That One Thing We Knew

Dipper didn't mean to contribute to the destruction the Companion was about to cause. But he had been there. It was his hand that ruined everything, wasn't it? And now all of the Imaginarium was doomed. [Heavily crossed over between Gravity Falls and Invader Zim, hints of other Universes. Multiverse AU thing? You'll learn stuff as you go. Lots 'O OCs.]