It was a hot summer in Gravity Falls. You were the sister/brother of Dipper and Mabel, but you usually preferred walking alone in the woods. And then one of these days, when you are walking through the forest, when you sit down to rest by a tree, a stranger with a head in the form of a pyramid appears on a large branch, he looks at you with his only eye, as if grinning at it

"So, so... who wandered into the depths of the forest. You probably need help."