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

Chapter 1

"Ah."

Bill outstretched his hand, looking through the transparent material in the darkness. Pathetic, really. He's waited a whole year after being recovered, feeling rather miniscule over his ending. How embarrassing. Him, a dream demon, defeated by a small memory gun of all things.

At least the humans were just as pathetic as he was. They were so entranced in losing their beloved Stan that they forgot that bringing him back would, in turn, bring back Bill. He quickly detached himself from the mind of the worthless old man, now hovering in the spaces between reality. The dimensional crack was still there, but his form was so weakened that he couldn't dare to risk taking over a town. His demon friends also were defeated, so at least he wasn't alone in a shameful appearance. They'd return, soon.

His powers were almost entirely back, but he'd need a new plan. All of the citizens were known to his tricks and plans, he couldn't just strike a deal with any of them. And sure, he could leave through the rift, but deals gave power, certainty. Without that stupid equation, nevertheless, he couldn't conquer anything but Gravity Falls. The old geezer that had that darn equation left, on an adventure with his brother. It would have been a relief to have them gone, they were major thorns in his side, but one of them held his only escape.

Dipper would never even dare to search for that equation, so that wasn't an option. Mabel was still in her boy phase, she was only 13, that wouldn't be over for awhile. Wendy herself was a clever teenager, but that came in quick brute force and fighting, not in meticulous equations. And that type of equation could only be found by an adult, he doubted any child could find it. It'd be best to build the rest of his strength before even revealing he was still alive.

Bill mindlessly swiped through images of the crack, exploring the town of Gravity Falls. Another world opened to it a few months back, he had noticed that before, but didn't really care. In fact, he was jealous. They were monsters, as he saw by the King, being a tall, broad goat man with a beard and horns. They were born with magic, though, not by the madness that demons were created from, effectively making them able to bypass the barrier. Annoying. Bill didn't pay attention to them, they served him no purpose. He saw they had a Royal Scientist, and he had been excited for a small period of time when they first escaped, but discovered she had no expertise in quantum physics. She was an engineer and biologist. Which, of course, only made Bill's return more difficult. It was hard to come by scientists as it was, or anyone even remotely smart enough to get to the levels of a scientist nowadays.

Stanford, within himself, was practically a blessing. Demons were creatures of power, not logic. Any science field always would fly over their heads, so Bill could never hope to even try and figure out an equation. And since he would forever be sealed to the small town of Gravity Falls, he couldn't go out and hunt down a scientist from a laboratory, he needed them to come to him. That was naturally a problem within itself, the town was desolate of any lures for scientists. The chances of one arriving, even within the next hundred years, was so small it'd be easier to just give up. Yet he persisted.

Maybe he could convince Dipper and Mabel to get the old geezer back before the heart attack age. The guy had another solid thirty years at the very least, that'd be plenty of time. All he'd have to do is plant some sort of problem that'd require a quantum physicist, get them to bring Sixer in person. Then Bill could exit, force him to make a deal with a hostage or something. That could work.

Now, where were they now?

He swiped his view again, narrowing in on the twins. Spending time with the monster scientist. What was her name? He called her glasses. Glasses was sitting with Shooting Star, eagerly discussing their favorite shows. Looks like they got along quite well. Bill would have to learn who liked who, but that was easily done.