Tremble, Lord of the Rings and Harry Potter fan fiction writers. Fan fiction might not be so legal. I never thought about, assuming that it was, but interesting story from the Literary Review of Canada about debates about the precarious legal position of fan fiction.
Though, you have to wonder, who would sue someone who rewrites Harry Potter from the perspective of Hermione? I guess it’s all fun and games and acceptance of it all until Hermione becomes a mass murderer, thus affecting the value of Potterdom. The extremes would likely rile authors, but up until then, it’s just great marketing for them and fun for fans.