I just found this article in the Guardian online about fanfiction, mostly with reference to Fifty Shades, but with a general overview of 'the history' of fanfiction.
I don't agree with several points made in it (and neither do several of the people who have commented on it so far!), but it's worth a read.
http://www.guardian.co.uk/books/2012/aug/13/fan-fiction-fifty-shades-grey Hmmmm... Don't know what made me stop by the Guardian. I was on my way to Amazon to buy more books! *checks time* I can still upload something new to my kindle before bed...