I disagree. I have actually read neither Twilight nor 50 Shades of Grey, so I base my opinion of what fans of those say. And it is pretty clear from everything I have seen that 50 Shades of Grey would not have existed, much less got published without it starting off as Twilight fan fiction. And to me that is clearly making money from fan fiction. But that is why I see the need for a high court decision to clarify what is actually allowed. (Or better yet a change in international conventions and national laws governing copyright to get them up to date when it comes to current methods of distribution - i.e. the internet.)
50 Shades of Grey was about two (fully human) people in Seattle, Washington, starting a sexual relationship that becomes extremely kinky.
Twilight was about a human girl meeting a vampire in Bend, Oregon, and the long, drawn-out process of them
not having a sexual relationship (or even a romantic relationship) despite both of them wanting to.
The author of
50 Shades of Grey used the names Edward and Bella originally, and presented the story to fans of
Twilight as "alternate universe" fanfiction, but other than the names, it had nothing in common with
Twilight.
50 Shades of Grey appealed to fans of
Twilight, but in every concrete way, it was not
Twilight fanfiction. It wasn't set in the same universe, the tension came from sex happening rather than sex not happening, and it left out the central feature of
Twilight -- that one member of the couple was a vampire.
So in every legal way, once E L James changed the names, it was an original work.
This is why I say she exploited the fans of
Twilight by presenting
50 Shades of Grey as
Twilight fanfiction, and why a lawsuit would have proved little regarding the legality of fanfiction.
50 Shades of Grey was fiction well-suited to appeal to fans of
Twilight, but that's all. If a lawsuit had occurred, it would have easily been deemed an original work based on its content.