As Alcor stepped through the hole in the space-time continuum, the dull monochrome scenery of the mindscape was replaced with a darkness tinged with deep blue, the thick walls and hard wooden floor of his beloved library now gone to reveal a nighttime sky studded with familiar constellations. A quick glance over his shoulder revealed that the portal which had brought him here had vanished, leaving nothing but stars and void in its wake.
He felt his connection to Mizar snap, and suddenly there was nothing but emptiness where she had been. She was lost to him now, lost as completely as if they had never met.
He was alone, and there was no turning back.
Alcor closed his eyes for a moment and took a deep breath to steady himself before scoping out his surroundings.
He knew the stars that surrounded him as well as he knew the back of his hand, but what grabbed the demon's attention was the forest below. As he floated downward, Alcor realized that he knew those trees, had walked beneath them and flown above them so often that they were practically ingrained in him, though it had been a while since he'd thought to visit.
Perhaps it was only right that these woods, and the sleepy town nestled within, would be in the center of things once more.
Gravity Falls…
Oh, it was good to be back.
Even if he hadn't traveled the path thousands of times over, Alcor would have been able to find his way to the Mystery Shack easily enough; on this dark night, the house filled the air around it with brilliant white light, the beam flickering on as the handful of other lights in the town dimmed. He would be hard-pressed to imagine a more perfect beacon.
Of course. Of all the nights that he could have ended up in Gravity Falls, it had to be this one, the one that would forever haunt the dark corners of his mind, the one that he would give anything not to have gone through once, let alone a second time around. The universe, it seemed, was going to continue taking every opportunity it could to mess with him. But was he here to prevent the pandemonium that was about to ensue, or to ensure that all went as it had in his own timeline?
Alcor zoomed through the walls of the Shack as easily as through the air, barely taking in his surroundings as he focused resolutely on his destination, desperate to reach the basement before it was too late.
The demon might have lost his mental link with Mizar, but maybe, just maybe, they could reconnect all the same.
But Mabel wasn't in the basement of the Mystery Shack, he found as he floated between its wooden beams. Neither was Grunkle Stan, or his past self, or even Bill.
But the two figures within it were familiar to him nonetheless, faces recognizable even as he noted how their features differed from those in his memories.
And the voice that called out into the abyss was one he had heard before, long ago, one he had nearly forgotten.
"When gravity falls and earth becomes sky, beware the beast with just one eye!"
He'd heard that prophecy before, albeit second-hand, from the man who now interrogated the one who had proclaimed it. Alcor knew how this story went, could remember the exact words that his great-uncle Ford had used to describe this scene, could guess what had remained unsaid.
It may not have been the one he had expected, but he had been dropped into the middle of a fateful night all the same.
Fiddleford stomped off, and Alcor couldn't help but think of what would come next for him- the secret society, the insanity, regret piled upon regret- how the one he knew as Old Man McGucket could have been wildly successful if he had ignored Stanford's request for assistance…
One fork in the road. That's all it took. One fork in the road, and he'd gone from wealth to ruin, from genius to madness.
"Fine! I'll do it without you! I don't need you! I don't need anyone!" Ford's words echoed through the cavernous space of the basement lab.
"Yeah, that's gonna work out just great." Alcor muttered.
Stanford turned around to face Alcor's direction, though his gaze was a few feet off the mark. "What? Who said that?"
The demon froze. He wasn't corporeal, was he? No, he shouldn't be… And Ford wasn't even looking at him, so that was right out. But he was the only one speaking in the room, unless…
Great-uncle Ford had never quite owned up to it, but Alcor had always had a sneaking suspicion about who had turned up to "help" after McGucket quit the portal project. He couldn't see or hear the suspect, though Ford had evidently done the latter, and it would only make sense that he could appear to some but not others, much as Alcor himself could be seen by Mizar when others remained blissfully unaware of his presence.
Alcor had vanquished him, of course, had banished him from existence for a good long time… but not in this timeline.
Not yet, anyway.
So he stood still, not blinking, not so much as moving a finger, just waiting for Bill Cipher to reveal himself.
A moment passed, then another.
There was no sign of Bill that he could perceive. If the triangle demon was present, he did not want himself to be known, at least not to anybody but Stanford.
Ford's glasses began to switch between two different pairs, though the man didn't seem to notice the discrepancy, continuing to glance across the room, his eyes never settling on one particular point.
That didn't seem like something Bill would do. Chaos and randomness was his thing, yes, but not on such a small, meaningless scale, and why would he mess with Ford at such a critical moment?
The symbols on the wheel surrounding the portal began to flicker between the arcane sigils that had been present before and a series of pictograms that Alcor knew all too well.
This wasn't Bill, he realized.
This was the time paradox.
For whatever reason, Bill must have found a plaything more interesting than a stodgy scientist in a backwards town in Oregon, or been caught up in activities that held a more straightforward reward- Alcor could guess what would appeal to Bill in such a manner, had been enticed by many of the same things over the years.
And Bill's absence was breaking down the time stream. Somebody needed to make Stanford realize how dangerous the portal was, so that events could unfold as they always had- the fight, the Mystery Shack, the Transcendence… Somebody needed to step in.
And there was only one candidate able, if not entirely willing, to step up to the plate.
Alcor shuddered before taking the shape of a yellow, one-eyed triangle and turning corporeal.
The portal symbols reverted to their previous state.
Ford's glasses settled on one look.
This was how it was supposed to be.
This was how it had to be.
"What- who are you?" Stanford called out, his gaze finally settling on Alcor's location.
Dipper Pines, Alcor did not say.
Your great-nephew, Alcor did not say.
"The name's Bill Cipher." Alcor said, floating downward until he was roughly eye to eye with Stanford. He changed his voice so it approximated that of the triangle demon, though it still sounded a bit off to his ears.
But, truth be told, he was very much okay with his impersonation of Bill Cipher being an imperfect one.
"And what kind of being are you?" Alcor could see the wheels in Stanford's head turning as he flipped open one of his journals, pen in hand, ready to jot down every bit of information that he could gather about the being in front of him. "A spirit? A shapeshifter?"
"Don't worry about the specifics right now. Just know that I'm here to help you out." Alcor had said similar words many times in attempts to convince somebody to make a deal. That's how he had to think of it. Just acting as the tempter, like he had before. Just reprising the role that he'd played so often in the past… future… whatever. He didn't need to think about the details. Details were irrelevant.
"I don't need help." Stanford glared with fiery eyes at the floating demon.
"Really." He glanced around the room, gaze lingering on the notes left incomplete, the crash dummy splayed out on the ground. "Could've fooled me."
"What do you want, anyway?"
"I just want to give you a hand." Alcor snapped his fingers, and a skeleton hand appeared in the air next to Stanford, who flinched as it came closer. "Get it? A hand?" The demon couldn't help but laugh at his own pun as he snapped his fingers again, banishing the bony hand into the emptiness from which it had come. "No, but seriously, I need this portal working as much as you do. If you give me a chance, we could be the perfect team!"
"Really?" Stanford's eyes narrowed. "And how can I trust you?"
"You can't." Alcor struggled to find the words that Bill would use to express his cold-hearted sentiments. "Trust is an illusion you humans use to delude yourselves into thinking you understand each other. But I can give you a few hints for free before we really start on all this, if that'd make you feel better. And we've got the same goal, after all. What would I even get from double-crossing you?"
It was a rhetorical question, of course, but it got Alcor thinking. What did Bill get out of scaring Ford into ending the portal project? Why didn't he just start up the Transcendence thirty years earlier, before any real resistance could be mounted? He searched his mind for the answers, but they eluded his grasp.
"I…" Stanford's eyes wandered, looking at the portal, the journals, the desk at which Fiddleford had used to work, before finally gazing back up at the demon. "I'm not so sure about all this. Can I think on it first?"
Oh thank goodness. It was one thing making small talk with Ford while acting like Bill, setting the stage for the other demon's later appearance; it was another thing altogether to actually follow through with Bill's evil plan, to cause heartbreak and anguish and nearly destroy the world in the process…
"Sure thing, poindexter! Take all the time you need! Just let me know when you're ready to work something out, and I'll be there in a jiffy!"
And with that, the demon retreated into the mindscape, leaving his great-uncle alone with his thoughts.
Alcor reverted to his twelve-year-old form and curled up into the tightest ball that he could, arms clutching his knees, as golden tears dripped down his face.
It had been so easy.
All it had taken was one little push, and he'd taken on the shape, the voice, the mannerisms of the one who was the epitome of everything he swore he'd never become- and it was, he thought, a practically flawless impression.
But it would do the trick. Because if Bill hadn't noticed the goings-on of Gravity Falls already, well, he certainly would now. He couldn't very well ignore an impostor in his midst- Alcor knew that if the situation had been reversed, if he had been the one faced with some fledgling taking on his name and persona, it would be downright infuriating. Allowing such things to go on uninterrupted would be unthinkable.
The impersonator would have to be silenced.
And there was only one sure means of ensuring that silence.
Alcor's tears abated, replaced with a deep shivering that encompassed his whole body.
Was this what the universe had brought him here for?
He'd killed Bill before, ensured that that monster would no longer wreak chaos in this realm… and now, it seemed, Bill was about to return the favor.
And it might be sooner rather than later, for all he knew. Alcor had to make sure that the other demon wouldn't catch him off guard.
A stray thought banished the tears from his face and clothes, and he stood up, back straightened. The demon closed his eyes for a moment, and he transformed out of his young, weak, human form into a humanoid shape covered in darkness, a void where color had been, save for a few golden lines snaking around his body- lines that, he belatedly realized, were uncannily similar to the bricks that filled the form of his nemesis.
"Bill, I-"
Alcor paused, gathering together all his strength- depleted in recent days, true, but still greater by far than that of most demons- and rethinking his words. He could do better than that, stronger than that, present himself as a worthy foe rather than a scared child.
Maybe he was going to die here, but that didn't mean Alcor was going to go down without a fight.
"B̙̖͎̯͎̱̰͗̒ͬ̆̚I̩͇̦̻̙̹͋ͧ͠L͚̘̰̘̯ͅͅL̦͎͕͗͑ͦ̐ͅ ̴̗̮̜̗̬̖͂C̣̟̬̖̮̭̓̈̈́͂ͤI̍P̫͙̩͜H̯͙̗̺̙͉̥E̝ͬR͚͈̪̥̎̀̍̃̉̇̆! I know you can hear me, you͡ m͜o̸n̨s͠te̵r͜! And I challenge you to a fight to the d̸e͝ath͏, demon on demon!" Bile rose into his throat as he voiced those last words. It was true, though. He was Bill's equal now, regardless of who he had been centuries ago. He was a demon just the same.
After a few seconds of silence, Alcor added, "Don't avoid me, you còw̴a̡rd͢! Let's get this over with!"
The demon's words rang out through the empty space around him, the cry echoing back in a faded, warped imitation of itself after traversing the breadth and width of the mindscape.