Hello! Welcome to Mystery Gems, my accidental thought-run-wild Gravity Falls AU! I am a big fan of both Steven Universe and Gravity Falls, and this story is the mix of those loves. I hope you enjoy the concept as much as I do!

Please note that this story will mostly be to-script toward the beginning, and diverge further into its own general timeline as the story goes on. It will be essentially a full-series edit of Gravity Falls itself, with a bit of Steven Universe thrown in for good measure.

Essentially, the plotline is that the mystery twins are partial gems, like Steven from Steven Universe. Do enjoy it, and tell me what you think!

~Arg

Ah, summer break. A time for leisure, recreation, and taking it easy.

Unless you live in a monster-infested town with a Gem for a dad.

My name is Dipper Diopside Pines. My twin sister is Mabel Dioptase Pines. Right now, we're in the process of fleeing from a creature of unimaginable horror in a golf cart, Mabel's probably about to puke, and you're probably wondering how that all happened.

Rest assured, there is a perfectly logical explanation.

Let's rewind.

It all began when the monsters started invading our hometown. Our dad was one of the few people who could fight them, being a gem warrior and all. To get my sister and me out of danger, since we don't have any magic yet, our parents shipped us up north to a sleepy town called Gravity Falls, Oregon to stay at our great uncle's place in the woods.

"This attic is amazing!" Mabel shouted to me as she was putting up another creepy boyband poster. She turned to show me her hands, covered in bits of wood. "Check out all my splinters!"

I walked into the room, and was about to set my bag down when I heard a loud bleat. I whipped my head around to see the animal where it shouldn't be.

"And there's a goat on my bed."

The goat immediately took ahold of my sister's sweater sleeve as she approached, and started trying to eat it.

"Hey, friend!" she grinned at it. "Oh, yes, you can keep chewing on my sweater." She then giggled at the situation, as she often does.

My sister tended to look on the bright side of things. Rolling down hills, she only shouted, "Yay! Grass!" At the same time, I was trying to write in one of my personal journals as I was getting constantly annoyed by random animals deciding I was a tree or something. All in all, I was having a hard time getting used to our new surroundings. Especially since our great uncle, or "Grunkle," was finding more and more ways to pop out of nowhere and startle me.

Our Grunkle Stan transformed his house into a tourist trap he called 'The Mystery Shack.' The real mystery is why anyone ever comes to the place.

And guess who had to work there.

Grunkle Stan is a stingy boss, having us constantly do chores in the shop, not even letting us touch the merchandise.

It looked like it was going to be the same boring routine all summer. That is, until one fateful day…

"He's looking at it!" Mabel said excitedly, hiding behind the Stan bobbleheads. "He's looking at it!"

A boy was reading a note Mabel wrote. "I rigged it," she told me, bouncing and grinning.

I shook my head and sighed. "Mabel, I know you're going through your whole 'boy crazy' phase, but I think you're kind of overdoing it on the 'crazy' part."

"What?" Mabel asked, with a tone of disbelief, before she blew a raspberry. "Come on, Dipper. This is our first summer away from home! It's my big chance to have an epic summer romance!"

"Ignoring the fact that we were pushed here because our town is in danger, do you have to flirt with every guy you meet? There was the guy at the park, the guy you pushed into the postcard stand, the guy you met at the mattress store…"

"Mock all you want, brother, but I've got a good feeling about this summer. I wouldn't be surprised if the man of my dreams walked through that door right now."

Thank goodness Grunkle Stan walked in just then. I needed a good laugh.

"Alright, alright, look alive, people," Grunkle Stan called. "I need someone to hang up these signs in the spooky part of the forest." He held up the signs, looking first at us, and then at Wendy, who was at the cash register.

To be honest, I wasn't too keen on going out of the shack or getting too far from our Grunkle, considering that he was practically the only gem in a thirty mile radius. He had to know how to fight, right? We already knew that he used a couple of his abilities to trick his customers. I couldn't have said "Not it!" faster.

Unfortunately, neither could Mabel.

Soos, the repairman of the Mystery Shack, decided to pipe up then, lowering the tension in my mind a bit.

"Uh, also not it," he said simply, while fixing the lightbulb near the doors.

"Nobody asked you, Soos," Stan reminded the large man.

"I know," he replied, "and I'm comfortable with that."

Stan shook his head and turned to the cashier. "Wendy, I need you to put up these signs."

Not even looking up from her magazine, she opened her hand toward Stan and mocked trying to grab them. "I would," she said, faking struggling noises, still reading her magazine. "But I can't reach it."

"I'd fire you all if I could," Stan grumbled. He then pointed at each of us one at a time, pointing first at Wendy, then Soos, then Mabel, then me.

"Eeny, meenie, miney, you."

"Aw, what?" I grumbled. "Grunkle Stan, whenever I'm in those woods, I feel like I'm being watched!"

Grunkle Stan facepalmed. "Ugh, not this again."

"Not to mention how the monsters from back home could be here, too! I don't even have any magic! I don't even have a gem weapon!"

"Kid, every gem has magic and a weapon. Even if it's terrible, like a shield. I'm sure you'll get your weapons eventually. Anyway, the monsters are being taken care of by my nephew back in California. The entire state is safe."
"Well," I said, quickly trying to come up with a counter argument. "I'm telling you, something weird is going on in this town. Just today, my mosquito bites spelled out 'beware!'"

I showed him my mosquito bites, and he squinted at them.

"That says 'bewarb,'" he corrected. "Look, kid. the whole 'monsters in the forest' thing is just local legend, trumped up by guys like me to sell merch to guys like that."

He pointed at a large man, who was creepily giggling at a Stan bobblehead.

"So quit bein' so paranoid! There aren't any monsters needing defeating and bubbling, or any of that."

"Bubbling? Is that that thing that Dad does when he picks up the gemstones those monsters leave behind?"

Stan looked away. "...Maybe," he said, before he turned back to me. "Go post those signs, kid."

I sighed as he handed them to me.

It was there, in the spooky part of the forest, where I found it.

I was hammering the signs onto the trees when the second one made an odd metallic 'clang.'

Confused, I tapped gently on the trunk again with the hammer. More soft and metallic 'clangs.' There had to be something in the tree. It was obviously fake at this point.

Rubbing my hand against the trunk, I found a panel, and pulled it open. Inside was a small switchbox, and so I tried the first switch.

Nothing.

I tried the second, and heard a panel move behind me. Quickly, I turned to look, only to see a compartment in the ground opening up. I hurried over to it to peer inside. A book was in there, dusty and ratty. There was a hand on its cover, oddly six fingered, with a big number three on it. An eyeglass was hanging from one corner of the book. On its back was a sparkling, clear gem. I opened the book and started to read.

"'It's hard to believe it's been six years since I began studying the strange and wondrous secrets of Gravity Falls, Oregon.' What is all this?"

I found a page that said 'TRUST NO ONE' on it in large letters. To be honest, that wasn't very reassuring.

"'Unfortunately, my suspicions have been confirmed. I'm being watched. I must hide this book before he finds it. Remember: in Gravity Falls, there is no one you can trust.' No one you can trust…?"

"Hello!" Mabel yelped from behind me. I shouted in response. "What'cha readin? Some nerd thing?"

"Uh," I said, panicking. "Uh, it's nothing!"

"Uh, uh, it's nothing," she repeated, mocking me. "What, are you actually not gonna show me?"

I thought about that for a moment. "Uh, let's go somewhere more private."

"It's amazing," I said excitedly, talking to Mabel in the living room. "Grunkle stan said I was being paranoid, but according to this book, Gravity Falls has a secret dark side!"

"Whoa!" Mabel yelped, then pushed me. "Shut up!"

"And get this," I continued. "After a certain point, the pages just stop, like the guy who was writing it mysteriously disappeared!"

Just then, the doorbell rang. Confused, I looked in the direction of the door. "Who's that?" I asked.

"Well," Mabel said, dangling her feet over the couch arm. "Time to spill the beans!" She then knocked over an empty can labeled 'beans.' "Boop! Heheh… Beans. This girl's got a date! Woo-woo!" Then she fell onto the rest of the couch, onto her back.

"Let me get this straight… In the half an hour I was gone, you already found a boyfriend?"

"What can I say?" she grinned. "I guess I'm just," her tone became low and far from serious as she waved her sweater sleeves around, "IR-RE-ZIS-TABLE!"

The doorbell rang again, twice.

"Coming!" Mabel shouted, then ran out of the room. I decided to use this time to finish reading through the journal.

Stan chose just then to walk in and surprise me, making me hurry to switch the journal out with whatever book I could grab first.

"What'cha readin' there, Slick?" Grunkle Stan asked, sipping his soda.

"Oh, I was just catching up on uh…" I looked at the title of the magazine I was holding. "...Gold Chains for Old Men Magazine?"
"That's a good issue," Grunkle stan assured me.

"Hey, family," Mabel called from the doorway. Both Grunkle Stan and I turned to look at the gruesome figure standing next to my sister. "Say hello to my new boyfriend!"

"'Sup?" the guy asked, turning to face us.

"...Hey?" I replied, a little hesitant.

"How's it hangin'?" Stan joins in, more or less not caring.

"We met at the cemetery," Mabel informed us. "He's really deep." She then continued to feel the guy's arm. "Oh! Little muscle there…" she said quietly, maybe even nervously. "Heh heh… wh-what a surprise."

"So…" I began, a little skeptical of this guy. "What's your name?"

"Uh," the guy hurried to say, making my suspicion stronger. "Normal… man!"

"He means Norman," Mabel corrected.

I noticed a dripping, red spot on 'Norman's' face. "Are you bleeding, Norman?" I asked him. I saw his eyes dart to the side.

"It's jam," he said quickly. I heard Mabel gasp.

"I love jam! Look at this!" she grins excitedly, gesturing between Norman and herself.

"So you wanna go hold hands or… whatever?" Norman asked her. Well, at least she found someone who showed genuine interest this time.

"Oh," Mabel grinned, starting to blush. "Oh my goodness. Heheh…. Don't wait up!" she called to Stan and me, waving goodbye as she and Norman left, Norman smacking into the wall first. I think I heard something shatter on their way out.

There was something about Norman that wasn't right. I decided to consult the journal.

I moved to the attic with the journal and started flipping through pages.
"'Known for their pale skin and bad attitudes,'" I began reading aloud, "'these creatures are often mistaken for… teenagers!'" I knew this had to be it. "'Beware Gravity Falls' nefarious… Zombie!"

I looked out the window just then, only to see Norman limping slowly over to my sister.

"Oh no," I yelped. "Mabel! No, no, watch out!"

"Daisies?" Mabel grinned at Norman, as he put a flower necklace around her neck. "You scallywag."

"Is my sister really dating a zombie?" I asked myself. "...Or am I just going nuts?"

"It's a dilemma, to be sure," Soos said suddenly from behind me. I quickly whipped around to look at him. He was changing another lightbulb. "I couldn't help but overhear you talking aloud to yourself in this empty room."

"Soos," I said quickly. "You've seen Mabel's boyfriend. He's gotta be a zombie, right?"

"Hmm. How many brains did you see the guy eat?"

"Zero," I said, sighing in defeat.

"Look, dude," Soos whispered, leaning over to get closer to me. "I believe you. I'm always noticing weird stuff in this town. Like the mailman? Pretty sure he's a werewolf. But you gotta have evidence. Otherwise, people are gonna think you're a major league cuckoo clock."

"As always, Soos, you're right," I grumbled under my breath.

"My wisdom is both a blessing and a curse."

"SOOS!" Stan yelled from downstairs. "The portable toilets are clogged again!"

"I am needed elsewhere," Soos said grimly, before walking backwards out of the room. I'm not sure if I'll ever get used to the guy.

Anyway, my sister could be in trouble. It was time to get some evidence. I followed Norman and my sister anywhere I could with a video camera. There was a lot of stuff that was kind of zombie-ish, but no hard evidence. Eventually, I'd seen enough.

"Mabel, we've gotta talk about Norman," I told her seriously as I walked into our room.

"Isn't he the best?" she grinned. "Check out this giant smooch-mark he gave me!"

She then turned to show me a swollen cheek on her face. I cringed and yelped. She laughed.

"Haha! Gullible. It was just an accident with the leaf blower. That was fun."

"No, Mabel, listen! I'm trying to tell you that Norman is not what he seems!"

Mabel gasped somewhat theatrically and put a hand over her mouth. "You think he might be a vampire?" she asked excitedly. "That would be so awesome."

"Guess again, sister," I said, before accidentally showing her the page in the journal about gnomes. "Oh, wait. Uh, I'm sorry."

I quickly flipped to the page about the zombies and showed it to her.

"A zombie? That is not funny, Dipper," Mabel said with annoyance.

"I'm not joking!" I tried to assure her. "It all adds up! The bleeding, the limp… He never blinks! Have you noticed that?"

"Maybe he's blinking when you're blinking."

"Mabel, remember what the book said about Gravity Falls? Trust no one!"

"Well, what about me, huh?" Mabel asked, sounding offended. "Why can't you trust me?"

She then put on her star earrings, giving them little sound effects.

"Mabel, he's gonna eat your brain!" I warned. I didn't expect her to suddenly get angry.

"Dipper, you listen to me," she hissed, startling me, walking toward me menacingly, making me back up into the wall. "Norman and I are going on a date at five o'clock," she started poking me hard in the chest on beat with her words, "and I'm gonna be adorable and he's gonna be dreamy…."

"Wait, b-b-b-but, but, but…!" I stammered, trying to regain composure.

"...And I'm not gonna let you ruin it with one of your crazy conspiracies!"

Ouch.

With that, Mabel stomped out of the room, slamming the door behind her, leaving me both afraid for my sister and starting to feel the guilt come on. I sat down with a sigh. "What am I gonna do?" I asked myself sadly.

I watched from the window as I saw Mabel and Norman leave.

"Soos was right," I mumbled. "I don't have any real evidence. I guess I can be kind of paranoid sometimes, and-" I stopped as I saw Norman's hand fall off. I watched him discreetly put it back on. I yelped. "I was right! Oh my gosh!"

I started running downstairs and outside, where Grunkle Stan was trying to explain one of his novelty items or whatever to a large group of customers.

"Grunkle Stan!" I called. I kept calling. He continued to have a sort of argument with his audience. He'd be of no use. Thankfully, I saw Wendy drive over in the golf cart.

"Wendy! Wendy!" I yelled, running up to her. "I need to borrow the golf cart so I can save my sister from a zombie!"

Wendy stared at me for a second before dropping the key in my hands. "Try not to hit any pedestrians," she smiled, before walking away. Quickly, I got into the golf cart and started it up. Soos popped up behind me and handed me a bat.

"This is for the zombies," he told me, "and in case you see a piñata."

"Uh, thanks?" I answered, a bit confused. I then put the bat on the golf cart floor and started to drive as fast as I could toward where I had seen Mabel and Norman walk.

"Better safe than sorry!" Soos yelled after me.

"Don't worry, Mabel!" I yelled into the air. "I'll save you from that zombie!"

I heard her yell for help. "Hold on!" I shouted back, hoping desperately that she'd hear me.

I drove into a small, brightly colored area filled with tiny guys in conical hats and ridiculous beards. They were talking to Mabel, tying her down on the floor. "Let go of me!" I heard her shout angrily at them.

"What the heck is going on here?!" I shouted, as a little guy hissed at me before running away.

"Dipper!" Mabel yelled to me. "Norman turned out to be a bunch of gnomes, and they're total jerks!" A gnome started pulling her hair. "Ah! Hair! Hair! Hair!" she yelped in pain.

"Gnomes?" I said with confusion. "Huh. I was way off."

I pulled out the journal for some help, turning to the proper page. "'Gnomes; little men of the Gravity Falls forest. Weaknesses unknown.'"

When I lowered the book, Mabel was fully tied down. "Hey, hey let go of my sister!" I shouted at the gnome that seemed to be leading.

"Oh, haha, hey there!" the gnome laughed, looking up at me nervously. "Um, you know, this is all really just a big misunderstanding. You see, your sister's not in danger! She's just marrying all one thousand of us and becoming our gnome queen for all eternity! Isn't that right, honey?"

"You guys are butt faces!" Mabel screetched at him, before the other gnomes covered her mouth. I pulled out my bat.

"Give her back right now," I warned. "Or else."

"You think you can stop us, boy? You have no idea what we're capable of. The gnomes are a powerful race! Do not trifle with the-"

I didn't care to hear any more. I whacked the gnome with the bat, just hard enough to push him out of the way and bounce a couple feet.

I pulled away the string holding Mabel down, and she broke free of the rest of the gnomes. She took my hand, and we ran back to the golf cart.

I heard the gnomes shouting at us from behind.

"Seatbelt!" I reminded Mabel, as she put it on. I then backed out of the bright cavelike part of the forest.

"Hurry, before they come after us!" Mabel yelled. I scoffed.

"I wouldn't worry about it. Did you see their little legs? Those suckers are tiny."

My eyes widened as Mabel and I heard loud, huge footsteps from behind.

"Dang," Mabel whispered, as both of us looked up at the giant gnome made up of all the tiny gnomes we'd just escaped from. I stepped hard on the gas.

"It's getting closer!" Mabel shouts. I grit my teeth.

One of the gnomes grabs my face, blinding me. I try to smack him against the steering wheel, but it doesn't work. Instead, Mabel says something and punches him off of my face, making my hat go flying off too.

"Thanks, Mabel," I manage to say weakly, hearing my voice crack. Suddenly, I don't feel all that well. Am I motion sick or something? I feel nauseous. Like…. really nauseous.

"Don't mention it," she says somewhat fearfully. She then glances back at my face. "Uh… you okay?"

"I feel sick," I tell her honestly. I see her clench her teeth in the corner of my eye. The gnomes throw a tree in front of us, and I crash the cart into it. The two of us go flying, and I'm sure we're going to die at this point, so I close my eyes…

...Until I realize we're not falling anymore, and no pain came.

I open my eyes to find Mabel holding onto me, both of us dangling off the ground a few feet. I look up to see a glowing pink grappling hook with a shooting star design on it, and flakes of what seem to be crystals of dioptase.

"M-Mabel!" I whisper in awe. "Is that your gem weapon?"

"Grappling hook!" Mabel shouts. I smile. She lets us both drop to the ground, since we were at a safe falling height.

The gnomes inch closer as we look up at them fearfully. Out of the frying pan and into the fire.

"Stay back, man!" I shout. "Where's Grunkle Stan?"

"It's the end of the line, kids!" the leader of the gnomes yells angrily. "Mabel, marry us before we do something crazy!"

"There's gotta be a way out of this," I plea quietly.

"I gotta do it."

I look at Mabel with fear and surprise. "What? Mabel, don't do this! Are you crazy?"

"Trust me," she says seriously, looking straight into my eyes. The sick feeling gets worse.

"What?"

"Dipper," Mabel pleads. "Just this once! Trust me!" She then turns to the gnomes, looking straight up at the leader. "All right, Jeff. I'll marry you."

"Hot dog!" the gnome grins. He makes his way through the huge number of gnomes to get down to the ground. He then puts a ring on Mabel's finger. I admit that I eyed the crystals on the ring nervously.

"Bada-bing, bada-bam!" Jeff grins. "Now let's get you back into the forest, honey!"

"You may now kiss the bride," Mabel smiles, admiring the ring.

"Well, don't mind if I do," Jeff chuckles, turning to kiss Mabel, closing his eyes.

Mabel turns the leafblower on.

"Whoa! W-What's going on?!" the gnome shouts as he's pulled into the leafblower. I grin.

"That's for lying to me," Mabel screams, increasing the power. "That's for breaking my heart!"

"...And this is for messing with my brother!" She then turns to me, smiling a bit. "Want to do the honors?"

She points the leafblower at the giant gnome made of gnomes. I smile a bit, catching on.

"On three," I tell her.

"One, two, three!"

We flip the switch and Jeff goes flying, breaking the giant gnome formation.

"Anyone else want some?" Mabel asks, and the gnomes start scampering away.

"Hey, Dipper," Mabel says solemnly. "I, um… I'm sorry for ignoring your advice. You really were just looking out for me."

"Oh, don't be like that," I smiled at her, wrapping my arms around my stomach. "You saved our butts and got your gem weapon."

Mabel looks down at her grappling hook, which is still in her hand. She sighs. "I guess I'm just sad that my first boyfriend turned out to be a bunch of gnomes."

"Look on the bright side. Maybe the next one'll be a vampire."

"Yeah, right," Mabel grins.

"Awkward sibling hug?" I offer, despite my nausea, opening my arms in invitation.

"Awkward sibling hug," Mabel agrees, spreading her arms for the hug. We approach each other in synchronization, and hug for three seconds, before we both robotically chant, "pat, pat."

"Yeesh," Grunkle Stan grumbles as both of us walk inside. "You two get hit by a bus or somethin'? Hah!"

We ignore him.

"Uh, hey! W-wouldn't you know it, um, I accidentally overstocked some inventory. So, how's about each of you take one item from the gift shop? On the house, you know?"

"Really?" Mabel grins.

"What's the catch?" I ask.

"The catch is do it before I change my mind," Stan grumbles. "Now take something."

I grab a hat to replace the one that got knocked off in the gnome fight.

"I want the Cookie Cat fridge!" Mabel declares. Grunkle Stan rolls his eyes.

"Fine," he says. "The things got discontinued anyway. I'm not allowed to sell them anymore."

"Cookie Cats!" Mabel sings, grabbing the tiny freezer and rushing up to the attic with it.

"Mabel got her gem weapon today," I tell Grunkle Stan. He looks up at me with curiosity. "It's a grappling hook."

"Did you get yours, then?"

I shake my head.

"You look a little green, kid. You okay?"

"I don't know. I'm not feeling well," I answer.

"Well, just don't go ralphin' in the gift shop," he told me, then proceeded to count his money. I sighed and walked out of the shop to join Mabel in the attic. On my way there, I went into the bathroom and locked the door. I took off my new hat and pushed my bangs out of the way of my gem.

It had a tiny crack.

This journal told me there was no one in Gravity Falls I could trust, but when you battle a hundred gnomes side-by-side with someone, you realize that they've probably always got your back. Our uncle told us there was nothing strange about this town, but who knows what other secrets are waiting to be unlocked?

I guess we'll find out. I can only hope that I haven't already messed everything up.