Laughter.
Way too loud.
It made Dippers head spin.
What he saw were all of his dark desires spilled out right in front of him, above him, and on the walls of his blank mind he had given him access to.
Him.
Bill Cipher.
The demon that had tried to end the world years ago.
The demon he had now let into his mind, willingly.

"Oh, Pine Tree, Pine Tree, Pine Tree! This is so much BETTER than I would have EVER IMAGINED!"
The last time Dipper had heard Bill laugh like this was when the rift had opened and the apocalypse had started in Gravity Falls.
Bill was floating above him in his usual triangular shape, and Dipper didn't dare to look at him, or at the pictures and scenes the demon pulled out of his own mind. He stared at the ground as if there was something incredibly interesting, but even like that he couldn't ignore what his own mind was showing him. All those dreams from the past weeks, months, years. Dirty little secrets he would never tell to anyone, wouldn't even write them down in a diary of some sort, wouldn't even admit them to himself.
"Y'know kid, my guess was that you wanted revenge on someone and didn't want to dirty your cute little hands. Summoning me to kill or torture someone, that's not uncommon among you meat sacks. But THIS? AHAHAHAHAHAAHA!"
Dipper felt his face heat up. His heart was throbbing so hard he was afraid Bill could hear it. The demon was laughing so loud that it almost hurt his ears.
"This is HILARIOUS!", the demon yelled, "I thought Sixer was weird about me, but boy, you're WORSE!"

Dipper kept his eyes closed. He knew what he was getting into. He didn't think twice about taking the deal, because he needed to find out if that really was what he wanted. He needed to see these pictures in his mind, needed to force himself to look at them, because he had locked them away for so long. He had been telling himself that this can not possibly be what he wants. No human would ever want something like this. But there he was, kneeling on the floor of his own dark mind, his entire body shaking because these desires were real, and they were his.

Bill had changed his shape. He came closer.
"Look what I just picked out of your messed up little dreams!", the demon said, grinning. An actual grin, because he now had a mouth. A human body, but not entirely human, as he still only had one eye, and where a second eye should have been was nothing but a black hole. He was taller than Dipper, had wild, golden hair and his fingernails were like claws. He wore tight, long pants, but no shirt. His skin was tanned and full of strange, thin tattoos, mysteries to be solved. His one eye was glowing bright yellow with the familiar cat-like slit that Dipper had stared into so many times, so many years ago. He was exactly what Dipper had imagined – or wished – him to be like.
Bill came closer.
"Naughty little Pine Tree. What is this? Have you been reading too many weird vampire romance novels? Watched too much monster porn? HAHAH. But I'm a man of my word, so you're going to get your end of the deal now", he said. His grin was way too wide to even look remotely human. It sent a shiver down Dippers spine and the young man started shaking again. He was scared, and thrilled.
"I've seen everything, Pine Tree. No wonder you haven't been in any relationship in all these years. You can't, right? Because when you ask yourself what you want, you think of this. You think of me."
The demon was so close now, so close, Dipper could just…

"Dipper Pines, you are truly messed up."
Slender fingers lifted Dippers chin. He stared into one eye, and one black void.
It was horrifying.
Weird.
Wrong.
Deadly.
It was exactly what Dipper wanted.
And he wanted to cry.
Why? Why did he want this? Why couldn't he just be a normal, decent human being?

Bill's lips collided with his own, and Dippers hands immediately moved to the demons chest because he needed something to hold on to. The demons kiss was hungry, possessive, so full of all the messed up emotions that have been boiling up deep inside of Dippers mind. And he kissed back. Opened his mouth in submission and let the other take every bit of control.
When Bill broke the kiss, Dipper looked horrified and turned on at the same time.
"It's adorable how even after I've seen all of this, some part of you still denies that these are your own and very real desires."
Bill grabbed his neck and slammed him into the ground. Dipper screamed at the pain, panting and trembling as Bill pinned him down. Blue Flames engulfed the young mans wrists and kept him in place. The pain wasn't real, because they were in the mindscape. But for Dipper, that was part of the thrill.
One more kiss.
Bill began to undress him.
It was almost too much already. Dipper was hard, and Bill once again broke into shrill, almost screeching laughter. Of course he would laugh, it was pathetic how turned on Dipper already was when Bill had hardly even touched him yet.
"I can give you so much more than this, Pine Tree."
Exactly what he wanted to hear.

An agonizing scream left Dipper's throat as Bill sunk his sharp teeth into his neck, drawing blood. He struggled in pain. The demon bit down one more time, the claws on his fingers ripping off Dippers last few pieces of clothing.
He was now naked, unable to move, and above him a horrible demon ready to do with him as he pleases.
The thought was not a bad one.
It made his blood boil.
It made him feel alive.
"Why…", Dipper whispered to himself in disbelief.
Bill let out a quiet laugh.
"Maybe you should've been born a demon. You don't seem too happy with your boring human self."
"I don't want this."
"You do. This was the deal. I'm giving you exactly", he paused and scratched his sharp nails all over Dippers chest and stomach, making him scream, "what you want."
Dipper knew that it was the truth. It was all over.
All this time of trying to convince himself that he was just an ordinary human… he wasn't.

Dipper Pines, you are truly, absolutely messed up.

Bills hands wandered all over his body, slowly and teasing, touching every bit of skin they could find. He used his mouth to bite and suck on Dippers neck every now and then. He managed to make him go crazy within very few minutes.
"Bill, please—"
"Please what?"
The demons eye seemed to glow even brighter now, it's colour changing to red for a moment, making Dipper stare at him in fear. Bill grinned again, very widely, showing off his razor sharp teeth. Oh god, Dipper was so turned on.
"You will tell me exactly what you want", he said, his fingers closing around Dippers throat, "now."
Dipper started shaking again, crying even, he struggled to breath and wanted to yank away the hand on his neck out of reflex, forgetting that his own hands were unable to move. And even so, he felt all of his fear moving straight to his groin, making things worse. Or better. He didn't know anymore.
"Destroy me", Dipper breathed out, soft sobbing following his own words, "Break me. Do with me as you p-please."
"And?", Bill whispered very close to Dippers ear, sending shivers through the young mans body.
"Fuck me."
Tears streamed down his face.

I'm so messed up.
Twisted.
I don't deserve to even be called a human.
I'm possibly causing a future apocalypse just by letting him near me.

But despite all of these thoughts, despite knowing just how wrong all of this was, Dipper couldn't help but admit that it felt so very, very right.
"Gladly..." the demon answered, his voice now husky and low. He let go of Dippers neck and reached for his belt, opening it and getting rid of his own pants. Why was he naked except for pants? Probably something Dipper had imagined some day, in some twisted dream.
"I've done this before, you know. Fucking with humans is always fun after all, no matter in what way", the demon tilted his head and looked at Dippers scared expression, his crying and weak struggle against his own desires. Bill's fingers touched Dippers lips, brushed over them, then a single one pushed into his mouth, in and out, in and out.
"But the difference is, no one has ever wanted me to do something like this. Not even Sixer. He was obsessed with me, and he kind of wanted my love or something like that, but even he would have never wanted this."
Bill simply watched as Dipper started to suck on his finger, probably pretending it to be something else entirely. After all these years, his little puppet was still full of surprises. And Bill couldn't even deny that he loved it.

Oh, they would have so much fun.

[Note: The next chapter has a time jump to a few weeks later, and also the first really explicit sex scene.]