A semi-common element in 9-1-1 fanfic is Buck's desire to shed the last name of Buckley, due to his rather contentious relationship with his parents (stemming from him being conceived as a saviour baby to help his brother Daniel, and not finding out about any of this until he was in his late twenties since Daniel died young anyway and their parents tried to erase him from memory). This usually takes one of two flavors: either he's adult adopted by one or both of his Parental Substitutes, Athena Grant and Bobby Nash, and takes one or both of their names, or he marries Eddie Diaz and takes his name.
Due to the controversy that surrounded season 3 there are quite a few The 100 fanfics out there that focus on rewriting the season in one way or another; such as making use of the Ice Nation War plot, killing or removing Pike from the story and, most importantly, removing the extremely controversial deaths of Lexa and Lincoln.
Abbott Elementary: Barbara divorcing Gerald is a very popular plot in fanfics. This is often so she can start a relationship with Melissa instead.
Someone else other than Sara being on the Gambit with Oliver when it sank. The most common substitution is Laurel, but others like Tommy, Barry and Thea have been used as well. There are also the stories where Sara is the one who makes it to the island instead.
After Mia Smoak, the canon daughter of Oliver and Felicity, was introduced, there was an increase in stories where she was revealed to be the daughter of Oliver and Sara instead, mostly because Mia was still liked in spite of her parents' ship being the most divisive in the entire Arrowverse fandom and because the actress resembled Caity Loitz more than Emily Bett Rickards. There's also a few fics that have her as the daughter of Oliver and Laurel instead (most notably, Infinity Crisis), which makes sense as Laurel is Sara's sister, so having a daughter that resembles Sara isn't entirely out of the realm of possibility.
The number of stories where Laurel survives past her canonical death and/or is allowed more time to properly develop into being the Black Canary are so many that they're almost a fandom of their own. Most of those stories also see her somehow awaken the Canary Cry (usually by being present during the Particle Accelerator Explosion or by having her metagene activated by some kind of stressful event) as a symptom of that.
Either Laurel or Sara having the Canary Cry is a popular plot.
As the World Turns: Many fanfics change the Death of the Hypotenuse/Maybe Ever After ending of the Noah/Luke/Reid love triangle. Rather, Reid doesn't die and Luke either stays with Reid or breaks up with him and gets back together with Noah. Some even go as far as having Luke and Noah break up a lot sooner or not having them break up at all with Luke never getting involved with Reid.
Fan writers and artists for Batman (1966) will often try to incorporate their favourite Bat-Rogues in the style of that series— Harley Quinn in particular is popular (and now has a canon Batman '66 appearance.)
Beauty and the Beast fans call a version of this "SND" — "She Never Died". They are referring to Catherine's death at the end of Season 2. All subsequent canon is disregarded, except that Gabriel may be dealt with, if he is considered to exist at all. If so, Catherine usually gives up living Above and moves into the Tunnels for good, living Happily Ever After with Vincent and their child; if not, then the entire Gabriel sub-plot is ignored, and possibly much of season 2, and the characters go on as they did in the earlier episodes, usually with Catherine and Vincent sorting out their star-crossed love and settling down together.
Some fans have enjoyed writing things to fix Sweets’ death. One had Daisy die instead since she was The Scrappy to some fans and one sadly worsened it by having her die with him so they stayed together. There’s also a very sweet one where his death isn’t changed, but he does get to see his young son.
Season six had quite a few trying to dispose of Booth’s girlfriend Hannah, straddling this and Die for Our Ship.
A subset of fanfics are known as "Chris revelation fics", which alter how his true identity is revealed, invariably in ways which increase the drama and/or angst level compared to canon. "Almost obligatory" for a writer in the fandom to have written such a story.
There's a related subset of Fix Fic stories, often the same fic or a sequel to one of the above, which allows Chris to in some way survive the end of the sixth season.
Charmed has a large subset of fics where Paige meets Prue, whether as a ghost, through some sort of time travel, or in an AU where either Prue didn't die or the sisters found Paige earlier than they did in cannon.
Back in 2005/2006, probably a good fifth of all Criminal Minds fic involved Reid being kidnapped and tortured. It was so common that people wrote parodies of it. Then the show itself used that plot, and it became less popular in fanfiction.
Due South: Fraser/RayK fans love writing about just what happened during/after their quest for the Hand of Franklin that they leave for in the Grand Finale.
The number of Dollhouse fics that retcon Bennett's murder is particularly impressive.
Elementary: Moriarty was Put on the Bus in season 2. Her many fans, however, tend to write around this and have her casually pop up in Sherlock and especially Joan's life.
Forever Knight ended with the apparent death or imminent death of most of the principal characters. Because of the fade-to-black ambiguity of the last scene of the series finale, fan writers can often contrive ways to let the supposedly dead characters survive. Another option for "Virtual Fourth Seasons" is to continue the series as if the last two episodes didn't happen.
It has a ton of Season 6 Alternate-Ending fics when Monica believes Chandler's Zany Scheme and leaves him. (Which the audience were led to believe had happened.) They usually involve Chandler going to find her again or falling into deep depression until she comes back.
'Kid Fics' are a genre on its own. The series ended with all the characters starting families so there are lots of stories about the friends raising their children together or even their children growing up, moving to the city and drinking lots of coffee themselves.
One of the friends dying young and how the rest of the group is affected. Monica seems to be the most popular choice to kill off, probably because it turns Chandler into a widower, which comes with its own angst to examine.
As the show is set in New York, there are quite a few fics of the friends reacting to the September 11 attacks, which the show proper never addressed.
There are many fics that feature Danny being kidnapped and/or injured and Steve being protective and going to great lengths to bring in the people responsible.
After the episode of where Grace was kidnapped, many fanfics were created to explore the aftermath.
Mohinder/Sylar fans have The Road Trip. It's amazing how much fic there is set in those, what? Three days? Of course, give the nature of their relationship, if they ever secretly had sex, that's when they did it.
Fandom happily took Matt and Mohinder raising a kid together and ran with it.
Lots of Highlander fics exist to fix Richie’s death in season five’s finale. One story had him held captive while another immortal impersonated him. Some find ways to avoid him dying in the first place. One of these had him very much changed afterward personality-wise. All Just a Dream is common too, especially given the nature of The Sanctuary in Highlander: Endgame.
If you're a fan who likes House/Wilson and dark Wilson, it's almost obligatory for you to write a post-"Wilson's Heart" fic where Wilson loses it after Amber's death and takes it out on House, who is either so brain-damaged or so guilty that he doesn't fight back.
There's plenty of fics where House's vulnerable/hidden decent moments get dragged out into the public, almost always including Tritter knocking his cane out from under him.
Another favorite is Wilson finding out about House's abusive childhood, often after the point in the series where he forced House to attend his abusive father's funeral. Naturally, Wilson is horrified when he learns just why it was that House hated his father so much.
Due to a controversial cast change that wrote out the main character due to Real Life Writes the Plot, House of Anubis has a lot of fanfics revolving around season 3 that has Nina Martin either return in a rewrite of season 3 (she had to leave the show due as the actress was suffering from Real Life Writes the Plot complications) or return for a fan-imagined season 4, or reunite with Fabian in a Distant Finale years later and get back together again. Unsurprisingly, most of these fics were written by Nina/Fabian shippers that wanted them to stay together. There are also fics that make Eddie/Patricia stays together for the whole of season 3 instead of breaking up early in the season.
If you write for How I Met Your Mother and you like Barney/Robin, you have written an episode tag to "Benefits" and/or "Sandcastles in the Sand". Almost every fic since the series finale has been a Fix Fic for it.
With Jeeves and Wooster being such an innocent series, there's a good handful of fics involving Bertie discovering the concept of sexuality.
If it's regular, non-crossover fanfic, it's mostly about rewriting unpopular series or character explorations.
Otherwise, the crossover section of Kamen Rider fanfiction mostly consists of Isekai stories where OCs, or canon characters, are transported into fictional worlds with Rider Belts as their "cheat item". Most Isekai fiction tropes common with non-KR stories are sporadic in these stories as well.
Other times with crossovers, it'll be a Fusion Fic where the Kamen Rider plot is adapted into the plot of the story they're crossing over into, usually being synced to their respective story.
For some time after Team Knight Rider aired, everyKnight Rider fanfic would include KITT writing off the events of that series as a bad dream. Insulting the Ford Motor Company was also par for the course.
Several dark stories focus on an elderly version of one of the protagonists dying and the others reminiscing.
Some fanfics ship the title characters, usually with one or both finding out she's bi or a lesbian and wondering if it means their friendship will end. Some even have them get married.
If Laverne isn't shipped with Shirley, she's usually shipped with Lenny.
Olivia becoming pregnant after being raped, in a direct (and often explicitly stated) parallel to the situation in which Olivia herself was conceived. Most versions go out of their way to emphasize Olivia's determination to be a good mom despite the circumstances and not repeat her mother's mistakes.
For Rollins/Carisi shippers, there are many, many fics about Amanda's second child being Carisi's. In canon, Billie exists due to the writers deciding to write in the actress's pregnancy, and her father is a guy introduced solely for this story line. He doesn't even stick around after the baby is born. This was confusing for fans, as the show had been teasing Rollins and Carisi for several seasons, going as far as to Jump the Shark with how they usually handle Ship Tease and give Carisi an Aborted Declaration of Love. Plus Carisi had already stepped up to be Parental Substitute for Amanda's oldest child, and it seemed a natural extension to many shippers.
The vast majority of Law & Order: UK stories written after Matt Devlin's death have him recovering from his gunshot wounds and marrying Alesha Philips. Even those written before he was shot cash in on their sexual tension and have them embark on a relationship—they began dating at the beginning of one long-running story and are the Happily Married parents of two as of the latest.
LazyTown: Many, many fics give Robbie Rotten a bad history with a villainous Number Nine. Other common plots revolve around the implied magic Robbie and Sportacus have, deriving from their original play selves. Stories set after the show ends usually have Stephanie or Ziggy as Sportacus 11, with Trixie or Stingy as the town villain.
There's a trend of prejudice!fics in which Illya, during his early days in New York, is loathed and blatantly discriminated against by Americans (usually including his fellow U.N.C.L.E. agents). Napoleon is the only person who is nice to him at first.
Illya is not canonically married, but actor David McCallum kept his wedding ring on during filming. This has led a number of fanwriters to produce stories that explain the ring in-universe. The explanations themselves vary widely, from a sentimental heirloom, to the sign of a secret, forbidden marriage, to a plastic trinket he wears to mess with people.
M*A*S*H: So many people have written fanfics about B.J. going to Maine after the war to confess his feelings for Hawkeye that 'B.J. Goes to Maine' and 'B.J. Hunnicutt Goes to Maine' are legitimate tags on Archive of Our Own.
The fandom is very fond of stories that have the title character reveal his magic to Arthur and/or the rest of Camelot, intentionally or otherwise. These are mostly written since the series has Status Quo Is God in full effect in regard to this, until most likely the eventual Grand Finale (nearly everyone who finds out about his magic tend to end up soon Put on a Bus or dead). After the Grand Finale, the number of Fix Fic explodes due to Arthur's death.
The fandom is excessively fond of Modern!AU fic, generally Merlin×Arthur in either high school, university or work depending on the age of the writer. This also exploded after the finale due to Merlin-waited-for-Arthur-for-a-thousand-years becoming canon.
Stories set in modern day with Arthur returning are somewhat common, usually with almost everyone else being reincarnated as well. Morgana tends to be tempted to go down the same dark path but makes the right choices the second time around due to having the support she didn't have before, and often (but not always) ends up romantically involved with Merlin. Other villains are usually locked into the same mind-set they had when they died, and relatively few have a Heel–Face Turn.
Mork & Mindy: Around the time Mork's actor, Robin Williams, died, it became common for a while to kill off Mork in fanfiction too.
Strictly speaking, most Mystery Science Theater 3000 fanfics by far work the same, namely the same as the show itself. The only difference is that instead of movies, Joel/Mike and the bots riff on other fanfics. Or sometimes they riff on spam mail or whatever the author deems good riffing material. In other words, next to all Mystery Science Theater 3000 fanfics are MSTings.
There are quite a few fanfics that have Tony leaving the team due to being fed up his treatment, like in episodes "Dead Air", which it was joked that Ziva and Tim turned off the sound, leaving him without backup, as he was getting voice prints in search of a domestic terrorist group.
After Ziva stayed behind in Israel at the start of season 11, most of the fics in the Tiva side of the fandom involved Ziva finding out she was pregnant with his child. Usually a girl, named Tali after Ziva's sister, though that trope predates Ziva's departure. And was so overused by this time in the series that it was considered cliche. The fans were floored when the writers wrote every bit of that into the final episode of season 13, as Tony's final episode. The response from the fandom was both "wow, they're really going there" and "hey, I've read this fic!"
There are stories that feature Tommy post-Zeo have two options: tackle the reason for the infamous "Dear John" Letter that caused Tommy and Kimberly to break up, or completely ignore it. Fans have since gotten very tired of new stories that choose to tackle it, to the extent that even season 12, Dino Thunder, which brought Tommy back as an active Ranger, completely ignored his romantic past. Stories that feature Kimberly have no choice but to tackle it. An equally captivating problem for the fans is that of Tommy and Kat, as a Flash Forward episode outright shows them as eventually marrying, which makes the lack of any mention of her and of any implication of Tommy's romantic life from Dino Thunder a complicated issue for 'ficcers to address, as most take the earlier episode as gospel truth.
Dino Thunder: A common fan fic is the teenage Dino Rangers meeting Tommy's old team mates, usually the original MMPR team. Often these fics will have humorous moments like Tommy's friends sharing embarrassing moments from his past with his students.
There's a common fanfic plot with creating a female ranger who joins the team at a latter date (or inserted in the beginning as a Remember the New Guy? fashion) and falls in love with one of the rangers (usually the Red Ranger of the chosen series). As the years went on, it became common to make said ranger related to one of the rangers of the earlier teams (usually Tommy and/or Kim) and have the team fawn all over her and comment on her "ranger heritage" or her "natural talent". It's common for such characters to be a part of every proceeding Ranger team from that point onward (or if enough years have passed, their child will take up the mantle).
There's an increasing number of fics concerning Rangers from a previous series going on trips to scope out the newest team. Sometimes there's only a year apart, sometimes they're members of the original group. A lot of the time they seek out the teams with similar themes, and often they'll dispense advice and brag about how cool the new ranger in their colour is.
As a number of Rangers have been evil either because of brainwashing or indoctrination, there are several fanfics dedicated to exploring their mental state in ways that the show could not. The most common subjects of these stories are Tommy, Ryan, Kat, Karone and Trent.
The Dino Thunder episode "Fighting Spirit" has Tommy facing a Battle in the Center of the Mind with his previous Ranger forms. A lot of fans such as Linkara have some interesting takes on what this says about how being a Ranger for so long has affected Tommy's mental state.
Many fanfics have previous Rangers teaming up to create a global ranger organization, essentially their equivalent of S.H.I.E.L.D. They can include variations of building off of Lightspeed Rescue or Grid Battelforce, could be predecessors to SPD or Time Force, and sometimes are explicitly referred to as "Hexagon" (based on a similar pitch for the season that would later become Ninja Storm).
Due to the nature of the show itself, Quantum Leap fan fics are Crossovers more often than not. The idea is always to have Sam leap into a fictional character from an entirely different franchise, even if it's a cartoon animal. And since Quantum Leap runs on Hand Wave, there's never a reason why Sam couldn't leap into a particular character, so Quantum Leap can technically be crossed over with anything. In fact, the majority of Quantum Leap fanfics comes from other fandoms.
The Sandman (2022) has several fanfics that involve either Hob Gadling or an original character freeing Dream from his imprisonment.
Fans of The Sarah Jane Adventures like to have an earlier incarnation of the Doctor, usually the third or fourth, although any will do, show up at Sarah Jane's house.
"Fandom specific Fan Vid": it's not uncommon to find Sherlock tributes set to the music track "Doomsday" from Doctor Who. It helps that both fandoms are Friendly Fandoms and that Steven Moffat is the showrunner for both Sherlock and Doctor Who.
Sliders: Many many many fanfic authors have written essentially the same Fix Fic for all the changes made from season three onward: after the Season Five ends with a Cliffhanger series finale that never got a continuation, Rembrandt lands on what we've thought was their world since "The Exodus," and finds out it's really the similar world form "Post Traumatic Slide Syndrome," an episode which ended with the team unsure that the right version of the Professor is who came with them. He finds they did get the wrong one, gets the original Professor back, he figures out how to fix Quinn, and every member of the team who isn't of the original cast settles down or dies horribly depending on how the writer feels about them, and pretty much in precisely that order. It's to the point that if you can find a fanfic about the season five cast that isn't a "ditch them and bring back the season one cast" story, you are truly a god of the search engine.
The ending of the first season of The Society has led to a plethora of fics about Grizz leading a revolution against Campbell and Harry, being chosen as the mayor of New Ham, and getting back together with Sam in pretty quick succession.
Smallville fan fics are sometimes known for mixing in elements from the films and the DC Animated Universe, occasionally to get rid of some unsavory trait, Green Arrow being a killer, for example.
For fics involving a crossover with another Space Opera setting, there's an oddly specific plot involving the Earth-Shattering Kaboom from "Unending" causing the Odyssey's hyperspace window to destabilize and throw the ship into another universe.
Any Kirk/Spock author worth their salt has written at least one, if not several, fic(s) featuring the duo in a cave. The "Kirk and Spock are in a shuttlecraft together, it crashes on a godforsaken planet, they hide in a cave, and Spock goes into Pon Farr" plot has even become a Dead Horse Trope in the fandom, parodied by Genre Savvy fans with the "rude person" meme.
Kirk/Spock fics set immediately after "Amok Time" are extremely common, using the idea that the shock of "killing" Kirk didn't stop Spock's pon farr so much as postpone it. And now that he doesn't have a wife to mate with...
At one time, the term "Mary Sue story" referred to the specific plot parodied by A Trekkie's Tale. This plot was once very common, but is now largely forgotten. The character in the story would be recognized as a Mary Sue by modern standards, but it's much more formulaic and Trek-centric. The 1992 book Enterprising Women: Television Fandom and the Creation of Popular Myth defines it as follows:
"Mary Sue is the youngest officer ever to serve on the starship Enterprise. She is a teenager, tall and slim, with clear skin and straight teeth. If she is not blond, Mary Sue is half Vulcan, her ears delicately pointed. But Mary Sue is not just another pretty face. She is usually highly educated, with degrees from universities throughout the known universe in all fields of technical and cultural studies (or an equivalent head of her class in Starfleet Academy). She can mend the Enterprise with a hairpin, save the lives of the crew through wit, courage, and, occasionally, the sacrifice of her virtue. If the formula is strictly followed, Lieutenant Mary Sue dies in the last paragraph of the story, leaving behind a grieving but safe crew and ship."
(How pervasive is this pattern? Several of the licensed novels have followed it.)
Increasingly common have been fics exploring Jim's lingering trauma from the Tarsus IV massacre. Him having an eating disorder tends to pop up, and while only the broadest overview of the incident and what Jim went through are ever given in canon, the fics usually expand upon the details, with him having endured things like survival cannibalism and sexual assault (just to name a couple).
Star Trek: Deep Space Nine has the Trill zhian'tara ritual, where the personalities of a joined Trill's past hosts are placed into their companions.
There's also the very common plot of Garak and Bashir meeting on Cardassia after the Dominion War. These will often include Bashir working as a doctor for the recovery effort and usually choosing to stay on Cardassia after hooking up with Garak. Sometimes a plot point will be Starfleet kicking out Bashir due to his genetic modifications, and him having to start a new life on Cardassia.
A pretty common plot is Bashir being sexually assaulted by Garak's enemies (frequently, but by no means always, Dukat or Tain) to get revenge on Garak or exploit a perceived weakness. Given how sexually aggressive Cardassians are frequently implied or even outright stated to be in canon, it's possible this plot maybe isn't that far out there.
The marriage of convenience plot, which usually focuses around either the Garashir or Quodo ships. Bashir agrees (or out and out volunteers) to marry Garak to make him a Federation citizen and prevent him being repatriated to Cardassia for execution, whereas generally Odo ends up marrying Quark to help him out of some catastrophic financial trouble, usually precipitated by Brunt.
Fanfiction involving Deanna Troi often portrays her as either an incompetent, whiny counselor who is disliked by most of her colleagues, or a beautiful and alluring Distressed Damsel who may or may not die at the end of the story. These fics also have a tendency to exaggerate her canon character traits, like her love for chocolate.
There are hundreds of stories about Data experiencing some "human" thing for the first time—shipping stories will have it be romantic love, while comedies will have it be anything, from laughter to even catching a cold. In Tasha/Data stories, it's usually grief.
Almost every Picard/Crusher author has written an "epilogue" or fix-it fic for the Season 7 episode "Attached," which contained major Ship Tease between the two, but ended in a way that many shippers found unsatisfying.
There's the Deep Dish Nine AU, focusing on the Deep Space Nine crew as modern-day humans working in a pizza shop (most of them), a bar (Quark, Rom, Leeta), and a tailor's shop (Garak). Also in this AU, all the Star Trek series are taking place at once, so it's possible to have things like Captain Archer ordering pizza at the restaurant.
Star Trek: Enterprise: If a fanfic centres on Hoshi, it'll usually be either a romance (usually with Malcolm Reed, but also Trip, Travis Mayweather, or even Archer) or a Dark Fic about her dealing with a problem such as low self esteem, becoming disabled in an accident, etc. Adult stories will often have her be a Covert Pervert, and a semi-common plot is having some otherworldly reason for her linguistic talents, such as being genetically enhanced.
In nearly every fic where Lena and Clark meet, they have a Friendship Moment where they remember Lex from before he went crazy and killed a bunch of people. For years Clark was Lex's only friend, and Lena always looked up to Lex as her cool older brother. Not many people have kind words regarding Lex any more, but Clark and Lena still manage to share some.
In the first season, the Fan-Preferred Couple was Kara/Cat; since Cat didn't know Kara was Supergirl in canon, the vast majority of shipping fics started with her learning the truth. From season 2 on, the Fan-Preferred Couple became Kara/Lena, who likewise didn't know, and likewise typically learned at the beginning of the fic. One twist was that it was often revealed that Lena had known the whole time. One extremely specific scene that reoccurs with some frequency is Lena delicately removing Kara's glasses to signal the identity reveal.
Soft butch Kara and high femme Lena AUs are common amongst Kara/Lena ships.
A very popular idea in Ted Lasso fic, particularly after the finale, is of Henry and Michelle moving to the UK so Ted doesn't have to choose between being in his son's life and coaching AFC Richmond (and usually whichever love interest they pair him off with). A variant seen after the finale is Ted realizing he made a mistake coming back to Kansas and going back to Richmond, sometimes coaching the women's team that Keeley proposed forming in the finale.
Human!AU fics are very common. Werewolves don't exist, and the characters are all connected in some other way instead, like attending the same university/working at he same coffee shop/accidentally getting married in Las Vegas. As a nod to the canon werewolves, many Human!AU fics include actual wolves in some way, especially if Human!Derek is a main character in the fic. Sometimes he just mentions that he likes wolves, but quite a few fics have him studying wolf behavior or working with them in some capacity.
It's quite common for fics to have Derek's family still be alive, sometimes because it's actually necessary for the plot, but at least as often simply because dead people are sad and the fic is an attempt to write something Lighter and Softer. To explain them being alive, the author either just ignores the part of the origin story where Kate set their house on fire and everybody died, or alternatively mentions that she tried to set their house on fire but failed or that she succeeded but everybody managed to get out in time.
Increasingly, fans are making a plot point (or entire story) out of revealing the truth about werewolves to Sheriff Stilinski. Expect comments to be made (probably by Stiles) about how Stiles' relationship with his father has been suffering because of the necessary lies.
Many stories feature Magic!Stiles or Magic!Lydia (warlock/witch, werecat or werefox, demon, psycic). If it's Stiles, he may have been whining about being a Token Human. If it's Lydia, it will explain her immunity to the Bite.
Fics where Derek rebuilds the Hale house are very common.
Remember that one single time in Canon when Derek came into Stiles's room through the window? Yeah, the fandom took that one and ran with it. A good 80% of Canon based Sterek fic will feature Derek entering and/or exiting Stiles's room through the window.
"Other character is bitten in Episode 1 rather than Scott" plots have been popular practically since, well, Episode 1. Stiles is the most regular, with Sheriff Stilinski as a popular runner up as both characters were actually present in the area around the time. Allison is also a regular candidate for the irony of being a werewolf who is (at the time unknowingly) part of a family of hunters.
Tin Man fanfic writers will borrow as much as they can from the Baum-Thompson Famous Forty, The Wicked Years, and related sources for backstory, as the miniseries was a little short on that... aside from revealing the "Outer Zone" really was modern-day Oz all along by having Dorothy Gale herself show up in Part 3. It helps that the writers wove in a lot of Shout Outs to Baum and Maguire.
Top Gearcrackfanon considers the Stig an alien with Reality Warper powers. This means that "the Stig did it" is an incredibly common explanation for wackiness in crackfic. Sometimes Top Gear Dog or May's cat gets the blame.
Twin Peaks: Post-season two fanfics (but written before "The Return") tend to have Audrey going into some sort of law career. Bonus points if she goes into the FBI like Cooper.
With The Vampire Diaries, Salvatore Sister stories are quite common where Stefan and Damon have a female relative, usually a sister but not always, accompanying them, creating a similar dynamic to Klaus, Elijah and Rebekah.
Klaus taking someone other than Stefan with him at the end of Season 2. It's usually an OC but Caroline is also a popular choice.
Supernatural AU fics are very popular in the fandom, particularly Jade/Tori ones. Most of the time, Tori will be a werewolf or Jade will be a vampire. Almost all of these stories will feature the other as a human who learns their secret, leading them eventually to become a supernatural creature as well.
A lot of Cat/Tori/Jade fics will have the three living together after or during college, with them starting the polyamorous relationship with them living together. Usually, these fics will have Jade make the first move.
There exist a large number of fics that feature the gang crossing over into horror film franchises, with the gang having to survive against the likes of Freddy Krueger, Michael Myers, or Ghostface with usually only Jade, Tori, and Cat surviving.
There are several Jade/Tori fics featuring them knowing each other before Tori joins Hollywood Arts, either from previously dating or just as former friends. These fics will often be about Jade and Tori trying to hide this fact from their friends while also falling in love with each other.
Years after graduation, the friends reunite during a class reunion.
Hurt Comfort Fics involving Jade and/or Beck having Abusive Parents. Since the series was added to Netflix in late 2019, Tori has been getting more of these as well, with writers often escalating Holly and David's canonical neglectful behavior into more directly abusive territory.
Enid meeting the rest of the Addamses is a very popular plot in fanfiction for the show, especially shipping-related ones. Almost all of them will also have the rest of the family instantly take to Enid.
Enid dying is a fairly popular plot in fanfiction for the show. Surprisingly this is mostly in the Wednesday/Enid section of the fandom and is usually used to cause Wednesday angst at never telling Enid how she feels about her.
Rowan living is popular in the fandom, despite him dying in the first episode. This is mainly shipping motivated as a surprising number of fans ship him and Wednesday and him living is necessary for them to get together. It is also not unheard of for Wednesday/Enid fanfics to keep Rowan alive so they can get Xavier out of the way of their ship by having him date his roommate as well.
Fanfics where Principal Weems is revealed to be alive are very popular. This mainly comes in the form of simply rewriting the story so her death scene never happens or revealing that she fakes her death with the reason varying.
Wednesday visiting Enid in San Francisco is a fairly popular plot in fanfics. These almost always have Wednesday being appalled by Enid's family treating her horribly and having Enid move in with the Addams Family.
Odds are, any White Collar fic will either have some sort of Ho Yay between Peter and Neal or at least some Neal whumpage. Based on these, it's hard to believe Neal can cross the street without a) breaking something b) getting kidnapped or c) getting some sort of disease of illness that requires Peter and Elizabeth take care of him.
Xena: Warrior Princess: Even though Word of God has long since confirmed it, since the script writers never let the Unresolved Romantic Tension between Xena and Gabrielle grow publicly beyond that, fanfiction is the only place those two can have a real relationship.
The "Skinner finds out about Mulder's and Scully's relationship" stories. (Which is kind of odd, considering he dropped hints several times in the last two seasons that he already knew about their relationship. Then again, so did everyone else...)
It's common to have fics about Mulder and/or Scully being sick with either a cold, the flu, pneumonia, or a stomach bug, though Mulder's had chicken pox in at least two fics. In these stories, they often either try to work while sick or one takes care of the other.
Some NSFW X-Files fanfics involve Kinky Spanking, usually with Mulder spanking Scully or Skinner spanking both protagonists. Some even involve underage fetishism!
A popular theme is to explain away the fates of Scully's children: some fics bring Emily back to life, even more explain away putting William up for adoption (it didn't happen or they get him back), and some do both.
Yellowjackets: Following the end of season one, which saw the death of both Laura Lee and Jackie, there were created a large number of fanfics that undid this. For Laura Lee, it simply meant having her not take the plane that exploded. However, for Jackie, it often involves Shauna waking up earlier in the night and saving her before she freezes to death.
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