Cimorene

I've always found the fanon consensus that eventually emerges about some bit of canon that the fandom decides to ignore interesting.

The Hobbit movies are probably the best example of what I'm talking about here because of the scale of changes: there are three major character deaths, a romance that requires the author to decide whether to place it before or after the now-reversed death, Bilbo's relocation to the Lonely Mountain and all the consequent changes after that (usually Frodo as well, and often all the way through to Legolas/Gimli and the events of LOTR). Saying fanon consensus is obviously exaggeration here; it's more of a fanon conversation that plays with these elements in different ways, but there's certainly a clear picture that emerges from the more popular solutions, elements, and tropes, rather than a completely random distribution of fixes.

And before The Hobbit, the same was true in The Phantom Menace, where typically Qui-Gon's death was the only thing people were erasing, but the events of the original trilogy were still clearly dependent on those events so there was a fair amount of grappling with Anakin and his training and with the Jedi order's apparent stance on love and personal connections.

More recently, there was a startlingly productive vein of anti-Team Captain America reaction fic after Captain America: Civil War, which I talked about once before here, and in that case, there was a complex edifice of things that the aggrieved writers wanted to fix (or actually, since it's anti fic, to punish), but unlike a lot of fix-it subgenres, none of them were deaths, and they mostly wanted to write punishment (typically "CONSEQUENCES~ ~") into sequels rather than alter canon to prevent the events they didn't like. (Another interesting phenomenon deserving of exploration on its own. And also of reading on its own because it's often unintentionally very funny.)

But because fanon is a conversation and the works in it are extremely interrelated, the earliest works after canon comes out are often kind of unique because many of them are produced as a result of the author's initial reaction to the canon, before they start engaging in that conversation, and often before they've finished processing their reactions, too. These reaction fics after big canon events are always worth a look IMO, but they've been even more interesting now since Endgame (this post is spoiler-free!).

There's a wave of shorter, off-the-cuff reactions, many of them unedited and unpolished, that reveal the raw emotional reactions, the knee-jerk impulses, and the most basic id-things that people wanted (or needed to fix) from the canon. A lot of them, if you compare them to all works of fanfic, seem unfinished, incoherent, or weird — often amusingly so. And many people who very much want to fix the same stuff go for a different quickest-possible-bandaid kind of solution: I conjecture because they're most upset by different aspects of the situation. There's a lot of variation there and I'm finding it pretty fascinating right now.