This is about Reverse Falls. Reverse Falls is made by fans of Gravity Falls. Also, the reversed version of the characters of Gravity Falls. The four main characters of Gravity Falls with the name of their name in Reverse Falls:
Dipper Pines - Dipper Gleeful, Mabel Pines - Mabel Gleeful, Gideon Gleeful - Gideon Pines, Pacifica Northwest - Pacifica Southeast