So, browsing Reddit, I found this, a comment from someone involved in the Twilight fanfiction community who saw the rise of FSOG, and who 'helped' propel it up Amazon's bestseller list. It's actually pretty interesting, looking in from the outside. We have the perspective of someone invested in multiple other fandoms, which makes it even more interesting, I think. If you go down the page a bit further, there's stuff about Cassandra Clare and HP fandom, and a few other tidbits. The author of the main comment keeps posting further down the thread, and there's interesting conversations going on. It's worth a read through, at least.