I noticed that there was only one Gravity Falls/Supernatural crossover on this site, and I decided that was an outrage. So I spent two weeks writing this, keeping in mind the hope that perhaps one day it could become a legitimate episode of Gravity Falls. I would love so much for a legit crossover to happen. Though I don't know how difficult it would be for Alex Hirsch to contact the CW and get rights to include Sam and Dean in an episode and also possibly get Jared and Jensen to voice-act for it. Either way, it would be so amazing to have this turned into an hour-long special.

As said, this is a crossover, and so I obviously wouldn't recommend reading unless you're very familiar with at least Supernatural (since the story does tend to focus more on Sam and Dean). I tried to structure this like a Supernatural episode, though I also tried to not include too many innuendos or swearing in the dialogue in order to make it more likely to be able to transcribe to a Gravity Falls episode. Also, I split it up into chapters so there would be easy stopping points for convenience.

Anyway, I hope you enjoy reading this as much as I enjoyed writing it!

It had been a boring week for Sam and Dean so far, not hearing of so much as a vague sign of supernatural activity. That sort of thing just happened sometimes—so they'd spent the last few hours driving through mountain and forest country, hoping that they'd have some luck finding a monster attack in the woods up here. So far today, there still wasn't anything in any of the local newspapers about mysterious hiking deaths or disappearances into the woods or anything of the sort. Dean hated to admit it, especially considering lives would have been at stake, but he was disappointed that there was nothing for him to kill.

"We've just got to keep moving north," Sam assured him, noticing how restless his brother seemed to be getting as he drove. "There's always something up in these foresty parts."

Dean acknowledged him with a grunt and went on driving, looking hopefully out the window every few minutes to see if he could catch a glimpse of anything in the tall trees on either side of them. When there was nothing, he supposed he hadn't expected anything to be near the road, anyway.

He half-considered just setting up somewhere and hunting for whatever might be in the area—except they never did that, and even their dad had told them not to, since it would have just been stupid. They waited for something to happen so they could figure out what they were going after without having to put themselves in danger first. That's how it had always been, and they weren't going to change the rules just because things were getting a little boring.

After about half an hour, they saw a roadsign for the nearest city, Culver, in ten miles. Population less than two-thousand. That gave Dean some hope, since it always seemed to be the smaller towns that had some creature eating people in the outskirts. When they drove into town, he turned into the parking lot of the first diner they saw.

"Let's stop here for a bite and see if we can find anything in the local news," he said, getting out of the Impala and shutting the door loudly. "Or at least anything in the freaking state of Oregon."

Sam smirked at Dean's frustration and grabbed his laptop to take into the diner. He hoped they had wifi. Then again, they always did.

It wasn't quite noon yet, so there was still time to order one of the breakfast sandwiches, which put Dean in an uplifting mood already. Once they ordered their food, Sam went searching away on his laptop.

By the time the food came back to them, he still couldn't find any freaky accidents or murders or reports of animals doing things they shouldn't. Pushing his laptop away with a sigh, Sam ate his egg sandwich and glanced over to Dean, who frowned down at his before picking it up to take a bite.

He smirked slightly at how childishly disappointed his brother seemed to be, and then his eyes darted over to a flyer that was taped to the window next to their booth.

"Hey dude, look at this," he said, and Dean followed Sam's eyes to the window. After reading it for a second, he reached up and pulled it off, then flattened it down on the table so it was easier for both of them to read it. The two brothers leaned in, the older one reading it out in a mock-fantastical voice:

"'Come visit Gravity Falls, home of the Mystery Shack, where you'll find all things supernatural. Find your own mysteries all over town and in the famed Gravity Falls forest and discover the town's rich history in the Gravity Falls Museum.'" Below was a picture of the town from a distance, and next to that was—"'Other places of interest: Lake Gravity Falls, the Tent of Telepathy (meet a real psychic!), and Greasy's Diner, home of the best burgers in the county.' I dunno, man, sounds like just a cheesy summer tourist trap to me."

"Well, yeah, but it couldn't hurt to go check it out," Sam shrugged. "We've had cases at places that just seemed like fake tourist stuff before—besides, if there's nothing, maybe we can just enjoy our time off. Maybe there just isn't much supernatural going on and we have time to ourselves to just go to a stupid tourist town and have a little fun, you know?"

"Hm," Dean responded in a grunt while he read the bottom of the flyer and drew his eyes across the small map. Left off U.S. Highway 26. Tourist buses available. "Well, it's pretty close from here. Probably only an hour-or-so drive. Hell, we've driven way further for less." Sam looked at him hopefully for another couple seconds before Dean said, "Alright, fine. Finish up your breakfast-lunch and then we'll get going."

What with all the signs, Gravity Falls wasn't hard to find, despite the town having mountains and woodland on three sides. As they drove into town, a lot of people turned to stare, likely because of the Impala. It being a tourist town, they probably didn't get many new people who weren't in tourist buses—not to mention that the Impala was a pretty freaking cool car. Dean smirked, proud of himself.

One of the first things they passed was a huge cabin-sort of building that looked pretty tourist-y. The door was open and the inside, from what they could see, looked like a gift shop.

"The Mystery Hack," Sam read, a bit of a sarcastic laugh in his voice.

"It's probably supposed to be the Mystery Shack," Dean supplied, noticing the spot where the S was missing.

Sam shot him a look. "No shit, Sherlock." Looking back over at the place, he said, "So, you wanna go in and check it out?"

"Nah, let's save it. The 'hack' part is probably true, anyway."

So they drove on through the neighborhood until they got to the middle of the town, where the library, museum, arcade, and several other places were at. Noticing the diner, Dean decided it was a good place to park. Now that they were close, they noticed that the place was built to look like a huge log, and that right under the main sign was the slogan: We have food. At that, they looked at each other uncertainly but opened the car doors anyway.

"Come on, maybe we can get some freaky stories from the locals or something."

Inside were few teenagers in one of the booths, two truckers in another, and a businessman at one end of the bar. Sam and Dean looked around, both thinking that they should really clean up the place better, as they went to the front and sat in adjacent barstools.

Since it usually seemed to be that way, Dean expected a hot diner girl to serve them, but instead, a woman who had blue hair done up in a sort of beehive and only one of her eyes open came out from the back room with a notepad in her hand and a smile, ready to serve them. Immediately put off by her appearance, Dean glanced to Sam with an almost horrified expression but otherwise tried not to show his surprise or act rude. The woman's eye seemed to light up at the sight of them, at which they got the distinct impression that she found them very attractive. In a creepy old woman-way.

"Well hi, I haven't seen you boys around here—but then again we get a lot of tourists," she said friendily, leaning on the other side of the bar. The brothers instinctively scooted a away a little. "Are you on a honeymoon trip?"

The question wasn't surprising, and normally one of them would have automatically corrected that they were brothers, but with a single look to each other, they silently agreed that it was better to pretend they were together so this woman wouldn't flirt with them. So they smiled and nodded.

"Oh, how nice! Mazel tov. Well anyway, everyone calls me Lazy Susan. What can I get you boys?"

Glancing up at the menu on the wall above the bar, Dean said, "A regular cheeseburger with pickled chips. And… a medium root beer."

"Nothing for me, thanks," Sam said when she scribbled down Dean's order and glanced to him, and when she left to the kitchen, he looked over at his brother. "You just ate an hour ago."

"Yeah, well, I wanted to see if this place lived up to having the 'best burgers in the county.' 'Sides, I'm still hungry." Sam smirked in amusement and a few seconds later, Dean muttered, "She had a really annoying voice, didn't she?"

"Oh man, I know," agreed Sam, briefly stretching out his lips into his Nope-face. "And I can guess why they call her 'Lazy Susan'…. That eye was creepy as Hell."

Dean could only agree with an eyebrow raise when the woman returned with a plate of food to deliver to the business man and then winked at them as she returned once again to the kitchen.

When she finally had their food, they didn't hesitate to try to start up a conversation that might help them.

"So, we've heard a lot about this town," Dean started before he even touched his burger, "is any of it true? Any of that supernatural stuff, I mean."

"Well, we got all sorts of legends, like the gobblewonker in the lake, but I've never seen anything myself, so I can't tell you much, hon. But the whole town swears up and down that that old convenience store Dusk 2 Dawn is haunted—it got abandoned and shut down years ago after the couple that ran it were murdered. Ever since, anyone who's gone in there has disappeared."

Sam and Dean looked at each other, and through another silent exchange they agreed to go check it out later. There was a moment of silence before the former said, "Um—we might be staying in town a few days, so is there anything else you think we should know about Gravity Falls, Lazy Susan?"

Thinking about it a moment, she said, "Be careful of Old Man McGucket—he's the town kook, and he might be a little dangerous. Oh, and if you're looking for a place to stay, there's a motel down the road!"

"Thank you very much," Sam said on instinct, and Dean internally scoffed at his brother's politeness.

"No problem, sweetie!"

Sam decided to do a little research on Gravity Falls on his laptop while Dean ate, but he couldn't find anything supernatural but a few reported sightings of bigfoot. And he didn't take those seriously, since just about every town with a forested area had those. There were, however, reports of disappearances that matched up with the convenience store story. He closed his laptop just as Dean was wiping the grease from the burger off his mouth.

"That burger was a lie," he said immediately, frowning as he pulled a five out of his wallet and set it down next to their food. "If that was the best in the county, we're not eating anymore burgers until we're out of Oregon. The pickled chips weren't too bad, though."

"Figured. You wanna leave, then?"

"Sure—wait, what's that over there?" He pointed to the machine at the far right end of the diner, and he and Sam got up to go see what it was. "Test your manliness, win free pancakes. Ha—dude, we should do it. I bet I'm manlier than you."

Rather than giving Dean the You may be older than me but you're such a five year-old look, Sam simply frowned and said, "No way, man—I'll beat you, easy."

Squinting his eyes in defiance, Dean pulled out two quarters from his pocket and inserted them. He looked away from Sam and shook his arms for a moment to ready himself, then gripped the handle and squeezed as hard as he could.

Oh man, that thing was difficult. All that muscle he'd built up from fighting monsters seemed to only be good enough for the third bar: Barely Passable.

"Oh, tough luck," Sam mock-consoled, grinning at Dean's butthurt face. "My turn."

He put in two more quarters and did the same, and not nearly as much strain showed on Sam's face as he squeezed the handle, though his arm muscles were very distinctly straining, and—within about ten seconds, the bars lit up all the way to the top. Manly Man.

The few that were in the diner clapped, and Sam's smirk was extremely smug. He denied the free pancakes, though, and continued to smirk at Dean's frustration on the way out the door and to the car.

"That doesn't prove anything," grumbled the older brother, making a mental note to work out more.

After checking into the motel (which was cleaner than expected) with fake credit cards, Sam and Dean took off in the Impala once more to find the convenience store Lazy Susan had told them about.

"That woman wasn't lying," Sam started as they pulled up to the store, careful to drive around the back so no one caught them. "In the past fifteen years, there's been about twelve disappearances from teenagers reported having planned to go into Dusk 2 Dawn beforehand. The murder reports of the old couple I found were pretty vague, though. Like the police didn't really have any proof but instead were just shoehorning it with fake details."

"Nothing we haven't faced before," Dean grunted, shutting the door of the Impala with a loud thud and walking around to the trunk to find his weapon of choice. "Vengeful spirits, small town, incompetent cops…. Just like old times. It'll be nice to deal with something easy for a change."

Pulling out a flashlight, he turned it on and stuck it in between his teeth while he loaded salt rounds into a shotgun and waited for his brother to do this same. It wasn't exactly dark, but they expected it to be dim in the abandoned store. With one look at each other, they acknowledged that they were ready with a sharp nod and shut the trunk together.

It wasn't at all difficult to pick the lock in the back door, as usual, but what did surprise them was that the light actually turned on when Dean flipped the switch. Usually that was just a "just in case" thing, but it never worked.

"How is the electricity in this place still running?" Sam asked warily, hesitating to turn his flashlight off and readying his gun in suspicion.

"I dunno, man—woah, look at this…." Dean kept his gun ready as he walked carefully over to the ice freezer and laid a hand on it. "Holy crap, it's still cold. How long ago was this place abandoned, again?"

"About twenty years ago," said Sam, curiously feeling the freezer himself. "There's no way the city's been paying for the electricity in this place themselves—it's got to be something supernatural keeping this place together."

Looking around a little more for a few seconds, the taller brother pulled an EMF detector out of his pocket and turned it on.

"Holy—"

It went crazy at once and without any warning, which could only mean the ghosts they were dealing with were pretty powerful spirits.

"I would say that the EMF's going nuts, but that would be an understatement."

"Dude, that thing's off the reservation," Dean said before taking a stance and spinning around strategically to see if he could catch sight of any movement. There was nothing, surprisingly, behind him (since a lot of these things tended to be melodramatic), but when he went into the next aisle, several bags of candy were knocked over.

And then it turned out to just be Sam and his huge frame knocking into the shelf, but it turned abnormal when they both heard an icy voice say, "Clean that up."

Not so much scared as confused, they looked to each other with raised eyebrows and silently agreed to do what the spirit said. When they placed everything back on the shelf, they continued through the aisles to no avail before they reached the tape lines of where their bodies must have been when they died.

"Check around the register—if they were murdered, they probably got shot over here or something, so maybe we'll find some ectoplasm," Sam advised, and Dean nodded.

Just like his brother said, there was black goo on the edge of the counter. There was no doubt that this was a haunting, now. "So what do we—"

Cutting him off was his cellphone, which rang with one of those default ringtones. At first he wondered who the hell would be calling him, but then he remembered the moment before he checked it—it wasn't a call, but an alarm he'd set.

"Crap, I'm missing the new episode of Dr. Sexy," he huffed. Sam barely had time to give him a look before the lights flickered and there was an extremely evident breeze in the store, and in the next second the windows were frozen over.

Right before their eyes, a message was being written in the frost as though by someone's finger: How old are you?

That was a lot less cryptic than they expected. The lack of danger in this case was really throwing them off.

Looking confusedly up at the ceiling, Dean hesitated and said clearly, "Thirty-three…?"

Sam cleared his throat. "Twenty-nine."

And just like that, the frost from the windows melted and everything was back to normal, leaving the brothers feeling awkward and still confused. Eyes still wide, they turned around, expecting something else. But there was still nothing.

When they turned their heads around again, the window was frosted over just enough for them to read the word "GO" written in it before melting once again. While they obviously weren't afraid of spirits, they figured there was just nothing else to do here. The ghosts weren't even going to try to harm them—they just wanted them to go away.

"That was… strange," was the first thing Sam had to say as they made their way back to the Impala. "Even for us."

Dean waited until he'd put away the gun in the compartment under the trunk before replying. "What kind of ghost wants ASL? And if everyone else who's gone in there has disappeared, then why were we not even attacked?"

"Well…." Sam leaned with both hands on the trunk of the Impala, thinking. "Everything frosted over right after your phone rang. And then they asked for our age, and when we answered, they stopped. Maybe they attack based on age?"

"Yeah, maybe…. Didn't you say everyone who'd disappeared were teenagers?"

"Yeah, but usually teenagers are the only ones stupid enough to go into supposedly haunted places, so that doesn't really mean anything on its own… but it's probably right, now that we know more."

"So, what are you thinkin'? Old couple gets killed by teenagers, forever hates teenagers in the afterlife?"

"I guess, assuming they were even murdered. But regardless of their motives, we're going to torch their bones anyway—they're dangerous spirits who need to be put to rest in any case."

It was probably one of the easiest hauntings they'd ever stopped. That night when it was the least likely for them to get caught, they took the routine trip of leaving the motel and driving to the local cemetery, pulling shovels out from the trunk, and heading out. It wasn't even difficult to find the graves of Ruth and Joseph Winchell (though everyone called them Ma and Pa for some reason, as even said on their tombstones), and after that everything was just the busywork of digging up graves.

"I kind of actually wish this had been more of a challenge," Dean admitted as he sprinkled salt over the two skeletons in the double casket. "Sure, easy is less risk, but to hunters, this is child's play, man."

"Careful what you wish for," said Sam, simultaneously pouring the lighter fluid over them.

Just as he lit the match, the spectral figures of two somewhat overweight old people appeared to be heading for them from a short distance. What with how easy this had all been so far, Dean was slightly shocked, but not enough to neglect to aim salt rounds at the both of them. He slowed them down just long enough for Sam to throw down the match and let the bones go up in flames. The ghosts appeared again just to show them deteriorating and being burned away from worldly existence, which told them there wasn't any particular object keeping them attached.

"Easy as pie," said Dean, and for the first time in a long time unsarcastically. "Speaking of pie, we should see if there's any other all-night convenience stores in this town and get some."

Sam was surprised his brother hadn't outright suggested they go back to Dusk 2 Dawn and see if any of the pie there was still good. And pie or no pie, they were both glad for a worry-free eight hours of sleep.

I just want to note that the Manliness Tester scene was one of my favorites to write.