The Forgotten Demon {Gravity Falls AU}

Prologue

Mason always had nightmares.

They were always pretty similar, too. At least with some things. Always a few consistencies.

First, he was falling. And when he landed, there was an eye. One, massive eye in front of him. A voice shook the empty world around him with words he couldn't understand. Sometimes he did, and they felt familiar. But he'd always panic and start running away. The words would chase him, and eventually, he'd stumble and fall. He still kept trying to run, though. Every time. And every time, there would be a wall. It'd get closer, like invisible barricades were closing in on him, trying to choke him out, before he'd shout defiance. A blue light would encase him, blazing hot, and he managed to get a glimpse of flames.

Mason's eyes shot open. He tried to catch his breath, shaking as he stared at the dark ceiling of his room. He scanned it, before slowly and cautiously turning his head to see his sister. He let out a sigh of relief and tried to relax as he shut the sight of his room off from himself again. He hated those nightmares. He woke up burning, and with a pounding headache rocketing around inside him every time. You could've thought he'd be used to them by now, that they wouldn't have such a profound effect on him. But they still did. And if it wasn't a nightmare, it was a dream. A few different kinds. Sometimes he was friends with the eye. Others it was simply watching him from afar as the blue, erupting heat blazed around him at his will. There was a couple where they simply sat in silence, staring up at the inky black that surrounded them, decorated and dotted with faint glows.

It had gotten even worse at the start of the summer. Mason's parents had decided that he and his twin sister, Mabel, needed to get outside more. So they were sent down to Oregon to stay with their great-uncle Stanford in a small town called Gravity Falls. Predictably, his twin had taken to a more positive outlook on their living arrangements, out in the middle of nowhere. Mason, though, didn't like the situation all too much. There were bugs everywhere, and the forest was creepy. He always felt like he was being watched. His mosquito bites from just yesterday had spelled out "beware." Not to mention he barely got any sleep at all now. It was tolerable before, and he could manage to fall back asleep, but ever since he got there Mason couldn't even try without feeling like something was staring him down. Watching and waiting for him to drift off.

Mabel said he was paranoid.

Stanford said he was "pining" for attention.

Wonderful wordplay, Grunkle.

He gave a quiet sigh and drowsily sat up as he opened his eyes again. Maybe they were right. He was probably just being paranoid. He stumbled to the door after changing, careful not to make too much noise, using the moonlight from the window to guide him. He wandered down the steps, keeping his hand on the wall to help him down to the ground floor. Some fresh air might help. He always liked walking around for a bit when he couldn't take much more of his nightmares. They were short trips, of course, if he even went anywhere, but they helped clear his head. Sometimes he'd simply sit outside the door of his house back in California. He put a hand into his jacket pocket, opening the door and stepping out onto the porch of the Mystery Shack, and staring out into the forest. It was a bit chilly, but that was expected this late. He shut the door, putting his uncovered hand into his free pocket, and started to head out. Mason watched the lining trees around him, then the sky, splattered with shining stars and patched with trees blocking the inky blue-black. It was lit by silver, the clouds gleaming gently from the silently dripping moonlight. He took a breath and returned his gaze ahead of him. He needed this, everything felt clearer already, and the slight gnaw of the nighttime breeze helped him cool down. He glanced at his shadow, angled slightly to the side of his view like it was walking just ahead of him. He slowed his pace, watching it pass over the tree roots and soil, and take its hat off as he did and fiddle with it. He averted his gaze to the cap, adjusting the strap on the back before putting it back on. It was too tight. Mason stole a glance back at his shadow again, vanishing as darkness flooded over it. He looked at the sky at that, just to see the clouds drift over the moon, and he halted. Shifting where he was, he looked around at the forest, then behind him, before rounding himself around and starting to walk back to the shack. He didn't want to get lost.

"Mason," Someone spoke, and he stopped short, mid-step. He felt himself tense and looked around the trees, unnerved. It was silent again, aside from the wind, but the voice had felt like it was the wind. Directionless, though, his fists clenched in his vest as he took a few steps backward, facing the way he had been going once more. "Hello?" He whispered out. "Who's there?"

He got no response, of course. It sounded familiar. And then it repeated, louder, longer.

"Mason," The voice started vaguely. "Come find me." It then dared him.

He hurried his steps back, before turning on his heel and starting to run, shaking a little again. His thoughts ran with him, trying to figure out some solution or explanation that would make sense. Maybe it was just a new nightmare. He had other dreams occasionally, this could be one of them.

He stumbled a couple of times as the Mystery Shack came into view, what he could only assume was the lack of sleep starting to pin him down as he slowed, and struggled to keep his eyes open. He was spending energy he didn't have, or trying to. He made it up the porch, barely, shutting the door once he entered in a half-awake manner and stumbling back up the steps, once again met with a decorated void of a sky seconds after he fell back into his bed.