Gravity Falls x MLP crossover!

Dipper and Mabel can't sleep one night, so they go take a walk in the woods. In the woods, they find a portal, and Mabel goes through it. Naturally, Dipper goes too. Hilarity ensues.

Takes place between Games Ponies Play and Magical Mystery Cure, and before Dreamscaperers. Set in Dipper's perspective. Additional tags will be added when relevant. If you think the rating should be changed or have ideas for the story, I'd love to hear it.