Ok, so I have a lot of ideas for Gravity Falls AUs, so I'm now making a list in no particular order. Here goes.
Blind eye Ford -> Ford went half-way through the portal instead of Fiddleford, who then proceeds to help him with the memory gun and they start the Society of the Blind Eye together (possible Fiddauthor)
Fix-it AU -> my personal fix-it AU, in which the fixing consists of whacking Fiddleford upside the head in 1982, so he goes to save Ford, but finds Stan, they then save Ford (past unrequited Fiddauthor, Fiddlestan)
Zombie apocalypse AU -> in which either Ford didn't find a way to stop the zombies of the kids don't find out about the invisible ink, so canon goes hay-wire at scary-oke, and it's a full-out zombie apocalypse (Stan gets to be badass and save the kids)
Genderbent + Criminal/cop AU -> Criminal fem!Stan reforms to the cop's side of the law when she hears that her twin sister master detective fem!Ford goes missing (in the thrall of criminal mastermind fem!Bill Cipher), she wants to find Ford again, but winds up in a cat-and-mouse game with Ford's closest informant, genius inventor and seller of technology on the dark web, fem!Fiddleford (Fiddlestan, toxic Billford)
Omegaverse AU -> canon divergence the moment Ford falls through the portal. Weirdness leaks over and suddenly everyone gets a secondary gender. (there's some worldbuilding and biology that I'm leaving out here) Canon goes as normal, with the only difference of the secondary genders. The kids go to whom they believe is their beta grunkle Stanford. The only canon divergence is in a tale of two Stans, or soon after that, when alpha!Ford gets his first rut (the constant stress of his multidimensional travels kept him in constant barely surviving mode) and so the kids and Stan have to explain the whole A/B/O thing to him (though the kids aren't present for the explanation of sexual side of the whole deal) and Stan reveals that he's actually an omega.
Portal Grunkles AU -> what if, when Ford was falling toward the portal, Stan threw himself at Ford (trying to save him maybe, or not wanting to get left behind again) and so they both fall into the nightmare realm. At first Ford is pissed at Stan, but out of survival reasons, they quickly make up (there's also bill-induced angst, beacuse Bill). They then proceed to roam the multiverse together with Stan's street smarts and Ford's knowledge of the portal in an attempt to scrounge together a way home. Meanwhile, Shermie went to the shack because Ford hasn't paid his bills in way too long and then the police discovered that he was missing. Shermie takes one look at the shack and decides that he has to live there now. He builds up some kind of business up there (not clear on what). In 2012, the Mystery Twins get sent to their grandparents (or just Grandpa, not clear on that either) but they discover the weird thing in the cellar and their grandpa then tells them about their great-uncle Stanford, who went mysteriously missing 30 years ago (he leaves out Stan, who he believes messed with the wrong guy and got killed at some point), which starts Dipper on an epic quest of trying to find out where and how his "grunkle", as Mabel has started to refer to him, has gone. Then, at some point, there's suddenly a giant boom from the cellar, and when they come investigate, the fabled Grunkle Stanford is standing there. Twice. (might make that two fics actually. one of the stan twins cruising across the multiverse, ending with the moment where they finally get to go home and the other of the mystery twin's summer)
That's all for now, but it's only a question of time until another AU that I might not write pops up in my head.
