A/N: Welcome, to my second ever Gravity Falls fanfic! this was an RP (roleplay), a collaboration between me and a friend of mine (Ace). I hope we got the characters spot on. We really had fun doing this, and I scared myself even.

Roles:

Dipper: Ace
Bill Cipher and Mabel: Me

Darkening Souls
Prologue

It was another late night. Dipper was sneaking out the window. He always woke up his sister, either by slamming the window behind him too loudly or leaving it open and letting the cold air in. This night, he had on a backpack that made loud clinking noises as he moved to go out the window. He wasn't even halfway when his sister woke up.

"Dipper...?" his sister yawned, her eyes opening halfway, "where are you going this time...?"

He stopped in his tracks, pursing his lips. He still had his eyes on that window, "This is my last trip, I promise, Mabel. I just, uh, have to... I have to do some things." He spared a quick glance at her.

Mabel frowned slightly, but she's much too sleepy to argue, "Mmph.. alright... I guess I'll see ya later, bro-bro?"

"Yes... later..." he sighed, "I'll see you, but you won't see me..." and then he opened the window.

His sister had almost fallen back asleep, but this alarmed her, "Won't see you? really? seriously, what's the problem here?" She woke up a little more, her eyes narrowed.

This opened the floodgates. Dipper sighed, "Mabel, every night since that failed Sock Opera, Bill's appeared in my dreams. Turning them into nightmares. Nightmares where I hurt you and Stan and everyone else I care about. He says that they'll come true..." he paused a while, as if waiting for his sister to say something, but then continued, deep worry in his eyes as he turned to face her, "Mabel, I'm terrified. I can't sleep, not now, not ever, not like this! I just... I can't!"

The bags under his eyes were dense. He had hardly slept for the past few nights, and that must have only built his paranoia. Mabel sighed.

"You realized that if you try to avoid the problem you'll only force it to happen... right...?" she muttered slightly.

Dipper frowned. His sister didn't seem to understand, and so he explained it more, "Mabel... I hurt you. I stabbed you, over, and over, and over, until you weren't bleeding anymore, until you weren't breathing anymore. And I didn't stop, even after that." Tears were running down his face. He was honestly terrified, evident by his wide pitiful eyes. "I can't hurt you for real. I can't lose you again," he opened his book-bag, revealing it was full of knives and forks. "I'm getting rid of these... so I don't hurt you... ever again..."

Mabel then woke up completely, and hopped up out of bed, "We use those to cook, ya know..." and then she took a deep breath and sighed, trying to think of a good way to explain and calm her brother down... "Now, listen... the only way Bill will enter your mind and take over is if you make a deal with him... you have nothing to fear..."

"I just want the nightmares to stop..." it didn't seem like he heard her, "I just want it to be over..." and he dropped the bag, and it clashed against the floor, some of the knives and forks falling out, but he hardly noticed this.

Mabel crossed the floor and hugged him tightly, "I'm here for you, bro-bro... you'll be okay... Bill won't be coming for you.. and, if he does, we can always beat him... together."

He smiled softly, returning the hug. Her comfort seemed to be working. He then looked into her eyes, "You think we could cuddle... tonight? I can't sleep alone..." he took a deep breath and closed the window.

"Sure thing, Dip-Dop!" she giggled, her everlasting optimism shining through as it always did.

Dipper laughed playfully, "I think we need to make some dream catchers or something. Keep Bill out."

Mabel slowly gained the biggest grin ever, "Yeah! we should do that! I've got the materials right here!" and then she pulled out of hammerspace all the materials they needed to make a dream catcher.

Her brother, wide-eyed, stared at these materials. He then yawned loudly, "Uh, not right now. It's late, I need my sleep, yata yata yata... let's just sit and cuddle until we fall asleep."

"Alright then..." she smiled, putting the materials away and heading back to bed. She sat and then patted the empty space next to her. He walked over, sat down beside her, and lay down.

"G'night, Mabel."

"G'night, bro-bro..." she also lay down, smiling brightly, and eventually fell asleep. Dipper embraced her, and drifted off into sleep, fearing the nightmares he was certain would come.

But they never did. In fact, it seemed a bit too peaceful... except for the ominous triangle floating near the foot of their bed, a monstrous grin on his eye. So, for the first time in two weeks, Dipper had pleasant, gentle dreams. He smiled softly.

Maybe Mabel was right.. I'm worrying for nothing...

And then a voice he thought he'd never hear again rang through his head, I wouldn't say that so soon, Pine-Tree... and then it cackled.

Dipper's eyes opened wide as he heard Bill. He looked around, confused. He could see little from his intertwined state with Mabel, and didn't want to move.

It's late. My mind is playing tricks on me. I'm fine, he told himself again, but this time, was unable to rest.

Bill chuckled, happy that he was at unease. He stayed silent for a while, making him think it was only a figment of his imagination. Toying with Dipper amused him so much.

The boy eventually went back to an uneasy sleep, hoping it was not real, hoping that he had seen the last of Bill...

The demon chuckled again, his hands clasped. Dipper'd have nightmares again, no matter what. He was only here to toy with him, and hopefully to gain something more. And, boy, was it fun.

The preteen, this time, scrambled out of bed and stood up, having managed to get out of the intertwined state.

"Hello?" he looked around, startled.

"Oh, Pine-Tree... I thought you'd never wake back up... though that would have been absolutely fine with me."

"Stop messing with me! what do you want from me, Bill?" he was pleading. Exhausted, it was hard for him not to show his feelings.

The triangle grinned, "Only to mess with ya. Heheh... you're pretty funny when you're suffering." He floated upwards, raising his hands and laughing slightly, "It's like watching a comedy!"

Dipper stiffened, "Just leave me and my family alone, you evil triangle! we've never done anything to you!"

"Heh! like that even matters!" and then he suddenly disappeared.

The boy looked around, fearful. His experiences taught him that an enemy unseen was worse than one in plain sight. Bill popped up again, behind him and upside-down, "Boo!"

He laughed as Dipper screamed, "Cut that out!"

"Nope! it's hilarious seeing you suffer. Particularly with those nightmares I send you every night," he then floated in front of Dipper, turning himself right-side-up. "And you can forget what Mabel told you... I'm always there... and your nightmares will come true."

"I don't believe you!" Dipper spat.

Bill scoffed, "You'd rather believe some meat-sack than an all-powerful demon with precognition?"

"You've lied to me before. You wouldn't hesitate to do it again."

"Well, I'm flattered that you know me so well! but, let's say that I wasn't lying..." and suddenly a knife appeared in Dipper's hand.

Dipper tried to drop it, but, to his dismay, found that he couldn't. He freaked out, "No, no, you won't make it be real!"

Bill only grinned monstrously, "Really now?" and raised a hand, controlling the nerves in Dipper's arm.

The kid was terrified. He knew what was coming. "No! please! don't do this!" His eyes were beginning to water as his arm mimicked Bill's.

"You really think I'll listen to you?" the demon let loose a frightening cackle, "you're awfully mistaken, Pine-Tree! and here I thought you were smart!" and then he swung his arm to his left, towards Mabel.

"I... no..." he fought the impulse the best he could, "please! don't hurt her! MABEL! WAKE UP! RUN!" he screamed, terrified.

Mabel was, unfortunately, in her deep cycle, and couldn't hear a thing. The knife barely missed her, suggesting that Bill was still toying with Dipper. He chuckled, "Heheh, this is fun! seeing you all terrified like that!"

"I'll give you anything. Just leave her alone. Just spare her, and take me!" he pleaded once more, tears running down his cheeks.

"Anything, you say?" the isosceles monster grinned, bringing his hand down to his side, which made Dipper's do the same.

Dipper took a deep breath, "Anything. She's my twin sister. I'd do anything for her." He looked up, his cheeks wet.

Bill then got uncomfortably close, "Then you owe me another puppet..."

"W-what?" he looked at him, confused and upset. The fact that Bill was practically in his face didn't bother him for some reason.

"You know..." he pointed at Dipper, overbearing grin on his eye.

Dipper glanced at Mabel, not noticing the finger pointed at him, "You don't mean..."

The demon was slowly getting frustrated, but his grin got larger in turn, "No, not her... though thanks for the offer!"

"Then what do you want? you already have my body, don't you?" he raised an eyebrow.

The golden triangle hummed with pretend thought, and Dipper waited, not moving a muscle.

"Hmm... how about your soul then...?"

"What does that mean?"

"Give up your soul, kid.." his eye narrowed, frustration starting to show. The fact that the kid was sleep-deprived for several days on end and that this could have interfered with how he usually thought didn't matter to Bill.

"How do I even do that?" it was clear Dipper wasn't thinking.

"Just shake my hand..." he grinned, and outstretched his hand for his.

Dipper hesitated for a second, but took Bill's hand. "Deal," he exhaled, startled. The demon's blue fire spread throughout his arm, and Dipper began to feel something very wrong...

He shrieked internally, seeing the turquoise flames travel, and started feeling something being wrenched from himself, and that grin was still on Bill's face as he began chuckling.

Dipper's mind was racing, What's happening to me? WHAT'S GOING ON?! his terror was clear.

The triangle's chuckles rose into monstrous laughter, as something—a sphere—transitioning from light blue to dark blue and back again began to emerge from his chest. Dipper looked down at it, What is this? what have I done? panic making his eyes wide and pupils tiny.

The laughter soon died out, and Bill stayed grinning at the boy, "I'm surprised you don't know your own soul, kid... well, no matter... it's mine now..."

"W-what do you mean?" he was terrified, "what have you done?" the second question was directed more towards himself.

"You said anything, kid..." Bill let go of his hand and took the soul, grinning as he pondered whether to succumb to his hunger and devour it or to hang it over Dipper's head permanently. He decided that the second option would be much more amusing.

Dipper tried to grab it, "Why did you even do that?"

"You said I could have anything. Remember?" Bill reiterated, holding it away from him.

"Yeah, but why that, of all things?" the preteen still tried to get at it, but to no avail, for the triangle floated out of Dipper's reach.

"You'll see..."

"Wait," Dipper realized something, "wait, wait. I just literally sold my soul to a demon, didn't I?" he then facepalmed.

Bill cackled even more, kicking his legs, "I'm surprised you even did it! boy, when you humans are desperate... well, I don't even need to say it!" and cradled his soul closer to himself, ignoring the pangs of hunger.

"What are you gonna do with it?" Dipper gasped. "Is it gonna be like that anime where souls get eaten?"

"Actually, no... as much as I'd love to..." he snapped his fingers, and a jar materialized around the soul, "I've got another use for it..."

"And that is...?" Dipper was getting bored, surprisingly. The exhaustion was really kicking in, now that the adrenaline was leaving his system.

"Like I'd ever tell you!" the demon chuckled again, and the jar then vanished.

"It's my soul! I'd like to know what you're doing with it!"

Bill only grinned, and then Mabel began to shift, moaning slightly. He noticed this, and his smirk got even wider, "Heh, looks like I'm saved by the star! I'll catch ya later, Pine-Tree! hahahaha!" and then he vanished, just when Mabel slightly opened her eyes.

Dipper groaned, noticing light coming from the window. He dropped the knife that he hadn't realized he was holding, and fell to the floor, unconscious.

In the meantime, Bill was in his own dreamscape, clutching Dipper's soul jar to himself. He couldn't believe he had actually done it. He got a soul, and the kid's soul no less! now to enact his plan...

A/N: Whew... what a dark turn it took, and it took it so darn QUICKLY. I hope you enjoyed, and I'll see you this Saturday or next week with another chapter.