Author's Notes: Sooooo, I know this isn't a new chapter of Learning Heroics. (Hangs head in shame for a sec) but I've had this idea for a while and then other people were getting the same idea and I had to get it out while I was still kinda sorta ahead of the curb. Also a very talented person on tumblr showed interest and I couldn't pass up the opportunity to impress them.

This is a Gravity Falls AU idea where Stanley is the one who goes through the portal, and Stanford is left behind. No idea how long it's gonna be.

Chapter 1: Newton's 3rd Law

With a shove, Stanford was airborne. The gravity anomalies had started. He was drifting towards the portal, out of control.

"Stanley! Stanley, help me!" Ford cried in a panic.

Stanley jumped up, grabbing his brother, but getting himself caught up in the gravity anomaly in the process. Ford knew in a millisecond that it was hopeless. The momentum of Stan's jump had only served to propel them towards the portal faster, and put a spin on their weightless motion. But then something happened that he hadn't expected. Stan pushed him away from the portal. Newton's Third Law dictated that an equal and opposite law pushed back on Stan.

Right into the portal.

"Stanford, wha'do I-" His brother's cry was cut off in a flash of light. An explosion rang out from the portal, throwing Ford to the ground. He got up almost immediately, whipping around to face the portal.

"Stanley…" He said hoarsely. He knew it was no good to call out. The portal had gone dark. "No… no, what have I done?" He whispered, voice shaking almost as badly as his body.

Stanley couldn't be gone, not like this! All those years Ford had been trying to bury the guilt of being the 'favorite child', the 'good son'. All those years holding a grudge over a moment of betrayal. He'd felt guilty about that too. Maybe things would have been different if he'd tried to talk some sense into his father that night. Or maybe that just would have gotten them both thrown out. Maybe that would have been better too.

Stanley was gone again, and it was Ford's fault.

He shot up from his self-pity. There was still hope, but the longer he waited, the slimmer the chances of Stan's survival. Ford ran to the controls, checking the settings at the time of the event. He wrote down the conditions and parameters exactly in the first volume of the journal. He'd have to find another way to hide it after he brought Stan back.

Recalibrating the position of the transdimensional vortex would take time. But first things first: he would have to get more fuel.

The warehouse where Ford stored extra fuel for the portal was, out of necessity, a long way from his house. It wasn't a good idea to keep radioactive waste close to where one slept. Not that Ford slept much anymore.

He was lucky to have Stan's car. Normally he'd have to hire someone to shuttle fuel for him. He was quite sure he couldn't pay anyone enough to transport toxic waste in this blizzard. Visibility was nil, and the winds were strong enough that he had trouble keeping the car going in a straight line.

By some miracle Ford reached the warehouse. He pulled the car up as close to the doors as he could. No need to spend any more time than necessary in that freezing wind. He briefly regretted setting so many locks on the door.

The inside of the building was as dark and cold as the outside, but at least the wind was gone. Ford grabbed a trolley, loaded on a few barrels of fuel, and wheeled it around to the door.

Only someone was standing in his way.

Ford felt his insides knot up. In his haste he'd forgotten his usual triple-check of the perimeter. Of course the one time he threw caution to the wind, he came to regret it in just a few minutes.

"We knew you'd have to come back here for more fuel sometime." The tall figure blocking the door said. He was draped in a long red robe, with an X-ed out eye emblazoned on the hood that covered his face.

"I don't have time for the Blind Eye tonight! Step aside!" Ford yelled with a bravado that masked his terror. They'd finally cornered him. He'd messed up and they'd finally cornered him at the worst possible time!

Three more robed figures stepped into the light pouring through the doorway. Had they been hiding here the whole time? How had they gotten in!?

The Society of the Blind Eye removed their hoods. To his left, Stanford saw a face he recognized. The trucker he'd payed to transport the last shipment.

"Great. This is why I don't trust people!" the cornered scientist muttered under his breath.

But wait. There should have been another face he recognized. Where was…

"Please Stanford, listen to reason." A shaky but familiar voice said behind him. Ford turned to see Fiddleford McGucket standing with a memory erasing device pointed straight at him. His old friend looked terrible. His hair was dishevaled, his face unshaven, and his eyes unfocused.

"Fiddleford, listen to me, I need-"

"No, you listen to me!" Fiddleford snapped suddenly, "That portal will spell the end for Gravity Falls, Oregon, the United States, the entire world! You need to forget about it!" the crazed engineer's voice softened. "You will feel so much better afterwards. No more nightmares, no more monsters."

"Fiddleford, I can't! Not now!" Stanford pleaded.

"Look at what it's doing to you Stanford!" McGucket cried. Ford took inventory of himself and found he didn't look any better than his old friend.

"I know! I know you were right about the portal, but I can't shut it down now! Not until Stan's safe!"

The members of the Blind Eye stared at him like he was speaking another language.

"It really has driven him mad." The tall man blocking the door said. "Sir, I say we take him now."

"Ivan, I don't-" Fiddleford started.

"He's proven in the past that he won't listen to reason. If what you say is true, it will only get more dangerous. We'll remove the memories, by force if we have to."

Ford didn't wait for them to mull it over. He knew where this was going. He had to get out of there, now. He swung a punch at Ivan, socking him right in the eye. The tall man gasped and held his face, but managed to stay standing, blocking Stanford's only exit. He wasn't about to let that stop him. Using the heavy trolley like a battering ram, Ford charged right over the cultist. The momentum of the trolley kept it going over the icy ground outside, until it barreled into the side of Stan's car. The force of the crash jolted Ford, causing him to slip on the ice as well.

When Ford tried to get up, he found a foot pinning him to the ground.

"I'm sorry I have to do this, Stanford." Fiddleford said grimly, leaning down to fire the device into Ford's face. Stanford didn't hesitate to lash out at him. All those years of boxing lessons hadn't been for nothing after all.

The two of them fought like wild dogs, both fueled by desperation. The fight finally stopped with a flash of light. Fiddleford stood up, while Ford lied on the cold wet ground, shaking.

"Better erase the Journals too, just to be safe." McGucket said, turning the dial on the memory device.

"No, please!" Ford yelled before another flash of light enveloped him. He trembled and curled into the fetal position, letting out a low moan.

"Take him home." Fiddleford ordered the members of the Blind Eye. "His mind should settle back down by morning."

As they tried to pick the grown man up out of the snow, Ford sat bolt up.

"Stanley! What did I- what did you do!?" He sobbed. "He-he's gone, and I don't know how… or… or why, but I know he's gone and I… I don't know… what can I do? What did you do!?"

They dragged him into the car and drove back to Stanford's house, trying their best not to let his crazed ramblings bother them

It was just something they'd have to forget later.

Stanford woke up with a start in Stan's car the next morning, cold and damp. His mind was groggy, but he knew something was very, very wrong.

Stanley! Stanley had come and something terrible had happened to him! Ford waited for his mind to wake up so he could put together his foggy memories and remember what happened. Only it didn't. The memories stayed foggy. If anything, they only got foggier. He looked around. The car was parked in front of his house. The door appeared to still be locked. Several footprints led away from the car and into the woods. What had happened last night!?

Ford's stomach knotted. What if Bill had… no, that was impossible, if Bill had possessed him then… then… what… what was Bill trying to do again?

Ford staggered out of the car and up the steps to the door, fumbling with the locks. This was disconcerting. Large chunks of his memory were missing. What could have done that? Whatever it was, he was certain it had to do with his brother's disappearance.

Had Stanley disappeared? He remembered asking Stan to come, heaven knows why, and sure enough, Stanley came. That much he remembered. But after that, it was all a blank. Stan's car was still here, maybe he was just out.

The pit of fear and guilt in Stanford's gut said otherwise. His twin was gone, and he'd had something to do with it.

Stanford walked through his house in a daze when he saw a leather-bound book laying on the floor, as if it had been dropped in a rush. He stared at it curiously. It had a golden outline of his hand on the cover, with a number 1 printed on it. How was that possible? Where had it come from?

And yet as he stared at it, it seemed familiar, almost like a childhood toy found in a forgotten corner of the attic. He opened the book and flipped through the worn, stained pages. It was definitely his handwriting. He stopped when he came to a picture of the bookcase in the den. It detailed some sort of hidden staircase to the basement. Stanford scratched his chin thoughtfully. Was this house even supposed to have a basement?

He followed the book's instructions, taking him past the bookcase, down some stairs and into an elevator, where he input more codes taking him further below the house. What he finally found was mind-boggling. A high-tech lab, filled with computers and monitoring equipment the likes of which he had never seen. It all seemed to be connected to some room on the other side of some large glass windows. When Ford was done admiring the lab, he looked into the other room

What he saw also seemed familiar, but more like a forgotten childhood terror than childhood toy. It was a giant inverted, obtuse triangle, with a large circle cut out of the middle. Four similar rings stood in front of it, two on the ground and two on the ceiling. Ford looked to the book and found a page that seemed to depict the bottom corner of the machine.

Although this is currently just a concept, I believe this portal schematic is feasible. If my research is correct, I could open a gateway into the next dimension and see the origin of these anomalies. This will take caution, of course. Not all the strangeness in Gravity Falls is friendly. I don't imagine the dimension they come from is any better.

Ford gulped. A portal. Was that it? Was that where Stanley had gone? Into this other dimension of weirdness? It seemed a bit of a leap in logic. This was a hidden lab, how would Stan have even gotten down here?

Then he noticed something. A burnt scrap of fabric lying to the side of the control console. Although it was badly damaged, Ford could still make out the color. A dirty, greasy red, like the coat Stan had been wearing.

Stanford looked around the lab. It had security redundancies upon redundancies. Obviously, whoever had built it, and Ford was growing more and more certain that it was he himself, did not want anyone tampering with it. It might take weeks just to get past those. He looked down at the book he held in his hand. Hastily written in the corner was what appeared to be settings for the portal. This book would be his key to working out how to use it.

He wouldn't let this guilt gnaw away at him forever. He'd bring his brother back, even if it took a lifetime.