Glen and Sans raced through the UNDR-Ground, drawing more than a few curious looks from humans and monsters alike. There was no question of using a shortcut; it was in a shortcut that Sans and Glen first encountered the strange black skeleton, and while the idea still seemed wild to Sans, he couldn't shake the feeling that his dark doppleganger had somehow sabotaged the shortcut somehow.
They reached the surface in record time, only to rush through the urban parts of the city. Sans levitated over traffic, Glen following by leaping over the cars with her Tek-boots despite honks of protest from the cars whose roofs on which she landed. They didn't talk; that would simply be a waste of time they already may not have.
There were three Grillbys in the Ebott area; the first was in Snowden, where it had been since the time the time of the barrier. The second was in the urban part of Ebott, and was a massive restaurant capable of seating over a hundred people. The third was in the suburbs of Ebott, and was more of a diner, much as the original Grillby's, though larger to accommodate both humans and monsters. Grillby (at least the one from the ichor-infested universe) lived in a renovated old house directly behind the restaurant proper along with his daughter.
Sans narrowly beat Glen to the slightly ajar front door before coming to a halt. He glanced at Glen, who nodded and immediately crouched down and moved quickly around the side of the house. Nodding more to himself than anything, Sans pushed the door open and stepped inside the Grillby Household.
It was a fine old home, once home to some rich aristocrat who kept it as a vacation home before a sudden financial loss caused him to abandon the home. Grillby and Fuku had done a good job cleaning up the place, though they were still in the process of painting it. The whole house was permeated with the scent of cinnamon with just an edge burnt wood, both normal smells around fire elementals. Normally, the smell brought Sans some comfort, but he only felt tense as he stepped around the empty cans in the half-painted hallways and approached the kitchen.
He slowly approached the ajar door and peered through the crack only to see Grillby tied to a chair by the strange blue threads in the center of the room. Sans slowly pulled the door open to see the small forms of Frisk and Asriel tied and gagged as well. Both of the children kicked and struggled, watched by the helpless eyes of a bound and gagged Toriel lying on the floor of the kitchen beside Fuku.
Fuku's eyes widened as they darted to Sans, making him fight the urge to rush into the room. There was no questioning that it was a trap, especially seeing as ErrorSans sent a picture. It didn't matter, however; seeing his friends captured like that wasn't something he could just walk away from.
"All right." Sans said, stepping into the kitchen. "I know you're here, you know I know you're here, so why don't you just cut to the chase and tell me about the bone you have to pick with me?"
There was no response. Most of those captured tried to speak through their gags to no avail. Sans took another step toward Fuku, this time saying, "If you think you're gonna catch me off-guard, you're way off. The only way this could be a more obvious trap is if you'd written in on the diner sign."
Still there was no response. Shrugging, Sans approached Fuku and crouched by her side.
"Are you okay?" he asked, reaching out to caress her cheek even as his other hand worked at untying her bonds.
Just as she nodded, Sans felt the familiar pull of a large amount of magic in the local area shifting. He didn't even look around as he moved his hand from Fuku's cheek to the direction of the magical source, the Gaster Blaster forming in a fraction of a second and firing a blast of blue energy at the black skeleton who had just appeared in the doorway behind Sans. The blast knocked the front door clear off its hinges and sent it flying across the street. As the light faded, however, there was no sign of Error.
"Something tells me that was way too easy." Sans said, eyes darting around for some indication of where his darker self was.
A blue thread snaked through the air toward Sans. Fuku tried to shout through her gag, but Sans was already moving. He darted out of the thread's reach, as well as the next four that seemed to anticipate his dodge. The threads came close, but not close enough to wrap around him. Another thread approached Sans's back, only for a glowing bone to slam into it and pin it to the floor inches from Fuku.
The threads came from all directions; while Error doubtless directed them, they gave no indication of Error himself.
"Don't tell me you're shy." Sans said, looking about for some sign of his attacker. "I mean, you're clearly me, and I know how much we love an audience."
"That's why they're here." Came the reply. Sans felt a shudder run up his spine; it was his voice, yet there was something else there, something … unhinged.
"Uh-huh. And you're trying to pick a fight with me because …?"
"Because I'll have to deal with you sooner or later, abomination, and I'd found it's always easier to do it sooner and get it out of the way."
Threads shot from every direction toward Sans only for Sans to vanish. He only intended to be gone for an instant, but the moment he slipped into the shortcut, he found himself staring at the wild-eyes black Sans.
The picture had not been entirely accurate, as the other Sans wasn't black, at least not all the time; his body colors seemed to invert periodically, reminding Sans of a television screen flickering. Aside from the colors, the blue threads extending from his fingertips, and the random presence of the word 'ERROR' flashing spots across the other Sans's body as well, the other Sans looked identical to Sans; same hoodie jacket, same track shorts, same slippers. He had the same grin as well, though there was definitely a maniacal edge to Error's eyes, possibly owing to the bright red and yellow hues.
Seeing surprise in the wild eyes of his other self, Sans realized Error had been hiding in the shortcut all along, sending his strange blue tendrils through while remaining hidden. More blue threads appeared from the yellow tips of Error's fingers, but Sans was already moving. He dodged the threads with ease and grabbed Error's arm. Fury registered on the black skeleton's skull as Sans pulled them both out of the shortcut and back into Grillby's kitchen.
"DON'T TOUCH ME!" Error shouted, yanking his arm from Sans's grasp. A telekinetic blast knocked Sans across the kitchen and over Fuku and Toriel's heads. Sans caught himself with his own telekinesis and landed easily on the table before turning to face Error, another Gaster Blaster forming above him.
The two Sans's stared at each other for a long moment, the room strangely silent as they attempted to stare each other down.
A grin slid across Error's face. "Well, you're quick enough, but you've left your weak point exposed."
"Shows what you know!" Sans said, "I finished off all of Grillby's ketchup a week ago!"
Blue threads shot across the room. Sans tensed his legs to dodge only to realize he wasn't the target; the threads wrapped around Fuku and lifted her from the ground.
"Fuku!" Sans said, stepping forward.
"Lose the Blaster or your old flame's going to be a pile of ash!" Error snapped.
Sans stared into Fuku's eyes for a moment before lowering his hand. The Gaster Blaster vanished with a disappointed groan.
"That's better." Error said, motioning to Fuku. She rose in the air, suspended by the blue threads now wrapping around her waist. "I've taken out more of us than I can remember, ended more of these false realities than I care to count, so I can tell you with some authority that struggling doesn't help; it just makes it take longer and makes the people of this reality suffer. I can make it quick, though; I can end all of you, all of this … this lie in an instant."
"What's stopping you?" Sans said, inwardly urging Glen to hurry.
"Two things; the first involves your little friend over there." Error gestured to Frisk and Asriel. Blue threads slipped around Frisk and lifted her from the ground, causing Asriel and Toriel to struggle all the fiercer to escape their bonds. "You see, Frisk here's the one with determination. She's the one with the power to reset and make things go the way she wants. I take that, and dismantling this place is a breeze."
"So what's stopping you?" Sans said, trying not to call attention to the fact he'd just noticed Fuku slowly moving her hands behind her back. A quick glance by Toriel showed that the bone he'd used to pin one of the blue threads was gone. "You didn't need to call me here to kill the kid."
"No, I don't." Error said, spinning Frisk around idly with the threads extending from his fingers. "But imagine my shock when I catch the fallen child only to find that she doesn't have the dominant determination. Someone else in this reality has surpassed her, someone who doesn't belong here."
Error's smile slowly turned into a frown. "Any idea who that might be, Sans? Any idea who might have the dominant determination?"
"I dunno." Sans said. "This universe's Papyrus? He knows over a thousand ways not to make spaghetti."
ErrorSans chuckled for a moment before seeming to catch himself. "No, it's someone else … someone with an incredible amount of determination. We're talking enough to force reality to alter according to their will. Someone I think you know."
The door leading to the attached restaurant opened, revealing a large bossun man in a server's outfit. "Hey, boss, Tori … my Tori was wandering if I could-"
The bossun stopped speaking, his eyes sweeping over the scene, hesitating slightly over the alternate version of his wife.
"Uh, I take it this is a bad time." Asgore said, backing away and slipping back into the restaurant.
Sans and Error met each others gaze before shaking their heads in unison.
"So let me get this straight." Sans said, "You want this dominant determination person who's blocking Frisk, and if I help you find her, you won't destroy this reality."
"Oh, I'll destroy this reality anyway. That's my job; purging the chaos of the alternate universes." Error said with a carefree shrug. "But like I said, there's a quick and painless way, and a slow and agonizing way. Which would you prefer?"
Glen's head poked over the edge of the back door window just as Fuku looked up at Sans and nodded. Nodding back ever so slightly, Sans said, "It's no skin off my bones."
Error frowned and clenched his hand. The blue threads contracted … or they would have if Fuku hadn't brought Sans's now flaming bone across them, her and Sans's combined power cutting through the threads holding her in the air, leaving the remains encircling her slender waist. She landed on her feet and flung the flaming bone at Error, who quickly teleported away from her, right in front of the window by the back door.
"You cut my threads." Error said, sounding both horrified and fascinated at the same time. "No one's done that since that freak cyborg abomination."
"If I was you, I'd be more worried about her." Sans said, pointing behind Error.
"Huh?" Error turned just in time to see Glen crash through the window and tackle ErrorSans to the floor.
"Pop quiz, funny-face." Glen said, one metal hand wrapped around the base of Error's spine as though to choke him and the other raised to punch him in the face. "You just threatened an entire dimension of innocent people … monsters and humans … and pissed me off personally by attacking my friends. What do you think I'm going to do next?"
ErrorSans stared at Glen for a long moment, eye-sockets narrowing. "You! You don't belong here!"
"That makes two of us!" Glen reached back with a metal hand and grabbed the blue threads that were floating toward her neck and yanked on them. Error flew out from beneath her and smashed into the fark wall of Grillby's kitchen as though some invisible hand grabbed and yanked him as well.
"Huh." Glen said, looking at the now white strands clasped in Headache's metal hand. "Didn't expect that."
She gave the threads a shake; instantly, the threads binding Toriel, Grillby, Asriel, and Frisk also turned white, as did the remaining threads around Fuku's waist. The threads pulled away easily at Fuku's touch as she untied Toriel before moving to her father, Frisk, and Asriel.
Toriel was on her feet in instant, murder in her eyes as she advanced on Error. Fire erupted from her hands, engulfing Error. By the time the flames died down, there was no trace of Error. Fortunately, being Grillby's house, the flames caused no damage. Frisk and Asriel ran to her side, the bossun woman crouching down and hugging them fiercely before doing the same to a shaken Grillby.
"I'm sorry." Grillby said, "I wasn't strong enough to-"
"Shh." Toriel said, pulling him into a tight embrace. "The people I care most about are safe. That's all that matters."
"Tori …"
Sans sidled over to Glen and whispered, "He used a shortcut to run away.
"Yup." Glen said as she expected no less.
"I don't understand." Fuku asked, "Who was he? Why did he look like you, Sans?"
"I don't know." Sans confessed, "But this isn't over. You heard what he said; he wants to destroy this reality, and I'm guessing the 'quick way' is out. Question is, what's the slow way?"
"Look, last time I faced the destruction of a dimension, it took a heck of a lot of planning and ended up setting me back three thousand years just to stop it. That time, the bad guy shattered the barrier between the Dream Realm and mainstream reality."
"And that would've destroyed the universe?" Fuku asked, slipping her hand into Sans's.
"Basically, yeah. It basically froze everyone, mainstream and Dream Realm. Without the barrier, nothing could exist; the dimension's essentially stuck in that final moment. It can be restored, but it takes a lot of power." Glen's hand moved over her heart, her head bowing slightly. "A lot of power."
"So whatever he's gonna do, he needs power." Sans froze for a moment before snapping his fingers. "The Core! It powers Ebott and UNDR-Ground!"
Glen shook her head, a doubtful look on her face. "It's not just about power; you need a crack in reality to force open."
"Trust me, he's going to the Core." Sans said, thinking of Gaster. "C'mon! We'll need to take a shortcut to get there in time! Fuku-"
"I'm going with you." She said, squeezing his hand. "It took both of our magic to cut through those weird threads of his. You need me, so don't you dare tell me to stay here."
Sans glanced at Toriel, Grillby, Frisk, and Asriel. Grillby met his gaze; one look was all he needed to convey he too knew Error was still a problem. His eyes met Fuku's for a moment before he looked back to Sans and nodded in approval
"Wouldn't dream of it." Sans told Fuku as Glen took his other hand. "Now everyone hold on; glitchy bastard might be waiting for us in the shortcut, and I don't want to risk us ending up in three separate dimensions this time."
