About the AUEdit
Spawning from fanart, this AU places the Big Four, and other such characters in the fandom, as characters from Gravity Falls.
Given his bookish and painfully curious way of thinking beyond the parameters of those around him, Hiccup is usually portrayed as surrogate to Dipper Pines. The Dragon Manual or a book version of the Dragon Eye can serve as Journal #3.
Given Jack's natural connection to the supernatural, he is usually portrayed as himself.