Chapter Four: The Rest of Summer and a Night of Passion and Confessions

The time when the kids would have to move to Michigan to go to Crystal Lake was drawing nearer. Dipper had released Miles and Stan from being grounded, reasoning that they would be leaving the state soon and that they should have the time to say goodbye to their friends and just have fun. He had forbidden Miles and Stan from going to the immortality spring though, and had further forbidden them from taking anyone else or telling anyone about it.

The fact that Miles had probably gained immortality from the spring at thirteen was enough of an issue. Dipper, Wendy, Pacifica and Mabel had been adults when they'd gone into the spring. Miles was just a child. They would have to figure out what to do. They would have to figure out whether Miles would age to adulthood normally and then stop aging, whether he would age to adulthood slowly or whether they would have to use his abilities to age himself up. Would he even have those abilities from such a short dip in the spring? Would the fact that he was still soaked when he got home mean he did have the abilities?

Or would the fact that he hadn't been in the actual spring for more than a minute mean that he wouldn't have any more than regeneration and immortality? Dipper was working on furthering his alchemical knowledge with Ford, who had studied alchemy in another universe. He considered it more of a science than magic was. Alchemy required some level of precision in application or else the rituals wouldn't work. Dipper was working on a method that would allow them to age normally for another ten years. They would age from the point that they were at.

In Dipper's case, he would start aging at about the age of 23 to the age of 33 while Wendy would age from about 25 to 35 or 37. He still had some work to do on it before he was comfortable sharing it with his son. He would undoubtedly test it on himself to see what if any other effects it had on him. He had already tested a serum that was supposed to expand his abilities and discovered an expanded ability to manipulate his own physical abilities and a growing resistance to physical damage. The thing he worried about was that he might one day become so strong and so resistant that he was no longer human.

And what then? Should he share his discovery with Mabel, Wendy and Pacifica? He didn't know. But what he did know was that he should figure it out quickly before people started to notice that Miles wasn't aging. Already, the family was seen as odd, not really due to the bionic organs. Those had become common enough in the world, and while Dipper and Ford pressed for them to be accessible to those with Medicare or Medicaid, they weren't yet, save under extreme circumstances, and even then, only the single organ that was absolutely needed and couldn't be replaced with a flesh organ.

Dipper had some hope for the future.

"Hey, Dipping Sauce… Can I ask you a really big favor? Like the biggest favor a sister could ask her brother. But I need you to be really, really cool about it." Mabel said, not bothering to knock. She knew Dipper often neglected his own needs, including but not limited to food, showering, being intimate with his partners and getting some natural sunlight. Because of his regeneration, he stayed in pretty good shape, with the limited exercise he got.

But Mabel worried about him and tried to shake up his schedule sometimes.

"Oh, just come right in." Dipper said.

"Not like I'm an adult male. Who knows what I'm doing in here?" Mabel laughed.

"Please, Paz and Wendy tell me you haven't given your meat pole any love in weeks. And they want to change that… I do too…" Mabel smirked.

"That's what you want me to be cool about? Having sex with my own twin sister?" Dipper asked. Mabel shrugged.

"Why not? We're adults, both of us are over 30 now. It's not like we can't make our own decisions about who to have sex with. We have condoms more advanced than anything on the market. We have pills that I can take if something bizarrely does go wrong with the condom. And Wendy and Paz want to join in. Think about it. I get my fantasy of being double penetrated by a guy and a girl.

"You get to have sex with the three hottest girls in Gravity Falls."

"Great. I've always wanted to have sex with the hottest girls in Gravity Falls. When do they get here?" Dipper teased. Mabel playfully slapped Dipper in the back of the head.

"Oho! You're gonna get it for that! Just for that, Paz and I will double penetrate you." Mabel laughed.

"Hmm… It's not like I never considered trying out being pegged. Just be gentle. It's my first time putting anything bigger than a fairly slender dildo up there." Dipper said distractedly.

"You got it, bro-bro. After the kids go to sleep tonight, meet us at Deirdre's old house. She apparently left already. Not sure how, but whatever. She does have a model of our teleportation app." Mabel said.

"What? She does? When did you give her that?" Dipper asked.

"That's what you want to know? Not you wish she could have joined us? Not you wanted her to suck you off?" Mabel asked.

"Nah. I know you and she broke up, and I don't mind if you have some fun with Wendy and Paz.

"Paz denies it still. Says she's just willing to play along for Wendy's and my sake. But I know she's bisexual. I dunno why she lies to us about it. Nothing wrong with liking sex with other women." Dipper said. Mabel nodded.

-0-

That night, Dipper thanked Ford for keeping an eye on the kids and he went out, going across town to Deirde's old house, knocking on the door. He could see Mabel inside. She was already naked, making out with Pacifica.
"Password!" Mabel demanded.
"Just let me in, Mabel!" Dipper demanded.

"That's not it." Mabel laughed. Wendy wrote something on her hand and showed it to Dipper, who blushed heavily.
"Let me in so I can… Rail my sister's hot ass…" Dipper turned an even brighter red, if that was possible.
"There ya go!" Mabel laughed, letting Dipper in, her hand already teasing down his stomach.
"Mmm… Considering how little exercise you get these days, you still look pretty good there, Dippy Doo." Mabel smirked, kissing him passionately as she reached down past his waistline, causing Dipper to gasp.

"Hmmm… You're already showing a pretty nice hadron for me, huh big guy?" Mabel breathed. Dipper was trembling. It had been a while since he'd slept with Pacifica or Wendy. He'd been really engrossed in his research lately, trying to figure out how to perfect controlled aging within an immortal via Body Manipulation and/or Biological Manipulation. It was a difficult task and he was getting better at it. He was hoping to create a biological program within his own body so that he could continue to age without having to think about it.

"Dipper… Stop thinking… Just let yourself enjoy this." Wendy said.
"It's not every sister who'll actually put out for her brother." Mabel smiled, biting Dipper's neck hard, causing him to squeal loudly.

"Oho! Didn't know you liked that kind of thing… Huh, there?" Mabel couldn't help laughing at the noise her usually calm and collected brother had just made.

"So how do you want this to go? You want me to give you a nice hummer first? Or should we skip to the main event?" Mabel smiled.
"Why don't we get up to bed first. We can take it one step a-ahhhhhaahhhh!" Dipper gasped as Mabel started stroking his shaft.
"Go on. One step what?" Mabel asked, still stroking him.

"O-onnnee… S-step… Oohh! Mabel!" Dipper was already panting eagerly.

"Hmmm… You really are pent up. Let's hope that means you're good for a bunch of rounds." Mabel said.

"Ahhhh! A-at… At a t-tIMEE!" Dipper growled loudly as he climaxed. He tried to pull his pants down before he finished, but his climax hit him hard and his legs nearly buckled under him.

"That's quite a load. I'm glad this house has a washing machine." Mabel said, going upstairs with Dipper, Wendy and Pacifica.

They got into the bedroom.
"So, princess. You wanna go with me first?" Wendy asked.
"Fine… But only because I know how much you like it. I'm straight." Pacifica said. Wendy smiled.
"Okay. I appreciate that." Wendy said. She didn't want to pressure Pacifica into officially coming out of the closet, though it was pretty much the worst kept secret in Gravity Falls that Pacifica was bisexual. She'd had sex with Mabel and with Wendy before, and unless she was a really good actress, her orgasms were real.

"So, Dippy Doo… Let's see what you're packing. It's been a while since that night in the hot spring and I was a bit high then." Mabel said. Dipper had made sure that Mabel didn't see him naked again after that night. Mabel was pretty sure it wasn't conscious for him, but he didn't want to risk going too far with Mabel again. But now, she had him right where she wanted him.

"Wowza! Did you get even bigger since you were 18?" Mabel gasped. Wendy laughed.

"I think he did." The redhead chuckled.

"Sorry… I didn't mean to… Maybe my Biological Manipulation has been affecting me." Dipper said shyly, trying to cover himself in embarrassment. He was still adorably shy when it came to people seeing him naked. He locked the door when he took a shower and when he went to the bathroom. And you'd think that he wouldn't have a problem with Wendy or Pacifica seeing him naked, but he got flustered the one time Wendy suggested they have sex with the lights on.

"Hey, it's okay. We can handle this. You shouldn't feel embarrassed about it. Men are willing to spend lots of money on fake remedies to make them bigger." Mabel said, kissing his manhood, breathing lightly on it and flicking her tongue out over it. Dipper moaned loudly, his hands weaving through her hair, grabbing her head. He had a strange light in his eyes as he growled under his breath.

"Open it." He ordered in a low, almost predatory growl. Mabel couldn't believe what a turn on this was. She opened her mouth, almost gagging as he pushed her head down on him.

"Mmmm… Y-yeah…" He breathed, moving her back and forth. Mabel had put vaporizers around the house that would dispense an unscented, tasteless aphrodisiac. Mabel didn't expect Dipper to be this energetic from it though. She gagged and gulped as he thrust into her, growling out his release deep in her throat. Mabel panted as he let her go. Her face was flushed with arousal and panting from lack of oxygen. But this version of Dipper was incredible.

"Do-do you want to take my anal virginity? I've never had an actual dick in my butt." Mabel breathed eagerly.

"Oh… Um… Have you used toys? I don't just want to go digging in there. I know I'm pretty big." Dipper breathed.

"So modest." Wendy teased, still gasping and moaning as she scissored with Pacifica. Dipper blushed.

"You're fine. I've used dildos and vibrators before." Mabel said, getting in a comfortable position on the bed. Dipper nodded and put on a condom. Ford had invented condoms that would expand or contract to fit the size of the individual, so they were effectively universal condoms. For all but the biggest or smallest penises, they would work just fine.

"You-you ready Mabel?" Dipper asked, putting extra lubricant on the condom. Mabel nodded, already anticipating how it would feel to have something as big as Dipper's inside her butt.

"G-go… Slow…" Mabel breathed as Dipper slowly pushed inside her rear end, teasing her clit with his fingers as he moved. Mabel let out a long gasped, feeling her butt and stomach clench as he entered her.

"Mmmm… S-sooooo bigggg…" Mabel moaned, biting her lip in pleasure.

Dipper began to thrust inside her, grunting lightly as Mabel squealed in delight. The sounds the twins were making were getting Wendy even more turned on as she pulled Pacifica up, kissing her passionately.

Dipper groaned as he slapped Mabel's butt hard, causing Mabel to climax almost immediately. She let out a choked scream as her knees nearly gave out with her orgasm. Dipper didn't stop though. He continued to thrust inside her butt, slapping her behind.

Mabel cried out, practically barking as Dipper's thrusts got harder and faster, finally finishing himself, grunting as he filled his condom with his seed.

"Mmmm… Th-that… That was awesome… You… You want to raw dog me in my kitty cat?" Mabel asked. She could take a pill that was more effective than a standard condom in the morning if she wanted to. Dipper gulped.
"Are you sure? I don't want to accidentally get you pregnant." Dipper said.

"I'm sure. I can take a pill if it makes you feel better. And besides, there's no man I would trust more than you to be the father of my baby." Mabel said.
"Mabel! Have you considered the threat of birth defects in an incest baby, especially between twin siblings." Dipper breathed.

"Dipper… For once… For once, don't think. Just let yourself enjoy it." Mabel said gently, kissing Dipper lovingly on the lips.

Dipper nodded, cleaning himself off a bit and resting for a few minutes to recharge. After three arrivals in less than an hour, he needed to take a break.

"H-hey! No kissing! I told you! I'm straight!" Pacifica protested. Wendy chuckled. This had to end. Pacifica had to stop lying to herself.

"Come on, Paz. You've asked me for sex at least five times when Dipper is busy with his research and development."

"A p-paahhhhh! P-partner… O-of conv-venience…" Pacifica gasped and moaned as Wendy continued to grind in time with Pacifica.

"You say you love it when I play with your boobs."
"I l-love having my boobs played with… Th-they are pretty awesome… Nice fat 42Cs. All natural." Pacifica smirked, trying to be cocky when she just sounded desperate, especially with her panting and squeaking and moaning.

"Well then… I guess you don't mind if I stop." Wendy shrugged, starting to pull away from her.

"N-noooo! Please d-don't stop! F-finish me off!"
"Finish me off, what?" Wendy demanded.
"F-finish me off, Mistress? I'm a bad girl! Punish me…" Pacifica begged.

That was another thing not many people knew. Pacifica loved to be dominated, by men and by women. She loved letting someone else take the reigns.

"Get on your knees, worm." Wendy ordered. Pacifica turned bright red, her eyes lighting up with excitement, dropping to her knees in front of Wendy.
"Now, eat." The redhead ordered. Pacifica eagerly started eating Wendy out. The freckled lumberjack moaned, stroking Pacifica's head lightly.

"Mmmm… G-good girl…" Wendy breathed, gasping, sitting down on the bed and just letting Pacifica do her word.

"Now… Tell me… Are you straight?" Wendy asked.
"N-no…" Pacifica moaned as she fingered herself, continuing to pleasure Wendy.

"Good…"
"I'm bisexual…" Pacifica breathed, smiling as Wendy climaxed and the blonde licked it all up.

"You ready to start again, Dipper?" Mabel asked after they watched Pacifica finish Wendy off and Wendy start to do the same to Pacifica.
"Yep. After that show, absolutely." Dipper said, kissing Mabel lightly on the neck.
"Mmm… B-bite me… Make me your property…" Mabel begged. She didn't really realize until now just how attracted to Dipper she really was. They were very different people, but Mabel admired how dedicated Dipper was to his work, even if it caused him to neglect his family sometimes.

She would have to bring him out of that habit. Dipper bit down hard on Mabel's neck, causing a loud, aching moan to escape her lips.

"Mmm… Th-that's the stuff…" Mabel breathed as Dipper kissed her breast lightly.
"You like playing with boobs, don't you, Dippy boy?" Mabel smiled. Dipper nodded, continuing to grope and kiss Mabel's breasts.
"Well, they're all yours…" Mabel breathed.

"Have you been working out lately, Mabel?"

"Deirdre made sure we both kept on a good exercise regimen." Mabel said, regretting now that she'd let Deirdre go. Maybe she would look Deirdre up in Cork, Ireland.

"Mmmm… You ready to park your car in the garage?" Mabel asked. Dipper nodded.

"Can I make out with you while we're having sex?" Dipper asked. Mabel laughed.

"Of course you can! Dipper, I may be your sister, but this is still a loving act." Mabel said, gasping, trying to adjust herself as Dipper pushed into her womanhood. She panted and gasped, her nails digging hard into Dipper's back.
"O-ohhh! F-FUCKK! FUCK! FUCK! FUCK! S-SSOOOO BIG!" Mabel cried out. Dipper hardly ever heard Mabel cursing, so this was unusual. He tried to slow down, but Mabel was so snug and wet. It felt incredible inside her that he couldn't help continuing to move.

He kissed her passionately.
"I love you, Mabel…" Dipper breathed as his thrusts started to get faster. Mabel whined in pleasure.
"I-I love you too, Dipper! Please! Don't-don't stop! K-keep going! Oooooohhh…" Mabel gasped. She could feel herself getting close. Dipper grunted though, burying himself inside her and letting out a long snarl, filling her with his seed. Mabel sighed as he pulled out.
"Can you finish me off, bro? That was awesome. I'm almost there. Just need a little bit more of a push."

Dipper nodded, kissing her between her legs, eating her out until she got the rest of the way there, finally lying down next to Mabel, kissing her lovingly on the lips.