A/N: So, this is my second Gravity Falls story, and it's based off of an AU that I made. So basically, in this AU, Bill and Will Cipher originally started as humans and became demons through reasons you will find out later. Also, in this AU, DMvtF and on doesn't happen, so yeah.

On with the story!

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Gravity Falls was always a weird place, even before it was called 'Gravity Falls.' It had a big forest, full of dangerous, mysterious, gentle, and goofy monsters alike. But it wasn't just monsters who lived in that forest.

In a small clearing in the woods, there is a little cottage which houses a family of four. Two twin boys, one a blonde, one a bluenette, live with their mother. Their father had left when the two boys were but six on a fishing trip, and has yet to return.

The boys lived happily in spite of this, and interacted with the monsters in the forest as they would a friend among their many adventures. But they're going to go on one adventure that will never end...

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The sun is shining. Birds were chirping. Monsters were roaming about. This was what young William Ceaser Cipher woke up to that bright summer day. He rubbed the sleep out of his azure eyes and shook out his bright cerulean hair. He looked over to the other bed to see his still sleeping brother, William Atbash Cipher. His amber eyes were closed, and his blonde fringe moved as he breathed in and out.

Will sat up and pushed back his blanket. He was ready for one of his brother's weird adventures. He hopped out of his bed and walked over to his brother's.

"Bill?" No response.

"Bill." Still nothing.

"Bill!" Will shook him a little this time. The blonde just rolled over.

The bluenette groaned. Bill was really asleep. And he wasn't waking up anytime soon.

Will straightened up. Well, that was just fine and dandy. He'd just have to start the adventure himself.

He left the room that he and Bill shared, and walked out into the main room, where his mom was already up and about.

"Oh, good morning, William," she said, smiling as he walked in, referring to him by his full first name.

Will smiled back, albeit more shyly than she. "Hello, Mum," he said back. He pulled one of the chairs out from the table and sat down across from her.

"So..." she started, dragging out the word. Will looked up at her. He noted how much Bill took after her. Same speaking mannerisms, same relaxed posture, same skinny structure. The only difference was that she had pale skin, something which Will himself took after.

"Yes?" he answered tentatively.

"Where is your brother?" she asked, looking behind him as if hoping to see the blonde appear.

Will sighed. "He's still asleep," he replied, scowling.

His mum laughed. "He is a very heavy sleeper," she said, once she had settled down. "He gets it from his father, that's for sure."

Will perked up at the mention of his father. "Um, speaking of..." he started hesitantly. Sharp amber eyes turned his way, and Will had to fight the urge to look away. That was another thing that she and Bill had in common: sharp, all-seeing amber orbs that could make you feel uncomfortable with a single glance. It made their glares all the more scary.

"Yes, William?" She looked at him with concern, which made Will hope that the answer to his question was a happy one. He would hate to have made his mum cry. One look at those tearful amber eyes and his dam would burst.

Taking a deep breath, he continued. "Have they found Dad yet?" he inquired timidly.

The look of concern quickly turned to surprise, which then turned to a sort of angry sadness. "No, they have not," she said stiffly. "I'm sorry, William."

Will almost gave a sigh of relief. Yeah, he was sad that his dad was still missing out at sea, but his happiness at the fact that he didn't make his mum cry was overwhelming.

"It's ok, Mum," he said. "Besides, I'm kind of used to it." And this was true:

His mum gave him an odd look, before saying, "Why don't you go outside, William?"

"By myself?" That idea alone was scary. He and Bill were almost never separated. Bad things happened whenever they got separated.

His mum waved a dismissive hand. "I'll send Bill after you when he wakes up," she told him, albeit very distractedly.

"O-okay, if you're s-s-sure," Will complied, rising from the table and walking the short distance to and out of the door.

As soon as his bare feet hit the grass, all thoughts of worry melted away. The sun shone down on the forest floor, illuminating all of its colors. Woodland creatures were roaming about in the forest. In the distance, Will could hear manotaurs stomping and gremloblins roaring.

Or were the gremloblins stomping and the manotaurs roaring? Oh well, they did both anyway.

Will stood just in front of the door, wondering what he would do while Bill was still sleeping. Adventuring was definitely out. They only adventured together, a rule that the two had made up after an adventure that had gone horribly wrong.

So what else could he do? The manotaurs were loud and obnoxious, the gnomes were dumb, the gremloblins were big and scary...

Then it hit him. Multibear! He could go and have tea with the Multibear. She was really nice to him and Bill, especially when she had found them wandering around aimlessly in the forest when they were but four. Ah, yes. He remembered that day like it was yesterday...

They had been battered and bruised, and tired. He had been sure they were lost, but Bill had assured him in a loud voice that he knew exactly where they were. Will had tried to quiet him down, saying that if he was that loud, he might attract a monster. Unfortunately, he had done just that. The Multibear had lumbered out of the forest, holding a large branch that had obviously been ripped off of a tree. Her eyes had latched onto the boys, who had been too scared to scream.

"Are you lost?" she had asked. When they hadn't answered, she had continued, saying, "Come with me. I'll help you."

The two had weighed the options in their heads, and, seeing as they didn't know their way home, had decided to go with her after acknowledging the simple fact that she hadn't mauled them yet.

Bill and Will had stayed in the Multibear's cottage-sized cave for at least three days until their dad had found them playing outside while she watched. He had approached quickly, yelling their names.

"Bill! Will! There you two are! Your mom and I have been searching the whole woods for you!"

The two boys got up to run towards him, but Multibear, not noticing their dad's scent, jumped in front of them, growling and baring her teeth. Their dad, who was unarmed at the time, got into a fighting stance and was about to advance when he stopped.

"...Multibear?"

This had made her calm down a bit. She raised her head tentatively, and looked at him with a curious expression. She opened her mouth to speak-

"Ack!"

Will looked up sharply from where his face fell in the dirt, wondering exactly what it was that had knocked him out of his thoughts. He really hoped it wasn't a gnome. Long story short, those encounters did not end well. He looked back nervously, and was relieved to find that he had tripped over a rock. A very weirdly positioned rock, now that he looked at it again.

Will walked back over to the rock, studying it carefully. The rock was big and weirdly shaped, what with its two carved circles and carved line, and the way it stuck out in the middle of that. 

"Huh, this rock looks like it has a face," Will said, chuckling quietly. "Bill would love to see this." The bluenette bent down to start rolling the rock toward the cottage, his previous quest forgotten.

However, as he was rolling the rock away from its spot, the grass that the rock had been resting on gave, and Will's foot fell through.

The bluenette let out another yelp as he scrambled to get out of the trap he found himself in. Once he did, dirt fell into the hole, covering something. Something shiny.

Will let go of the rock and began digging dirt out of the hole. He kept digging until his hand hit something. Slowly, he pulled out a thick leather book coated in dust and dirt. Quickly brushing it off, Will gasped at what he saw.

The book had a glimmering cover that was christened with the words, 'The Book of Demons.'
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Oh, my God! I'm finally finished with this first chapter! It was so hard to write!

So, I hope you all like it! As y'all know, I worked very hard on this. Anyway...

REALITY IS AN ILLUSION, THE UNIVERSE IS A HOLOGRAM, BUY GOLD, BYE!!!!