Okay so you guys have been asking for a Demented sequel and I have thought about it and maybe just maybe there will be a sequel. This isn't a sequel, just another GF fanfic by meh! So here's a longer summary:

   We all know that Dipper likes Wendy, but age always drives them apart. I've seen many things where Dipper gets older and he and Wendy are the same age. Well Dipper's been shown older, so why not make it to where Wendy is younger? Will they have a chance? When Mabel finds a strange device that turns any human younger when zapped, things get crazy.

  Now it's up to Dipper and Mabel to try to turn their pals back to their correct age. Will Dipper want to? The twins, and their 12 year old uncle, Wendy, and Soos go through the portal the strange device came from sending them all to a Reverse like Gravity Falls. There they need to go on the search for the cure while getting into mysteries. Including a run in with Bill Cipher the human who also happens to be looking for the same thing.

Updated Author Note: 

I wrote this circa 2015 so there are a loT of grammar  mistakes I've seen, also I totally misspelled Grunkle. Hopefully I'll get to edit it up a bit soon!