Special thanks to RasenganFin who gave me the idea to do a sequel of Gravity Falls: Pines Meeting. B. Bandit22 who's own fanfiction helped me come up with one of the plots for this story. And retro mania who is the reason Pines Meeting, the story that preceded this one, ever existed in the first place.

Warning, this chapter contains brief scenes of intimacy not meant for younger audiences.

Gravity Falls: The Pines Mystery

Sequel to Pines Meeting

Prologue

Spring break, a time for students to go on a mass party rush and get wild. Dancing, lots of drinking, (nonalcoholic depending on the age), loud music, and other fun activities. It was the perfect way to take a break before the hardest round of the semester began. And if that weren't enough, then having your birthday during the middle of this special week made it a thousand more awesome; which was exactly the case for Grenda Grendinator.

Turning eighteen and getting set to graduate in three and a half months, the muscular girls' friends were set to give her the best birthday ever. With tons of balloons, confetti everywhere, a soda fountain containing all of Grenda's favourite sodas, her top snacks/pastries, ice sculptures shaped like the birthday girl, and even One Direction performing live. Best of all, it was all happening on a private yacht docked on a small island in the Caribbean with all of Grenda's friends onboard for the party of the year.

Seemed expensive, though it's not like any of this was impossible. Afterall Grenda's boyfriend, Marius von Fundshauser, was the richest man in Austria, and number ten among the richest people in the world; all thanks to the most successful epaulet factory that he owned. With his wealth, there was no problem in acquiring everything needed for his girl's dream birthday.

And there was no doubt about it, Grenda was having a blast.

"Once again thank you. THANK YOU! THANK YOU!" Grenda, who now had the autographs of all the One Direction members tattooed on her forehead, said to Mabel and Candy while hugging them both tightly.

"No problem Grenda," Mabel squeaked. One thing Grenda was known for was giving overly tight hugs. Even those who were used to them, (Mabel and Candy in this instance), had difficulty breathing.

"That's what friends are for," Candy gasped out.

"Speaking of friends," Grenda said, releasing her BF's who took in as much joyous air as they could while she continued to talk. "I just found out the Stan and Ford are here. I gotta go greet them and remind the staff and crewmen Marius hired for the party to keep Stan from stealing anything. Could you keep an eye on my man over there while I'm gone?" she said, pointing to the as always, a stunning baron. "He's been acting very nervous, and not in a cute, sexy way if you know what I mean," she winked.

"Actually, I'd better go with you," Mabel said. "They are my uncles after all. Also, you know I can't let anyone onboard without a birthday sticker," she said, showing a pack of stickers of iconic birthday items with smiley faces on them.

"Can't say no to that," Grenda agreed. "Candy?"

"Oooooohhhhh, don't worry Grenda," Candy said blushing. "I'll keep a close eye on Marius. A very, very close eye. Ah-ha, ha, ha."

This creeped both her friends out a lot, (even Mabel). So, they both just slowly backed away, making their way down towards the gangway.

When they were out of her sight, Candy breathed and began to walk over to Grenda's very rich, and handsome, boyfriend of a man. "Here goes."

Warning: intimate scenes mentioned earlier shall be happening within the next two parts of this prologue.

The party was going smoothly. The food was awesome, all guests were present and enjoying themselves, One Direction was singing, and singing well, but one thing didn't feel right to the birthday girl, and that was the fact that she could not find either her boyfriend or best friend Candy.

After going to greet the original Pines Twins (Stan and Ford), Grenda had returned to the Skydeck to where she'd left the two, only to find that they were gone. She tried calling out to them, and even texted them, but go no response either way.

"Hey Grenda, happy birthday," Wendy said from behind the birthday, diverting her attention.

Turning around to face the lumberjack girl, Grenda saw Wendy and Dipper, arms wrapped snug around each other, and this got her complete focus as she smirked.

"Well, well, well. If it isn't the future Mr. and Mrs. Pines; or Mr. and Mrs. Corduroy depending on which name you guys choose to take."

This caused the couple to blush in embarrassment, while also feeling a bit pissed off. It annoyed the two whenever someone, namely Mabel, Grenda, or Candy, insisted that they were getting married and having kids.

"Grrrr, Grenda for the last time Dipper and I aren't engaged," Wendy remarked.

"Besides," Dipper added, "We've only been dating for five years."

"Exactly," Mabel popped out from behind some balloons. "You've been dating long enough. Plus, you're both adults now and you Dipper will be graduating from high school soon. It's the perfect time to settle down."

It should've startled her friends and brother, but at this point, none were surprised by the Pines girls' actions. Instead, they were more focused on the conversation regarding Dipper and Wendy's relationship.

"We've got college to focus on Mabel," Wendy protested.

"Which is gonna cost us an arm and a leg," Dipper added. "Not counting rent money for the new apartment we're looking at getting in Portland."

"I hear there are some pretty roomy apartments in Portland. Perfect place for you two to make babies in," Mabel smirked, not listening half of what her brother was saying.

"MABEL!" they both shouted.

"Oh yeah by the way," Grenda spoke up. "Mabel, have you seen Candy or Marius anywhere? Can't seem to find them and it's almost cake time."

"I think I saw them going below deck," answered Jeff, a dark-haired teen with brown hair and a light green t-shirt over a long-sleeved, dark green shirt, who happened to be the guy Mabel sent a rigged "Do you like me?" note way back in Gravity Falls, and was now her boyfriend. "Weird, Candy was blushing bright red and giggling all awkwardly."

"Sounds suspicious," Dipper commented.

"You say that about everything," Mabel said before kissing Jeff on the cheek.

"Yeah Dipper quit being so paranoid," Grenda commented.

"I'm just saying-"

"And I'm gonna go find two out of three of the most important people in my life," Grenda interrupted before going down to find Marius and Candy.

It took a bit of time, (longer than Grenda had hoped it would), for her to piece together were her friend and boyfriend were. Going below deck, she searched every room she came across, asked many guests, getting many responses leading her towards the cabins; eventually bringing her outside her own cabin.

There she heard moaning coming from inside. She tried opening it, but the door was locked; though Grenda had years of practice knocking down doors and in the snap of a second, BAM, she was in and found Candy and Marius.

Yet when she saw them, the big girl wished she wasn't seeing like they were now.

Candy, Grenda's best friend, (tied with Mabel Pines), Grenda's soul sister, (again tied with Mabel), was butt naked, kissing Grenda's boyfriend, who was also naked and kissing passionately; while ramming his dick inside her.

Surprisingly, the two were so caught up in their lovemaking that both had failed to take notice of the door being broken down. They only realized that Grenda was watching them when she…

"Wha, what, WHY?!" Grenda cried out as her eyes began pouring out tears.

Hearing this caused both to stop and look over, their faces turning from to complete shock and horror. "GRENDA?!" Candy gasped while Marius desperately pulled himself out of the latter and tried to cover himself up with a nearby pillow.

"Yo Grenda, you find Candy and Marius yet?" Mabel called out. Walking into the room followed by Dipper, Wendy and Jeff, the Pines girls' eyes bulged up when she saw what Grenda saw, and like her bestie, she was flabbergasted, along with the others also. At this point, Candy too attempted to cover herself with blankets from the bed, but it did no good to hide the anger developing inside her friends.

"Ca… ca… ca… CANDY?!" Mabel screamed.

By then Grenda couldn't take seeing her boyfriend and besties' betrayal anymore and ran out of the room. She made a beeline up through the yacht for the gangway, not caring about the people she knocked over, ignoring the concerned comments from those she pushed aside, or those attempted to follow her; such as Mabel, Dipper, and Wendy.

"Grenda, wait," Mabel called out, with Candy and Marius, (still covered in only bedsheets and pillows), close behind the Pines, desperately trying to apologize.

"Grenda I'm so sorry," Candy pleaded.

"Please my love, let me explain," Marius begged.

"I NEVER WANNA SEE EITHER OF YOU TWO AGAIN!" Grenda shouted, not stopping as she ran straight down the gangway, off the yacht to who knows where.

"You're dead to me too," Mabel said to Candy before running off after her heartbroken friend.

Dipper and Wendy followed suit, but not before giving Candy and Marius disgusted looks. "What the hell is wrong with you?!" Dipper shouted.

"Lowest thing I've ever seen," Wendy remarked.

At this point, it became clear to the rest of the party guests what had just happened, and as a result, they all gave the two "cheaters" looks of anger and disgust as well.

"That's your best friend! And you stole her boyfriend?!" Melody shouted.

"On her birthday?!"

"YOU WERE LIKE A SISTER TO HER!" Grenda's mother screamed.

"Just because you're rich doesn't mean you can hurt people," Pacifica spat to Marius.

"How could you do this?!"

"Grenda deserves better than you dude," Soos remarked.

"You're both pieces of junk. Especially you, you little slut," Stanley said, pointing to Candy before turning his attention towards Marius. "And as for you…"

Next thing anyone knew, the old conman sucker-punched the wealthy baron's face, followed by a knee kick right into his groins, knocking him off the boat and into the water.

This got cheers from the remaining party guests, plus a few crewmen/staff. Some even followed Stan's lead and threw their cups and other snacks at the disgraced baron, and then at Candy; forcing the almost naked girl to run back inside the boat and hide in the room where she'd betrayed her best friend.

Unbeknownst to everyone, at the exact moment that Marius cheated on Grenda, a dark storm begun to develop in the area surrounding Vienna, capital of Austria, Marius' home country. Oddly enough the weather had predicted sun throughout the entire week, and moments before there hadn't been even a single cloud in the sky. Now dark clouds and howling winds engulfed the area, pouring out thunder and powerful bolts of lightning, along with rain coming down like tiny daggers that cut anyone/anything it touched. According to weather reporters, the eye of the storm appeared to be happening around a large mansion located near the center of the city; a place that was well known to all of Austria as the Fundshauser family Manor. Yet despite there best efforts, any intel regarding the cause of this sudden storm, or its connection to the massive mansion remained unknown.

Inside the main hall of Fundshauser Manor hung a massive portrait where everyone who walked in could see it. The portrait was of a young, elegant looking woman with chocolate brown hair, smooth light skin, a gorgeous yellow dress, and a peaceful smile. But then a bolt of light struck right beside a nearby window, casting a quick, bright glow over the portrait for a short instant. In that millisecond the woman in the portrait changed significantly: her skin now appeared pale and wrinkly. Her dress, along with her hair, was now palish grey, messy, and torn up. Her face, what was once a peaceful and happy instead now had a frow that showed anger, pain, betrayal. What was once a beautiful portrait had in an instant become terrifying. And then what made this even scarier was when the portrait began to shriek, her voice heard throughout the entire house, sending jolts of pain to all within. "What. Have. You. DONE?!"

After an extensive search, Mabel, Dipper, Wendy, and a few others found a heartbroken Grenda and brought her back to the boat where she was greeted with open arms by the remaining party guests. They then soon left the yacht, feeling as the party was over and Grenda wasn't in the mood for any big celebrations. Grenda too decided to leave as well, feeling uncomfortable sleeping on board the same boat that her ex-boyfriend and her worst enemy were on. Mabel and Jeff joined her and went to a nearby hotel to stay for the night. Dipper and Wendy decided to go to the same hotel as well, though they took a different/longer path towards the hotel. Both felt that Grenda wasn't in the mood for too much company, and Mabel would be able to cheer her up herself; plus they did plan on exploring the island a bit.

"I can't believe Candy slept with Grenda's boyfriend. The guy she'd been dating for over five and a half years now," Dipper said to Wendy.

"Tell me about it," Wendy replied. "I've seen a lot of affairs at parties, and have been caught in the middle of a few myself, but this one is by far the worst."

"Let's hope Grenda can recover from this horrible betrayal," Dipper sighed.

"With Mabel by her side, I think she'll manage, though it's gonna be a long, long while before she considers dating again."

"No doubt about…" Dipper stopped midway when his eyes caught sight of a piece of jewelry resting behind a glass window of a local shop in front of him. For some reason, his eyes were drawn to this particular piece of jewelry, as it shined brightly.

"Yo Dipper… Mason," Wendy called, having walked a few feet ahead before realizing her boyfriend had been standing in front of the store window.

"Um… I… uh… I'll catch up. Just gotta check something out," he stuttered. He hoped she didn't get curious and wonder what he was so interested in.

To his fortune, she wasn't. "Don't take too long," she called out before walking further away till Dipper could no longer see her. After which he then walked into the store to purchase said item.

F.Y.I. Grendinator is Grenda's actual last name according to her profile page on the Gravity Falls wiki. I'm as surprised as all of you who didn't know before this.

Also, I hope you all liked the first part of Pines Return. Please feel free to follow, favourite, and review this fanfic.