The Pines lay in a tangled pile at one end of the laboratory as the dust settled. They were blinded by centuries of dust, hot jets of steam and a strangely amphibious feeling atmosphere - everything seemed damp, swampy, and waylaid. Like the moisture of the earth was seeping through from the hillside. For a moment, they even wondered if the entire building had sprung a leak…

It was dark, the space lit only by the locomotive's headlight, mounted atop a fatally wrecked smokebox that belched vapour and the smoke generator's exhaust into the room. It was a choking, clagging sort of smoke that made them feel like they were being coated in a thin layer of oil.

McGucket really needed to get better fuel for that thing.

The entire thing had careened straight through the wall and was now sitting at an awkward angle, spitting hot vapour, water and the odd rivet in all directions. The thing was a write-off - much like the broken laboratory itself.

Dipper coughed and groaned, clutching his sister's hand. "Y-you okay Mabel?"

"No…" She huffed. "I think I swallowed my gum."

"No way, you had gum?!"

"Now I don't."

The young investigator grunted, stood to his feet and rubbed his head, wincing at the mess that surrounded them. Before his eyes had even fully opened, he spotted Pacifica, completely motionless to his eyes, sitting up against the wall of the laboratory. It was perhaps only via a well-placed miracle (or, he briefly wondered, a bit of physics contrivance courtesy of a giant space newt) that the wreckage and detritus had missed her.

"P-Pacifica! Nononono-" He ran to her, only to dodge out of the way of a metal pipe that fell to the floor between them, blocking his path. He tried desperately to clamber over, his soaking court-appointed 'smart shoes' (slightly less torn sneakers) slipping and sliding on the smooth surface. "You better wake up! You sure as hell better wake up or-"

Stan bolted over, lifting the heavy lump of iron. "Blondie! Ah, c-c'mon kid, don't do this!"

The pipe rolled out of the way under the old man's burly arms as he crouched down and lifted the Northwest heir, getting increasingly panicked. "I- I don't feel a pulse!"

"Not there, you idiot!" Ford rolled his eyes and checked her neck. Quite why Stan thought he'd get a pulse from her shoulder, he wasn't entirely sure. The scientist waited carefully, as if they weren't being surrounded by a smoking, collapsing chamber of death. "...She's fine. Probably just a bit dizzy."

Her eyes flickered open and she turned to face Dipper with a dozy smile. "Heh… Y-you're sorta cute…"

"Oh god, she's lost her mind!" Dipper winced.

Pacifica retorted by punching him in the arm. "Dummy…"

Ford laid the rather delirious Pacifica somewhere a little less prone to structural collapse. He tussled her hair and smiled as if she was his own griece. Great niece? The former didn't sound particularly appealing.

"S-she'll be okay?" Dipper asked, frantically.

"I- I'm fine." She said.

"Trust me, Dipper." Ford smiled. "I'm a doctor. Not a medical doctor, but I read textbooks for fun."

"I said I'm fine!" The Northwest heir barked, not particularly happy with being spoken around rather than to.

Then, they froze.

They heard movement. Footsteps. They prepared for Nathaniel Northwest's shambling body to reappear, arming themselves with just about everything they could find from their surroundings, in case they had to fight. Pipes, petrified notebooks, ice picks with strange red stains on their blades….1970s furry fanfiction? Gross.

They were all tensed and ready - only for a gangly silhouette to step through the illuminated hole in the wall, climbing coolly over the forty-ton wreckage, clutching a wrench.

"W-Wendy?"

"Damn… I hope McGucket is insured…" she muttered, only to be greeted by the ragtag group of ne'erdowells. "Man, I shoulda known you guys would have been up to something crazy."

"YOU WERE JUST IN A TRAIN WRECK!" Dan bellowed in a very genuine panic, running over to his daughter and squeezing her tight. "ARE YOU OKAY?!"

"I'm fine, Dad. Marcus is trying to scout for a way outta here. What's uh… What's with all the… Stuff?"

"Uh… it's a long story." Dipper winced. "Let's just say that uh-"

SPLAP

The slithering, multi-limbed, multi-faceted remains of Nathaniel Northwest fell to the floor and hissed at her, the enormous, writing mess seemingly having only grown…squishier following the wreck. Dipper figured that it had been pulverised or something.

"...Got it." Wendy said, blankly.

"Pines!" Quentin flew through the door, holding the Northwest's book. "I've found the route to sending Nathaniel back to the beastly, oak-laden chamber from which he came! The day is most definitely sav- why is there an iron horse here? And do I smell gunpowder?"

There was an awkward pause.

"Nope, no, I totally need an explanation here, dude." Wendy finally admitted, turning to Dipper.

"Let's just say that Nathaniel Northwest has been through a rough spot."

"Oh, sure." Pacifica snapped from her corner, clutching her head. " He's been rough a spot!"

The locomotive fell a further foot or two as it continued to settle amongst the rubble. Finally, with a crunch, a wooden beam gave out, the tank's filler cap opened and out came a few thousand gallons of the town's finest locomotive water. Which, in typical Gravity Falls fashion, had been siphoned from the lake.

It flew forward in a mini tidal wave, but didn't stick around for long. The interdimensional link was whirring away - and - before their eyes, every drop was sucked up into what appeared to be Cornelius Northwest's cavernous eye sockets. One minute the water was there, the next it was gone. Absorbed. Taken to territories unknown.

Of course, what made them fear the link so much was what had lurked on the other end, last time they were in the laboratory. They almost expected to hear the triangular menace's shrill laughter. The cackle of Cankerblight. Perhaps smell the scent of fennel.

But there was nothing. A smell of ozone. Almost a smell of…emptiness.

Whatever Nathaniel's remains had built - each component of which proudly carried 'WENTWORTH' imprinted on small brass plates - it was working. Working a little too well. Floorboards began to pop out of their mountings, the engine's headlamp flickered, and Mabel swallowed another piece of gum, as the gateway began to flex and bend reality around them. The borders between worlds hadn't been so thin since that terrible day last summer; the difference was this wasn't the nightmare realm. It was purgatory. And purgatory only had two creatures within.

It was as if the room was melting, bending, forming… twisting like a funhouse mirror that writhed and reflected in the bright light of the railroad lamp. Like the laboratory was folding and breathing and gyrating around them. They panicked, gripping brick walls, wailing, yelling in confusion as they were lifted into the air by the laboratory's turbulence…

Then it halted. Everybody was thrown to the floor.

Nathaniel let out a wheezing laugh. A throaty, gurgling, bubbling laugh that echoed from an indistinguishable throat, thick blue sputum and black mucus spilling over its purple lips, punctuated by drips of tar-like blood from the wound in its jaw…

A blurry patch seemed to develop ahead of them, like heat rising from the asphalt in summer. A hazy, bubbling effect that seemed to vibrate gently. Before their eyes, the very fabric of existence seemed to melt away like ice cream, revealing a deep, black hollow. No light seemed to escape it. No light seemed to enter it.

"We're too late," Quentin said. "We must go somewhere where no such partisan conflicts exist…Ireland."

"Quentin, what do you mean too late?" Ford asked, firmly.

"You know what a dimensional rift looks like, my man. This- thing of this as something similar. Not an uncontrolled tear, but a uniform…kitchen-hatch to another world."

"But the only guys at the other side are-"

"Oh my god." Stan interrupted them, his mouth agape, as the little hole began to leak…