Gravity Falls, three days after Weirdmageddon. Mabel and Dipper are back in Gravity Falls to relax and unwind. Finally without that yellow triangle, or so they thought.

Mabel: Hey, I'll just unpack and you can go check on your Wendy~

Dipper: Mabel, I've told you a thousand times that I don't like her anymore! Mabel rolled her eyes at her brother's excuses and sat down to unpack her suitcase. Mabel: Yeah, yeah, right. In the four years I've seen you, you've been following her around and asking her out-.. Dipper interrupted Mabel. Cutting her off at the end Dipper: Okay, okay, think whatever you want. I'm going. Dipper left the Shack and went to Wendy's house, surprisingly she wasn't there. After that, he decided to head into the forest, what if she was there?

He walked into the forest, it was the same as he remembered. Beautiful and filled with all sorts of strange creatures, fifteen minutes later Dipper didn't even notice how he reached the statue of Bill, too immersed in his thoughts. He tripped Dipper: Ow, Wh-.. Before he could fall, he felt a hand on his waist that pulled him to itself and didn't let him fall, Dipper was happy but also surprised. Maybe it was Wendy? He thought so. Dipper: Hey, Wendy, I was just looking for you-.. But when he looked up, he noticed that it wasn't Wendy, and not even Mabel. It was the real Bill Cipher, who was just looking at him, almost studying him. Dipper: Bill, what the-.. Before he could finish speaking, he was pressed against a tree and sniffed carefully. Why the hell was this demon acting like that? Yeah, he's a bastard. But not that bad.
Dipper tried to push away the vile demon that was clinging to him, but the arms closed around him. And suddenly, Dipper felt a strange smell from him. It was alpha pheromones, wait... Was he in a rut?!