speaks strongly enough to some people that they are compelled to write about those elements. I adore my characters -- pretty much all of them -- and I don't, umm, write a lot of sex, and much of the relationship stuff is subtle enough that even my mother missed it. I'm not sure how much room there is in the cracks of the story -- I tend to think that it's the books in which there are obvious wide and undocumented story spaces that lend themselves best to fanfic writing -- but I don't write fanfic, so what do I know? (Yes, I invite comment).
I'm perfectly happy to have other people write fanfic, and I find the fact that some people do want to do this flattering. I don't have any desire to read what they've written, however, and not just for legal reasons (as in, to avoid later being accused of somehow stealing their ideas, which did happen once, and caused a lot of authors who had previously turned a blind eye to turn a legal eye in its place); these characters have an arc and a life that's entirely on the inside of my Byzantine mind, and while I'm happy that they have an effect on other people, I like to keep that effect and my own sense of who they are completely separate. I don't want to have the "but they would never do that" reaction, because obviously -- to the people who did write the story -- the characters would.
This makes me somehow feel that I've been incompetent; that I've failed to write the characters in such a way that they're clear enough that this would be obvious. Which I realize is entirely beside the point. I'm not a good judge in that sense because I'm entirely too close to the characters. So the reading of secondary creation? It's not something I can reasonably do. I'm happy if others can, and if they build a community on that, even in a small way, that's fine with me; I can't be part of it, but I don't hate or decry it.
I have a different reaction to non-written things based on my work.
Someone recently gave me a CD of recorded variants of a song that she'd written; it's based on lyrics in one of my novels, and I adore it. I listen to it sometimes before I write because there's a sense of pride -- if that's quite the right word -- that comes when I realize that this music was inspired by something I created. It's like a gift in ways I can't explain. It would never have happened if I hadn't written these books. I would never have met the person in question, if I hadn't. And it's something I could never have done for myself; I'm not so musically inclined.
Some fan art has also been done, but I've seen only a little of it; someone sent me a "chibi diora", which I'd use as an icon if I had any graphics ability at all (I generally pass on all such task to my son's godfather; I'm willing to keep an network up and running, but I'm not willing to tangle with Adobe software; my
I find the fan art interesting because I'm not a visual person. It takes an enormous amount of work for me to see things as I write them; I have to externalize them, and I tend to write from a very internal perspective. When someone paints or draws their vision of a character, it doesn't clash with mine because I so seldom have a full-blown one; there are details that are important to me, but not so important that they destroy my curiosity or even enjoyment.
So. On a purely personal level, it's all good to me.
My professional view, however, is that my personal take is just that -- personal. I have no particular contempt for, annoyance at, or in fact, opinion on any other writer's views. If Robin Hobb emphatically states that there will be no fanfic about her worlds, that's her right. Actually, I'll take that back -- I do have an opinion (yes, yes, I know, that silence is not the silence of shock or surprise).
I believe that, in the case where the creator of the primary universe has so clearly stated her preferences, they should be respected. If, in theory, the drive to create works aligned with a world comes from the love of the world created, I believe that some deference is owed the creator of said world. Hobb is my example solely because I happened to be going through her web-site FAQ looking for information about her forthcoming novel for the store. There are plenty of other authors who have the same strong attachments to their characters and universes, and who decry the writing of any fiction in those universes, or about those characters, that doesn't originate from them, or through them.
That's their right. In speaking of my own preferences or opinions, I have no intention of stepping on their feet, or somehow lessening the respect I have for the way they exercise their rights. If they find it less then flattering, or even threatening (I realize that the whole copyright question is grey, and different lawyers fall on different sides of the argument), I think they have the right to do what they have to do to be able to sleep at night, as it were.