Authors note: Surprise! Another new story. Yes, I know that I have other stories to tend to, but I figured that I would do this story because it's been a long time coming. I've always wanted to do a crossover with Godzilla and Gravity Falls since no one else in the world has thought of it yet. And after watching every single Godzilla movie in a marathon because I have no life, I decided fuck it! Let make this happen. Not too many things will happen in the first few chapters since it's all set up, so be patient for monster action. Be sure to review and PM me if you have any suggestions to improve the story as we go along, cause it's going to be a while until it's done. Hopefully you guys will enjoy it.

P.S. - Consider this an EXTREMLY late anniversary gift for Godzilla's 60th birthday.

Chapter 1: Welcome Back

O-O-O

Summer vacation for the twins couldn't have come any sooner for Dipper and Mabel. It had only been two years since the twins visited Gravity Falls, but the twins insisted to their parents that they wanted to go back to visit their Grunkle Stan as soon as summer vacation began. Although surprised at the twin's insistence, the parents happily agreed since their kids told them how much fun they had at Gravity Falls, except the parts that involved fighting the supernatural and possibly dying. Dipper and Mabel knew their parents can be overprotective and telling them all of their close encounters with death is the last thing they wanted to do, so they just left that part out.

The twins also changed a bit as well, now being fourteen meant they are now teenagers and growing up had its perks. Dipper's voice was now a little deeper than before and didn't crack as much and even started to grow some facial hair, though not very noticeable, while Mabel finally got her braces off, showing off her pearly white smile instead of one with metal. The twins also grew a few more inches, though Mabel still had one millimeter on Dipper, but other than that the twins were still the same people as before.

Dipper was still the intelligent adventurer as before, always wanting to solve mysteries at every corner, albeit over-zealously at times, but still rational and mature for his age, while Mabel is still the spirit full optimist, always being friendly to people and still as boy crazy as ever, despite being naïve at times and even when her feelings are hurt, she still looks to the bright side of things. Despite their clashing personalities, the twins still share a strong bond and it only deepened with their last visit to Gravity Falls.

The twins were now waiting at the bus stop with their parents, all packed up and ready to go with suitcases in hand. Dipper wore his usual t-shirt, vest, shorts, and shoes, along with his signature blue and white pine tree cap while Mabel had on her usual skirt, sneakers, and her newest sweater she knitted which was light blue with a cat's face on front. When the bus finally arrived, the twins hugged their parent's goodbye and went to the back of the bus and stood on top of the seats, waving to their parents as they did the same.

"Bye Mom! Bye Dad!" Shouted Mabel waving to her parents as the bus began moving.

The twins then sat down on their seats, putting their cases underneath their seats and got comfortable, knowing that it was going to be a long ride to Gravity Falls. The twins had a small moment of silence before Dipper broke it with a yawn.

"Tired already? We just got on the bus." Said Mabel as Dipper rubbed his eyes.

"We just woke up half an hour ago Mabel." Said Dipper.

"So what?" Mabel said unconvinced.

"It's 8:00 A.M."

"It was YOUR idea to wake up early Dipper. It's not my fault I'm an early bird." Said Mabel as she flap her hands like wings and spoke "TWEET! TWEET!" in a high pitched voice.

"Good point." Said Dipper before yawning again, making Mabel yawn with him.

"Oh man, I have the yawns now." Said Mabel as she yawned almost in sync, making Dipper smirk.

"Well, I know one thing that'll wake me up." Said Dipper as he took out a book from his vest.

"Really Dipper, reading? That so BOOOOOORING!" Said Mabel.

"Not if it's a good book." Replied Dipper as he pointed at the cover of the book, which had a six fingered hand and a number 3.

"I can't believe Grunkle Stan actually let you keep the journal." Said Mabel somewhat surprised.

"I'm just glad that he didn't charge me for it." Quipped Dipper as he and Mabel laughed.

"I wonder how everyone is doing back at Gravity Falls, especially Waddles." Said Mabel sadly.

"You know Mom and Dad wouldn't let him come with you, he's a pig after all. Besides, Soos said he'll take care of him for you." Assured Dipper.

"I know but… I miss him." Said Mabel as Dipper put his arm around Mabel to comfort her.

"I know how you feel." Sighed Dipper as he thought about Gravity Falls.

The day that Dipper and Mabel had to leave Gravity Falls was hard for them and it was even harder to say goodbye to their Grunkle and their new friends, the twins knew that they would never have another experience like Gravity Falls again, never meet the same kinds of friends, the same kinds of mysteries, even the same kind of smell from your Grunkle's bad morning breath, Gravity Falls was like a second home to the twins, except cooler. Now that they were going back to Gravity Falls again, they had never been happier.

"Boop." Said Mabel as she poked Dipper's nose, making him chuckle before going back to her cheerful self. "I shouldn't worry though, we get to see everyone we know and love again. Waddles, Stan, Soos, Wendy, Candy, and Grenda will all be there waiting for us." Said Mabel cheerfully. "Kind of at least."

Dipper looked at Mabel curiously. "Didn't Mom and Dad tell Grunkle Stan that we're coming back?"

"They were about to, but I convinced them that we're going to surprise him and everyone else at the Shack. They'll be so happy to see us again." Said Mabel giddily.

"Or, he'll get a heart attack from our sudden appearance." Said Dipper concerned

"Oh, stop it." Said Mabel as she playfully shoved Dipper.

Mabel yawned again, this time she was actually tired and she laid her head down on her brother's lap.

"Tired already? I thought you were excited to go back?" Dipper remarked.

"I am, but I was awake all night, I even had everything packed." Said Mabel groggily as she started to drift into sleep.

"I'll wake you up when we get there." Said Dipper, gluing his eyes to the journal to find any new mysteries he may have missed.

"Thanks Dip." Said Mabel as she drifted off to sleep.

O-O-O

"Last stop! Gravity Falls!" Announced the bus driver as the bus stopped at the Mystery Shack.

Hearing the announcement, Dipper put away his journal and looked at his watch to see that it was noon and gently nudged Mabel to wake her up.

"Mabel? Wake up, we're here." Dipper softly spoke.

Mabel suddenly rose from Dipper's lap, making Dipper almost fall off from his seat at Mabel's sudden movement. Looking out the side window, Mabel gasped out of glee at what she saw.

"OH MY GOSH DIP! WE'RE BACK! WE'RE FINNALY BACK!" Mabel gleefully shouted as she saw the Mystery Shack.

The shack looked the same as it was two years, it still had the 'S' from the sign hanging down, it still looked somewhat run down, and it still attracted tons of tourists to behold the "wonders" of Gravity Falls, seeing the group of tourists that came off the bus the twins are still on.

Dipper and Mabel grabbed their suitcases and walked out of the bus, Mabel being the first to get off while Dipper paid the bus fare money his parents gave him for the trip.

"You kids watch out for your wallets, rumors say the owner is some kind of con artist." Warned the bus driver.

"Thanks for the warning sir, but we met this con artist before." Said Dipper unworried.

Dipper then got off the bus and as it closed behind him, it turned around and drove back to where it came from. Dipper then saw Mabel speed off straight towards the Mystery Shack, dropping her suitcase in the process, and then began running behind her to catch up to his sister while grabbing her suitcase she dropped.

"Hey, slow down!" Shouted Dipper to his sprinting sister as he struggled to run while carrying two suitcases with him.

"Hurry up! Come on, come on!" Said Mabel excitedly, not noticing Dipper holding all the luggage, struggling to keep up with the energetic sister.

When Mabel finally reached the front door, she waited for Dipper, tapping her foot impatiently until Dipper finally caught up to her, panting heavily as if he just ran a marathon.

"Geez Mabel, I thought you were tired." Said Dipper, still out of breath. "You didn't have to run all the way here."

"Oh stop whining Dipper, exercise is good for your health." Said Mabel panting slightly. "Feel the burn!"

"I just ran all the way here with two full suitcases." Said Dipper as he dropped the luggage, which helped calm his breathing. "I feel more than the burn."

"You need to follow my guide to exercising, then you wouldn't have those noodle arms still." Said Mabel poking her brother's arms.

"How about we go see Grunkle Stan first. Then, you can criticize my arms." Suggested Dipper as he tried lifting the luggage.

"Let me help." Mabel said as she helped carry the luggage and opened the door to the Shack.

Dipper nodded as Mabel grabbed her suitcase, while Dipper grabbed his and entered the Shack's gift shop. As expected, they saw all the overpriced souvenirs and a few of the exhibits that they made for their Grunkle last year, reminding them of good memories. The twins then heard a familiar voice talking to the group of tourists from the bus they got off.

"Welcome ladies and gentleman, to the Mystery Shack! The only place in Gravity Falls where all kinds of strange creatures and artifacts can be found." Said a deep and gruff voice to the tourists.

The twins looked at the tourist group to find the source of the voice, but the tourists were in the way of the familiar person they wanted to see, unaware of the twins presence as the voice continued to speak.

"For example, take a look at this thing!" Said the voice acting shocked, as the twins saw an 8 ball cane point to an exhibit that looked like a giant question mark with a pair of googly eyes glued on. "Is it just a question mark? A freak of nature? Your face on Monday mornings? So many questions!"

The tourists gawked at what they saw and began taking photos of the giant question mark, buying into the cheap scam in front of them. The tourist group then moved away to the other exhibits, behind a curtain leading to the museum inside the Shack, revealing an old man who was behind the scamming to the twin's joy, their Grunkle Stan.

He still looked the same as last summer, with his fancy suit, fez and 8 ball cane, he even had his eye patch on for the tourists so he would look more "mysterious" to them, though the real mystery was why tourists even bothered coming to the Mystery Shack still, not even Sherlock Holmes and Batman combined could figure that out. But that didn't matter to the twins as they called out to their Grunkle.

"Grunkle Stan!" Dipper and Mabel shouted, grabbing Stan's attention as he recognized the familiar voices.

"Kids?" Stan spoke out as he saw the twins drop their luggage and run towards him.

Next thing he knew, Stan was in a tight embrace with his great niece and great nephew, who he hugged back in return. After a few seconds, the twins and their Grunkle pulled away from each other.

"I didn't think you kids would come back here." Said Grunkle Stan, still surprised at the twin's unexpected arrival.

"Of course we would Grunkle Stan!" Said Mabel happily.

"There's only one crusty old Grunkle we would want to spend the summer with." Agreed Dipper, making Stan smirk.

"Wow… look at you two." Said Stan as he noticed the twin's growth spurts. "Growing up so fast, not as fast as me racking up cash from these tourists but still fast."

Dipper chuckled at Stan's quip. "Good to know you haven't changed a bit."

Commotion could be heard from the museum, signaling that Stan would have to go back to work shortly to guide the tourists.

Stan frowned. "We'll catch up later kids. Got to make sure these suckers don't touch the merchandise." Stan called out in the direction of the museum. "Soos! We have special guests!"

As soon as he Stan called, Soos appeared out of the curtain, looking ready as usual when something needed fixing. Soos looked pretty much the same as before, except it looked like that he lost a few pounds but that's about it. Soos then saw what Stan meant by "special guests" and called out to the twins.

"Dudes!" Exclaimed Soos as he bear hugged the twins in a tight embrace, while Dipper gasped for air.

"Soos we… can't breathe." Strained Dipper as Soos let go of the twins, who looked like they almost turned blue. "And I just… started breathing… again." Dipper panted between breaths.

"Sorry dude, I didn't know you'd be here again." Apologized Soos as he turned to Mabel. "But I know someone else who missed you more than me, hambone."

Soos the stepped out of the way to reveal a pig behind him that squealed happily seeing Mabel.

"Waddles!" Shouted Mabel happily as her pig jumped right into her arms, Mabel holding him tightly and gave him a big smooch on the pig's forehead.

"Okay, I'm gonna go now before all this mushy stuff makes me throw up my breakfast." Said Stan walking towards the curtain. "Soos. Help the kids unpack at the attic."

Soos saluted Stan as he went into the museum. The handyman picked up the twin's luggage and headed out the Shack to the main entrance for the living area of the house, with the Pine twins and Waddles in tow. While walking out, the twins and Soos could see a familiar red head girl with a lumberjack hat and green flannel shirt, pedaling on her bike right towards them and held the brakes to skid to a close stop.

"I know Soos, I'm running late again. Just tell Stan I-

The red head then stood in place after getting off her bike, just noticing the twins in front of her as she looked at them surprisingly, but then smiled out of glee.

"Hey dorks!" Exclaimed Wendy happily, as she went up to the twins to give them both a bear hug. "And here I thought this summer was going to be boring again."

"Can't…breathe again." Strained Dipper again as Wendy let go of the twins, leaving Dipper to catch his breath again. "How many times… will this happen?"

The two years away hadn't changed Wendy much either, she still wore her usual outfit that she wore two years ago, and still had her cool attitude, though deep down she wanted to explode with joy. Her last summer had been the most boring summer ever, even with all the supernatural occurrences in Gravity Falls, it wasn't the same without the twins. Now that they were here, she knew her summer just got interesting again.

"Huh, look at you two. You're almost as big as me." Said Wendy, comparing her height to the twins.

"I'm still bigger than Dipper." Gloated Mabel, showing off her one millimeter to Dipper. "Alpha twin! Alpha twin!"

"We never agreed to that." Interjected Dipper, making Wendy chuckle at the twin's antics.

"Oh man, this is totally going to make up for last summer." Said Wendy as she went up to the front door. "I really don't want to go now, but you guys know Stan."

"We get it." Said Dipper, nodding his head understandably as Wendy opened the door, but then turned to face Dipper before going inside.

"Oh uh, Dipper. We can catch up when you're done unpacking, I'll be waiting for you at the counter." Said Wendy, giving Dipper a friendly nod before entering the Shack, making Dipper smile warmly.

"Awwww." Said Mabel teasingly, playfully shoving Dipper's shoulder with her arm. "She missed you."

Dipper just blushed out of embarrassment, not able to come up with anything to say as he scratched the back of his head and went with Soos and Mabel to the other side of the Shack.

He missed her too.

O-O-O

"Here we are." Said Soos, revealing the old attic to the twins as he set down their suitcases.

The old attic room was just as empty as the first time they saw it, all that was left were two beds across from each other along with a small table and desk drawer, the attic room didn't look as dusty and dirty as they thought it would, it looked like it was cleaned on a daily basis, as if the twins never even left in the first place.

"Did you guys know we were coming? Because this place looks spotless." Dipper asked Soos, noticing the cleanliness of the room.

"Stan said I shouldn't tell anyone this but between you and me dudes, he's been asking me to keep this place clean ever since you two left." Answered Soos.

"Wow. That's really sweet but kind of creepy at the same time." Said Mabel. "Mixed feelings!"

"I'll help you dudes unpack now." Said Soos as he opened the twin's suitcases.

But before he could do anything, Soos heard Stan call out for him from below the attic.

"Soos! The outhouse needs to be cleaned out again!" Called out Stan, as Soos shuddered at the mention of the outhouse.

"And so, I must delve deep into the dark abyss. Wish me luck, dudes." Said Soos dramatically, going down the attic door to leave the twins to unpack themselves.

"Well, so much for getting help." Said Dipper, as the twins unpacked their belongings.

"At least not much has changed." Said Mabel, glad to be back in the Mystery Shack again. "It's good to be back."

"It is. Now I have the whole summer to investigate the mysteries of this town again." Said Dipper happily.

"Really? Don't you want to have a normal summer vacation here instead?" Asked Mabel, not too pleased about Dipper's intentions.

"That's as normal as summer can get here." Answered Dipper.

"You and your mysteries." Said Mabel, rolling her eyes at Dipper's answer. "Just promise me that you won't go off in one of your mystery hunts without me. Someone has to watch your back for squirrels."

"Not much of a hunt unless I have a party." Chuckled Dipper.

Then Dipper had an idea pop up in his head, as he stopped unpacking to look through his journal.

"What are you doing?" Asked Mabel, looking at her brother flipping through the journal.

"I know what we're doing today." Answered Dipper, stopping on a certain page of the journal as Mabel walked next to Dipper to see what he was looking at. "I found this in the journal while you were asleep on the bus."

Dipper pointed at the page he referred to, which showed a drawing of some kind of large rocky cave with a description of the page's topic on the side as Dipper began reading it out loud.

"On one of my many travels in the deep woods of Gravity Falls, I've found a hidden cave that could possibly lead to the discovery of a lifetime or just a bunch of rocks. Either way, there's only one way to find out." Read Dipper.

"That's it?" Asked Mabel, expecting there to be more than that.

"Unfortunately, yes. When I turned this page, I couldn't find anything else about the cave." Said Dipper, turning the page to show small bits of paper sticking out from the spine of the book. "It looks like that any other page about the cave was torn off from the book."

"Huh. That's pretty weird. You know what else is weird?" Asked Mabel.

"Well, there's also-

"Poke!" Exclaimed Mabel, playfully poking Dipper on his nose.

"I think you just answered your own question." Said Dipper, chuckling as he rubbed his nose.

Mabel smirked at her brother's wisecrack as the two went back to unpacking their belongings to furnish their room.

"Seriously though, we should go to this cave, it'll be fun." Said Dipper, trying to convince his sister. "It'll be just like when we were twelve."

"Well… we could die a horrible and painful death at the hands of a scary monster." Said Mabel, pondering if she should agree with the mystery hunt. "But since you said its fun, I'll go for it."

"Thanks Mabel." Said Dipper, appreciating Mabel's reluctance to follow Dipper into uncertain doom.

"What are twins for? Besides, we can catch up with everyone else when we're done unpacking before we go." Said Mabel, eager to talk to Stan, Soos, and Wendy. "I wonder what else happened in the town for the two years we've been gone."

"Only one way to find out."

O-O-O

Deep in the woods of Gravity Falls, lies the cave that Dipper read earlier in the journal. Outside the cave entrance, two small female figures, no more than a few inches tall, wearing red tribal garments look outside into the woods beyond, staring into the forested wilderness in deep thought.

"Can you feel it, sister?" Asked one of the women.

"Yes. Dark times are approaching soon." Responded the other woman. "They will soon be awoken."

"Are we prepared for the coming storm?" Asked the first women again. "We only know where it begins, but not when it ends."

"That I do not know, but I know that we must prevail in the end, or else." Responded the other woman.

"Or else, I win." Said a figure appearing from the forest brush.

The figure was not small but instead six feet tall and had a slim physique, he wore a fancy black suit with a black bowtie and a yellow blazer to match, he had a smooth complexion and was covering his right eye with an eye patch, he also wore a black top hat on his yellow hair and held a cane with a round shaft that had the eye of providence on it. As he walked over to the two women, he grinned gleefully as he took off his top hat and bowed.

"It's been a while, ladies." Said the slim figure, putting back his top hat as he kneeled down to their level.

"We wish that it was longer." Said the women at the same time, they would usually speak like this to others. "We wish it was never."

"Well, the universe can be cruel." Said the figure, grinning again in a more evil fashion. "And I know how cruel I can be, along with a few friends I know too."

"Why do you still want to do this, after all these years?" Asked the two women, not understanding the figure's purpose in all this. "What will you accomplish from these twisted games?"

"Aww, even after all these years, you two are still trying to play nice with me." Said the figure sarcastically, before breaking out in laughter. "Too bad I'm not so nice! HAHAHAHAHAHA!"

"Your games will be your demise." Said the women. "Nothing will be accomplished from them except your doom."

"Uh, news flash ladies, I played these games before and I never lost." Said the figure, confident in his abilities. "We may be mystical beings here, but there's no chosen ones or destiny involved in this, just whatever fun that's in store."

"But you are weak here." Said the women. "You may be powerful but only to an extent. You have limits like us."

"Sure, I can't use my powers here, but you can't either." Pointed out the figure. "And I don't need them anyways. Words are all I need."

"Then we shall use words like we always have." Said the women, giving the tall figure a spiteful look.

"And giant monsters." Said the figure happily. "That's always my favorite part."

The tall figure then knelt back up, ready to leave the two women to their duties. He turned around and walked a few steps back until stopping in place.

"Oh and uh, I have one more thing to give you two." Said the tall figure.

He then turned rapidly and swung his cane horizontally at the two women, hoping to hit the two in one precise hit, but as he looked to see the two women, they had disappeared from his sight, making the figure smile evilly as he walked away.

"Let the games begin."

O-O-O

Disclaimer: I do not own Gravity Falls or Godzilla… that makes me sad.