Tags: She mostly writes stories centered around Mabel and Dipper's brother-sister relationship, and she is fantastic with her descriptions of how the characters feel and keeping them in character at all times. Honestly, if you're looking for someone who can write a truly heartfelt fanfic, look no further than Mayclore.
Tags: He's written quite a few Gravity Falls fanfictions, but my favorite one is "What Do Angels Look Like," which focuses on a young girl named Avy who Dipper finds and takes in after finding out her father abused her. It's one of the most emotional and heartwarming fics I've read, and I think it deserves more attention. When you're done with that, another fic I'd recommend is "Dipper and Mabel Jr," though it hasn't been conpleted yet. He's also written a few Pinecest stories, but I'm willing to forgive him for that.
Tags: Has written almost 40 Gravity Falls stories, mostly one-shots, but also the multi-chapter "Little Shack of Horrors", a Little Shop of Horrors parody. Many of the stories are humor, but the author also expands into horror, hurt/comfort, family, and angst, among others. Does an excellent job writing Dipper and Mabel's sibling relationship.
Synopsis: Mabel Pines' signature, heat-trapping fashion statement has a sensitive origin. When that nerve gets struck in an argument with Dipper, she ends up reminding herself of the things that are truly important to her.
Comments: A skillfully written and engaging one-shot that manages to include dark, yet subtle psychological elements while still maintaining the lighthearted narrative of Gravity Falls. Mabel is written very well. A very heartfelt story.
Synopsis: After 2 years, 2 summers, Dipper and Mabel Pines have returned to Gravity Falls. When Dipper meets a new girl, could she be the love of his life, or just another pretty face? Created by the same person who created the Gravity Falls fanfiction wiki, this is her first Gravity Falls fanfic.
Pairing(s): DipperxOC, MabelxOC
Tags: Both Dipper and Mabel are paired with OCs. Het.
Synopsis: The town abandoned and left to fall to ruin, subject of many a horror story. Wendy returns to Gravity Falls, in order to pay respects to those long since passed.
Comments: This is, in my opinion, the best Gravity Falls fanfiction to date. Horror/Angst, and it works both extremely well while staying in the realm of plausibility (well, as plausible as a paranormal show can get).
Synopsis: Some day Stan will have to tell the twins the truth and change their world forever. A one-shot look into what could be Stan's motivation through the first few episodes.
Comments: Though it seems to come out of left field, the theory presented (that the twins' parents died 2 years before the show and the twins unconsciously used their innate magical gifts as Pines to keep them "alive" because they couldn't imagine life without them) makes a surprising amount of sense and makes Stan a surprisingly sympathetic character. In fact, I wouldn't mind if something like this was canon.
Synopsis: On his 13th Birthday, Dipper Pines receives a gift that he had always hoped for. However, an old enemy uses this to gain an advantage, and shortly, Dipper is launched into an unexpected adventure.
Comments: Fantasy/Parody. A very well-written tale of a game jumping adventure that would make Wreck-It Ralph proud. Features parodies of several well-known video game series.