The Beginning of the End [ Gravity Falls + Phineas & Ferb + Doctor Who ]

The Meeting

The Fletcher brothers and their friends walked and walked and suddenly saw a shack. They went in and look around for a while.
Stan went back to the Mystery Shack and saw the children there. At first he thought they're stealing things, but then he saw their were waiting for something, so he went are asked «Who are you! What are you doing in my house!» The kids told him about the portal and every single detail. Suddenly Stan got an idea. He knew that those kids could help with his portal. They accepted and start building things. After hours they finished the machine and turn it on.
«It'll delay a pair of hours» said Stan.
Dipper, Mabel, Soos and Wendy arrived to the house. When they saw the kids, they didn't understand what was going on. So Dipper asked «What's going on here! Who are they! What's that things that seems be a portal into different dimensions!» Stan didn't want to tell them, but he owed an explication. «Look kids... I didn't want to tell you these, because I thought you couldn't understand. But now is the moment. ......I'm trying to remake the portal to bring someone back.»
«I don't trust a word» said Dipper.
«How can we know that the story is true? You're always making up stories» add Mabel.
«Kids you have to trust me. Look... I know that I'm not the kind of man who is nice to everyone or make something for others, but please... you have to trust me» replied Stan.
«No Mabel, shut it down! It's a trick, it's always a trick.» said Dipper.
«Mabel please.» begged Stan.
«I'm sorry Dipper. I trust him.» answered Mabel.
And suddenly they could see a human shadow appear in the middle of the white, and blinding portal's light.