A couple terms to understand before we begin:
Fanfiction: fiction written by a fan of, and featuring characters from, a particular TV series, movie, etc.
Canon: the works of a particular author or artist that are recognized as genuine
Headcanon: Elements and interpretations of a fictional universe accepted by an individual fan, but not found within or supported by the official canon
Fandom: the fans of a particular person, team, fictional series, etc., regarded collectively as a community or subculture
OK, so Harry Potter. The 7-book series that defined a generation of book lovers, and movie-goers. In case you live on Neptune and don't know anything about the books by author J.K. Rowling, the stories follow the life of a young boy named "Harry Potter, a boy who learns on his eleventh birthday that he is the orphaned son of two powerful wizards and possesses unique magical powers of his own. He is summoned from his life as an unwanted child to become a student at Hogwarts, an English boarding school for wizards. There, he meets several friends who become his closest allies and help him discover the truth about his parents' mysterious deaths." This is Google's summary, and to a longtime fan it pales in comparison to the vibrant stories themselves, not to mention the stunning fandom that has sprung up around it.
The Harry Potter fandom (sometimes affectionately referred to as Potterheads) is one of the oldest fandom communities, and one of the richest in terms of material. The Harry Potter universe has expanded to include: seven books, eight movies, spin off textbooks, a new spinoff movie, podcasts, a theme park, Pottermore, the Harry Potter Alliance, a stageplay released just yesterday (July 31st), and an online community of fanfiction writers, fanart creators, and so much more. Through her books and the additional information she gives out, J.K. Rowling has created a rich and wonderful world that fans are always looking for new ways to explore. One of the most common ways fans participate in fandoms is by writing fanfiction. For the Harry Potter fandom, this often takes the form of prequel stories, about the Marauder generation (the generation of the parents of the main Harry Potter characters). The Marauders have a massive influence in the books, but we don't get to see much of what their time at Hogwarts looked like. Thus, the fanfictions. And oh, how they've grown!
Given so much time to write these stories, the fanfiction about the Marauders generation has become distinctly well-developed. Even to the point that the vast majority of fan authors adhere to the same headcanons to base their stories off of. It gives a sense that if you put all of these fictions together, you'd be able to read them as a complete story without any confusion, because they are all built on the same foundation.
Now, with "Harry Potter and the Cursed Child" released on Harry Potter's would-be 36th birthday, and "Fantastic Beasts and Where to Find Them" coming out, some readers are anticipating Rowling's next project to be a prequel series or trilogy, surrounding the Marauders. This is despite her most recent comment: "we're done." Some still hold out hope that this comment specifically about Harry's story being over doesn't extend to the Marauders.
There's just one problem though. With all of the fanfictions and this widely accepted headcanon that have been created, many fans have become attached to the way they've written James Potter, Sirius Black, Remus Lupin, Peter Pettigrew, Severus Snape, Lily Potter, and other characters. They've crafted their own canon, and it's amazingly well put together for being created by thousands of different writers across the world.
So the fear is this: If J.K. Rowling writes a Marauders story, and it's different from the way we've written it, does that strip the value of the fanfictions? Does that mean we're to disregard the years of worldbuilding done by fan authors, in favor of an official canon? Not to mention that she's one of those wonderful authors who encourages fanfiction, and actively participates in the community by responding to popular headcanons and fan theories.
These are questions that the fandom will have to wrestle with if Rowling does in fact publish any canon Marauder-generation stories. But I'll give you my thoughts for now.
Fanfiction is the highest praise an author could ever receive. Not only did someone enjoy your book, but it inspired them to the point of them sitting down and purposefully crafting out their own expansion of the universe. Your story filled them with enough passion to pour out onto a page and send out into the world, bearing their own thoughts and interpretations. Could anything be better?
The value of fanfiction is not necessarily in whether or not it adheres to the canon. The value, instead, is in the passion and the community that it inspires. In that way, this universal headcanon that has been affirmed by Potterheads worldwide will always have a place in our hearts. It means something to us. And whether Rowling's writing, whether it follows similar tropes or goes a completely different route, will never negate that.
