>>103706977There are countless AUs especially since anyone can make one for a one-off. That alternatefalls tumblr has a list of some of the most common shared fan AUs though it's out of date.
What's interesting is that there are seperate Gravity Falls fandoms in dozens of different countries and many have their own exclusive AUs. This is what I saw looking at some worldwide stuff:
Reverse Falls and Monster Falls are the most popular worldwide and sometimes there is more RF than regular fanworks.
China: Vampire Falls with vampire Mabel and Dipper, a very "shape of water" Pinecest Monster Falls spin-off (made before Shape of Water came out though) where Dipper is a scientist and Mabel is a mermaid he's studying and they fall in love, one where Dipper and Bill are serial killers, Ghost Mabel AU, historical China AUs.
Japan: Japan Falls where Stan has a Shinto Shrine, Magical Girl AU, several Loli Bill AUs including one where he's a smug cyclops magical girl, Japanese school AU, not quite an AU but sequel where Bill has to be a maid for the Pines like Kerero Gunso was common.
Korea: Joseon Falls, Swap Falls where Mabel and Dipper are twin demons and Bill is a human, Ocean Falls where they are magical ocean creatures like mermaids, Forest Falls where they are forest animals, many cat and dog AUs (Japan has these too, because kawaii).
Russia: they have many but harder to tell because this is a fanfic based fandom. There is a Russian folklore one with Baba Yaga, an edgy one where they are in an insane asylum, a few where Bill is a hot blonde woman. They also have lots of unique tropes for Reverse Falls (special names for the Reversed characters and such) other places don't have.
Latin America: not quite Gravity Falls since it's a crossover AU but there's a big weird Bad End Friends Spanish speaking following including people who do raps as the characters and make ranking and playlist videos. Some bring in more "bad" GF character versions than just Bipper.
