He's faking it, Sans. (Undertale x Gravity Falls Crossover)

Chapter 7

Papyrus, though he wasn't one for violence, was actually contemplating if he should slap Mabel or not. Of course he didn't, but the thought of violence to deal with his emotions did flash throughout his mind.

He was having a lovely honeymoon with Mettaton, then, on the last day, the sky suddenly turned red. He drove home with his husband in a hurry to discover a few citizens turned to stone and his brother unresponsive over text. Then after finding his friends at Alphys' lab, Papyrus learned some more facts that had him upset.

"So you're saying this after this all happened before, and you found out the demon who did it was still alive and dating my brother, and you decided to not tell him?" Papyrus demanded.

"Bill wasn't doing anything, I thought it was safe! I thought I was... Sans was..." Mabel blinked back tears, dogging into her brown hair. "I didn't mean to! Bill wasn't doing anything, he said he just wanted to be with Sans. And it was like all of those romantic movies where love wins so -"

"Mabel, I thought we learned this last year!" Dipper yelled, "Your love quests got us almost killed several times! And you know Bill is a manipulative demon! Sans was an old scientist, of course Bill would try to date him, to get the equation!"

"I know!" Mabel replied, trying not to cry.

"Hey, I don't think yelling at her is going to fix anything. It's pretty clear that we have a doomsday kind of situation on our hands." Undyne placed herself between them, to focus on the important part. "You guys have all dealt with this before, but we know from Papyrus this isn't just inside of Gravity Falls. We might all be surviving because of the weirdness runes you guys placed in all of the public buildings, but the rest of the world has no idea what's going on."

Dipper nodded, she was right. Gravity Falls was the town most prepped for something like this. So far, from what Papyrus had told him, only four of the towns citizens were turned into statues. That was it. They were just the four who were unlucky enough to be caught right when it happened, but everyone else had time to prepare. The rest of the country, or even the world, didn't.

"So he dated my brother just to get the equation. That was it? Sans was... just for that?" Papyrus clung to his scarf, frowning at the idea of Sans being used. He'd be dealing with Bill personally for sure.

"I thought Bill liked him! He talked about him so sweetly and even looked happy!" Mabel covered her face, "I'm so stupid."

"It makes sense, though. Bill used the soulmate dream to trick Sans, then built a body and personality Sans would be most attracted to and trick him into giving the equation. No wonder it felt like they were soulmates, Bill literally made himself for Sans..." Dipper tapped the birthmark on his forehead. "What did he do with Sans, though? After he used our Grunkles he just sorta left them."

"Do you think he put him into a bubble, like mine?" Mabel asked.

"A what?" Undyne asked.

"A bubble. My sister was trapped in this perfect world so she'd never leave. He might have done that to Sans. He did it to Mabel to keep her from teaming up with me, since he knew we could have a chance to stop him."

"Could we try the magic circle again?" Wendy finally spoke up from her spot in the window, lowering her crossbow as she turned towards the others. "It only failed last time because your Grunkles got into a bad mood. But this time everyone is on good terms."

"Our Grunkles aren't here, though," Mabel groaned lightly.

"And the magic circle is a spell we tried to use to kill Bill before. It didn't work." Dipper was quick to explain to the others, holding out his hand. "We need certain people to stand in a circle and... it's better if you guys just saw it in action."