UnderFalls Tale

This is an au of Gravity Falls and Undertale. At the start of their 2nd summer at the Mystery Shack, Mabel and Dipper fall into "The Bottomless Pit", also once known as the top of the long forgotten Mt. Ebott. I don't know if this is an existing au, but it sounds fun, so I'm just going to start writing and hopefully I'll get something Awesome from this idea. If anyone had this idea before me, please let me know so I can put your name in the disclaimer, speaking of which: DISCLAIMER: I don't own Gravity Falls or Undertale, I just came up with this idea for fun. I love the show and Video Game, so this is based around both of the characters and places. Also this is apparently a thing called Gravitytale Falls. I did not make that up, and I may not have spelled that correctly. Anyway have a nice time reading.