"Okay kids, time to hit the hay!" Grunkle Stan yelled from downstairs, where he was watching a rerun of his favorite movie, The Duchess Approves. Dipper smiled to himself, glad to be finally fulfilling his end of the deal. Pretty soon, Mabel would be all his. He was barely able to change into his pajamas and brush his teeth, he was so jittery with excitement. At last, Dipper and Mabel were in bed.
"G'night, brobro!" Mabel called from across the room.
"Goodnight Mabel!" Dipper called, a smile in his voice. He closed his eyes and drifted off to sleep, ready to meet Bill in the Mindscape.
Dipper's Mindscape
Dipper seemed to open his eyes to find a dull white room, about fifteen feet by fifteen feet square. Light seemed to emanate from the ceiling, but there was no light fixtures. The only thing in the room was Bill.
"Hey Pine Tree!" said the human form Bill had taken, a naked, dark skinned man with yellow hair and an eye-patch. Dipper estimated his form to be about 20, but he knew the demon was actually older than the known universe.
"Let's get this over with," Dipper intoned, implying he was bored and ready to be with Mabel.
"Ah, look up Pine Tree. I know what you'll enjoy!" Bill snapped his fingers, and Dipper was naked with his hands and feet tied together in front of him, exposing his tight virgin asshole. Bill walked up, and a glowing, blue paddle of light appeared in his hand. He began to spank Dipper's perfect bubble ass, while Dipper screamed in pleasure and pain. "Have you had enough yet?" Bill inquired seductively.
"Ye-Yes!" Dipper replied.
"You will call me master!" Bill screamed, spanking Dipper so hard he began to cry.
"Y-y-yes master!"
"That's better, slave. Now accept my girth!" Bill snarled. He turned and stuck his 9 inch, pulsating penis in the boy's unprepared ass, causing Dipper to scream in pain. "Don't worry, slave. It'll be better." Dipper just whimpered in response. But Bill wasn't lying. As Bill slammed his dick into Dipper's prostate, Dipper began to feel better and better. All to soon, he felt the familiar release of orgasm coming on.
"I'm gonna cum!" Dipper gasped.
"Me too!" Bill moaned. "Ahhhooohh!" They moaned together as they both came, Dipper on the ground of his mindscape and Bill inside of Dipper. Bill slowly pulled out and took a look at his hot seed slowly dripping out of Dipper's stretched asshole. He smiled, observing his work, and took a swipe with his finger in order to taste his handiwork. When he was finished, he snapped his fingers. With a pop, Dipper was back in his pajamas and Bill was back in triangle form.
"Hey, thanks Pine Tree. Expect your part of the deal any time." Bill began to fade away, but Dipper quickly stopped him by grabbing on to one of Bill's corners. "Whaddya want, Pine Tree? Missed me already?"
"No, Bill, but about what just went down... if you're in the neighborhood, just, you know, stop by or something," Dipper said with a blush. "Oki Doki, Pine Tree. I think I'll take that offer sometime," Bill said with a smile. Bill faded to black, and Dipper closed his eyes to gather his thoughts.
Dipper sat up with a gasp. He looked over to check the time, finding it was seven o'clock. Dipper smiled in his mind, thinking of what was to come.