Gravity Falls reacts to...

Monster Falls

Monster falls is an AU which claims Dipper fell into a magical stream and ended up infecting Gravity Falls turning them all into monsters based off of their personality. It also is argued that the events in "Gideon Returns" never happen in this universe. 

Dipper "So it's my fault that everyone turns into monsters."

Mabel "No it's not Dipper."

Shinshinjane "It was only a bad coincidence that it happened, and Stan would have taken the water and sell it to the town as a product of mysteries' bottled water."

Stan "Taken water from a stream? Maybe. But selling it to people of gravity falls? eh also maybe."

Ford "Dang it Stanley! What went through your mind when you sell that cursed water?!"

Stan "It never happen Poindexter!"

Shinshinjane "It's true it never happened, this is just an idea of what you guys would be like as  mythical creature monsters. And here's a list."

Dipper Pines = Cervitaur

Dipper "Part deer? What's so special about that?"

Shinshinjane "I like to think of it as a wise animal and knows everything around the forest. It also reminds me of the Forest Spirit or Yakul from 'Princess Mononoke'."

Dipper "Huh, I never thought about it like that."

Mabel Pines = Unicorn Centaur or a Mermaid (She is imagined differently throughout the fandom)

Mable "GASP!!! Aaaahhhh! Oh my gosh! I'm a unicorn or a mermaid! This is the best day of my life!"

Stanley Pines = Gargoyle 

Stan "A stone monster? I can live with that."

Stanford Pines = Sphinx

Ford "A sphinx. I can see that as my personality."

Soos Ramirez = Golem

Soos "So like a clay monster, that's pretty cool."

Wendy Corduroy = Werewolf 

Wendy "Nice."

Robbie Valentino = Zombie 

Robbie "An undead. Creepy, but cool."

Pacifica Northwest = Gorgon (What Medusa is) 

Pacifica "A snake lady! ugh, I can't stand snakes."

Shinshinjane "You know there's a few versions of you being a unicorn centaur or an angel."

Pacifica "I'll take what I can get."

Gideon Gleeful = Vampire

 Gideon "Whoo-wee! I must be charming."

Mabel "No you must be not."

Bill Cipher = Human Hunter

Bill "Man into monsters, monsters into man. Makes sense."

Fiddleford McGucket = Scarecrow

McGucket "I did get ma hat from a scarecrow."

Candy Chu = Kappa

Grenda Grendinator = Meroctopus

Mable "Even my friends are water monsters. At least I think Candy's a water creature."

Shinshinjane "The Kappa is an ancient creature in Japanese folk tales. They say that the Kappa will drag foolish children into the waters and drown them."

The kids took big gulps in fright of the Kappa's description. But then Mabel remember something earlier.

Mabel "Wait, Stanley?" turns to her Gruncle Stan "But your name is Stanford."

Ford "Wait, you took my name? What have you been doing all these years, you knucklehead?!"

Dipper "Yeah Gruncle Stan, what's with all of the secrets you've been hiding all this time?"

Mabel "And what happened between you and your brother?"

Wendy "Yeah man, tell us."

Gideon "What's the true secret about the journals?"

Pacifica "If you don't tell I'll sue you."

Robbie "This weirdness has to stop."

Soos "And this better be a line to my fanfic Stan, otherwise I will be very disappointed."

Bill "I'm just here for the heck of it."

Stan sighed "Alright alright, settle down and I'll tell you. It all started along time ago in Glass Shards New Jersey..."