Fanfic is, at heart, a derivative retelling or restoration of a story that has already been published and distributed. It can be a personal experience, and fic can be private and unshared, relegated to static pieces on a desktop, or it can be posted in a space where the fandom at large can read and view it. The communal nature of fandom, and specifically fanfic, which can create additional material for consumption beyond fanart or fanvids, creates massive communities of creators, writers, and consumers within fandom.
When a consumer/creator fandom is especially active, such as Star Wars, Harry Potter, or Star Trek, there will naturally be cultural aspects of fandom that affect fic. People who are in fandom will have positions on shipping, critique, and how to best portray certain characters. Tropes and common themes will develop in certain fandoms. For example, common tropes in the Harry Potter fandom include “Aurorfic”–where fic explores the lives of one or all of the main trio after their adventures in Hogwarts while working as Aurors–and “Re-Sorting AU”–where a fic will write a what-if scenario exploring what would have happened if Harry had actually been Slytherin, or Draco a Gryffindor.
Fandom culture is fascinating and ever-changing. There is a subsect of the Sherlock fandom that firmly believes that they are involved in a game with the show runners of Sherlock, in which the show runners originally meant to make the gay pairing of Sherlock Holmes and John Watson canon, but were silenced by the influence of BBC. These fans call this the Johnlock Conspiracy, and it centers around the idea that there is a final episode that was never aired that canonizes the pairing. Fans believe that show runners hid clues to the ship in each episode, and that if they uncover enough of the clues, they will be shown a way to access this episode, colloquially called The Lost Special.
It is natural then, that a culture catalyzed around such a massive media success will include fans that have different views on aspects of the source material. Using Harry Potter as a reference again, there are a group of people who ship Harry/Hermione, and a group who ship Ron/Hermione, and while often these groups are disparate and do not usually interact with each other, there can be fandom feuds that occur over the ‘rightness’ of a certain ship over another.
If this sounds petty to you, you are not alone. Many members of fandom think that these sorts of ‘ship wars’ and controversies are not productive and often damaging to fandom culture. However, we cannot discount these fandom arguments, as they are so intrinsically tied to the ways in which people relate to and connect with the things that they love and pour so much of their heart into.
Fandom critique of fandom has always been around. There are records of philosophers in ancient Greece arguing over whether or not Achilles was a top or bottom when having sex with Patrocles. Fandom culture often takes on a life of its own, separate from the original work that inspired it. I know quite a few people who saw fanart, started reading and writing fic, and then watched the source material movies.
There is also a genre of fanfic that is written in direct response to other fanfic, or in response to fandom itself. It will use fandom tropes, controversies, and popular fic to create another piece of work that directly addresses another part of fandom, where the understanding of the fic does not come from knowledge of the original material, but from fandom and community knowledge. One of the best and most well-known examples of this is The Very Secret Diaries, a Lord of the Rings diaryfic inspired by a brief mention in another piece of fic, wherein Legolas steals Aragorn’s diary. This led to the natural question . . .what on earth did Aragorn write in this diary?* 
There is a lot of satire inherent in fanfic. The very existence of fic is reclaimatory and subversive, and it lends itself very well to poking fun at the source material. However, when fic turns in on itself, and begins to address issues within a fandom, the satire-of-satire nature of this sort of fic can be extremely damaging.
Many issues in fandom are so divisive that often bringing up the topic results in little dialogue, and is reduced to camps divided, shouting at each other via text messages. This is not really a solely fandom problem, as any Twitter user can tell you what happens when an Onion article is taken seriously, or a Borowitz Report strikes a little too close to home.
A piece of fic that has come up time and time again as a subject for debate is the iconic My Immortal, which people have argued about for years. It is either the worst fanfic ever written, or the one that satirized fanfic the best. I remember reading it as it was being posted, and I personally believe it to be a very intentional satire of Harry Potter fanfic, and the way that female characters were written at that point in time. No matter what your take on My Immortal, it stands as an undeniable mirror for the other fanfic in the Harry Potter fandom.
One clear example of satirical fanfic is the three-part series The Most Unproblematic Series Ever, which is less than 300 words and tangentially addresses and pokes fun at a lot of the negativity and upset in fandom over Star Wars ship wars, and how characters of color are represented in fandom. Nobody would leave The Force Awakens and think to write this. It’s in clear and direct conversation with fandom as a whole, which is made obvious by the comments on the fic.
Tying all this together, there is an interesting dichotomy in between fandom and fanwork, simply because people will all take in the source material differently, and when shown discrepancies in opinion, it can be personally affecting. So many people care so much about their fandoms that it’s hard to stay objective and learn from other parts of fandom. Satire is often lost in fandom, and is thus extremely rare. There is merit to the theory that all satire produced in fandom circles is in bad faith, as it is usually poking at another sect of fandom that is perhaps even more excluded than the satirist.
Satire usually understands and provokes the overarching powers of oppression and subjugation by making them into the surreal and unbelievable, but when fans turn on their own fandom–whether through a casual lens like Unproblematic Series or a much more damaging and obliquely racist take, such as Fences—it doesn’t serve to shine light on how fandom can improve, but rather highlights the negative aspects of an online community of people who, at their core, just want to enjoy things. This is not to say that satire is an inappropriate response, but rather that fandom satire is almost never aimed at critiquing a fan’s own experience, but rather the experiences of others.
So how does fandom self-critique? The short story is that fandom usually doesn’t, it just subdivides further into niche categories where people congregate and collect their own fic catered for their own interests, without any real inclination to move fandom forward in a ‘positive’ direction. Fandom is not really a place for collective discourse, but rather it serves as a place for people to explore their own desires. Because of this inherent siloism, the essentially critical nature of fandom, and each fan’s ability to modify their own fandom experience to reflect a certain viewpoint or story line, there is no real way within the current fandom model to produce satire in a way that can combine humor and critique constructively and respectfully. Each attempt to revise fandom will be seen as an attack, and every fan will bring their own experience to the table, which leads to a feeling of personal offense when any other fan attempts to point out problematic behavior.
So what now? In order for fandom to evolve it needs to engage in a dialogue that directly addresses the nature of privilege and power both within and outside of fandom. While this might not ever happen on a large scale, I believe that fandom meta, discourse, and the rise of chat groups on platforms like Slack and Discord will lead to a more comprehensive understanding of the emotional, invested fandom. Fandom is, at heart, for and by the fans, driven by a need for more, to address a lack in material. I hope that in the future, fandom as a whole strives to make fandom a more inclusive, understanding, and accepting place for all fans.
*A note on this fic. It was written by known/suspected plagiarist Cassandra Clare, of Shadowhunter fame. However, this piece of fanfic is hilarious and I highly recommend any Lord of the Rings fan read it.