They appeared in one of the corridors of the UNDR-Ground's Core. Having been expanded to meet the needs of both the UNDR-Ground and Ebott, it was a lot larger than that of the universes Sans previously occupied. Fortunately, he knew where Error would be heading.
The components of the Core's heart seemed to pulse in the central chamber. Easily ten-times the size of Glen, Sans, and Fuku combined, the Heart hung in the center of the chamber, above a ring of consoles. Countless cords extended from the top of the core like veins from a living heart, pumping energy to the UNDR-Ground, Ebott, and beyond.
Sans and Glen rushed to the consoles while Fuku stared up at the Heart in amazement. "Wow! I knew the Core powered the Underground, but I never actually saw it before."
"The power's just a side-process." Sans said, his finger bones tapping at the console. He let out a sigh of relief when the screen displayed the information he requested. "Power output's steady, no signs of disruption."
Glen didn't respond. Her brow furrowed as she read her screen, occasionally typing at the controls. Sans knew it was only a matter of time before she started asking uncomfortable questions. Had the Sans of her universe told her? No, if he had, she'd know about Gaster.
Sans was debating telling her outright when he felt an icy sensation fill his chest. His gaze fell to find his soul glowing bright through his shirt; slowly moving his shirt, he saw blue threads wrapped around it.
"Sans!" Fuku cried out, drawing Glen's attention from the console. Glen rose from her chair and looked around, calling out, "Let him go."
Sans felt his legs move against his will as he was jerked to his feet like a bad marionette. He was turned to face Glen before the same force raised his hand, pulling the power from him against his will to form a Gaster Blaster
"Duck!" He shouted with immense effort before his hand was brought down. The blast of energy shot from the skull, blasting the console where Glen sat into scrap. Fortunately, Glen had thrown herself out of the way.
"Coward!" Glen shouted. "What's wrong, freak? Can't fight your own battles?"
"Why put myself at risk?" Came Error's reply from behind Sans. Sans tried to turn his head, but found himself unable as Error put his hand on Sans's shoulder. "Besides, you might not be so willing to attack your friend.
A jet of flame shot over Sans's shoulder right into Error's face … or it would have had he not vanished only to appear so that Sans was between him and Fuku.
"Fuku Fire." Error said, his wild eyes looking at Sans. "From one of the Underfell universes, I believe. Strange love interest, don't you think?"
"What can I say?" Sans replied with much effort. "I've got a thing for warm personalities."
"And fiery tempers." Error said with a laugh. "And here I thought I'd seen every pairing there was. Toriel, Rahnna, Alphys, Undyne, Grillby, even Papyrus in universes where you aren't actually brothers …" a pained look passed over Error's skull. "Mostly."
Sans tried not to think about that last one too much. "Why are you doing this?"
"Controlling you? I already explained that."
"No." Glen said. "You didn't. You could've just left this reality and left us alone."
"And rise you spoiling more pure timelines?" Error said, "Not a chance."
Sans's arm shot toward Glen, sending a wave of glowing bones flying at her. Glen clamped her Headache units together, forming an energy shield that deflected the bones.
"What's this crap about a pure timeline?" Glen asked, cautiously moving toward Fuku.
"The child falls to the underground." Error said. "Through either mercy or Love, they leave it. I'm simplifying of course; it's much more complicated. There are roles to be played, situations that must be enacted properly."
Glen gave Error an incredulous look. "So you're saying anything that doesn't fit into one timeline isn't pure? That's just the way alternate dimensions are … er, whoever you are."
"I'm Sans."
"No," Glen countered, "You aren't. Even your so-called pure Sans would never-"
"Sans classic." Error replied automatically. A small hand puppet resembling Sans appeared in the air beside Error. Error's smile widened as he manipulated his strings to make both the puppet and Sans move. "I suppose you could call me Error. As for your friend here, he was a classic Sans … before you showed up."
Glen dove aside as a cluster of bones tore through the ground. "So, what? I should've just let him die?"
"I'm saying you shouldn't have interfered! There are enough aberrant realities without you and your dog sticking your nose where they aren't wanted!"
"Dog? Jake! What did you do with him?"
"He's fine." Error said, an annoyed look on his skull. "For the moment anyway. See, I can't destroy something without it's soul. I suppose you've hidden it somewhere."
"Excuse me?" Glen said.
"The dog's soul! I could feel the remnants within its metal body. Where did you hide it?"
"I … didn't." Glen said. "I've been looking for it myself."
Error stared at Glen for a few moments, giving Fuku, who had carefully edged over to get a better shot at Error, a chance to fire another jet of flame at Error. The tip of the flame caught the edge of Error's sleeve before the dark Sans teleported away. Feeling his hand raise, summoning a Gaster Blaster at his girlfriend, Sans struggled with everything and just managed to stop himself.
"There it is again." Error whispered into Sans's ear. "Such determination in a monster, let alone us … very strange."
Error raised his own hand, only for Glen to shout, "Wait!"
"These alternate universes are like a nasty cold; they just keep spreading and spreading. They're abominations, and I'm the only one doin' something about them."
"Only abomination here is you, buddy." Glen said.
"Yeah." Error replied, smile widening. "But I'm Abomination number one!"
Error clenched his fist and pulled his hand down, forcing Sans to do the same. The blast of energy seemed to engulf Fuku.
"No!" Sans cried out, only to feel the threads binding his soul release; they were still there, but they no longer compelled him to move. He rounded on Error to find his darker self looking at him with an expression of puzzlement. Glen slid to a halt behind him, boots still glowing and Fuku in her arms.
"Thing about changing reality," Glen said with a grin as she helped Fuku to her feet, slipping the luminescent strings from her waist. "It leaves a mark on reality that leads right back on you."
"What?"
Grinning, Glen flicked the strings like a child attempting to crack a whip. Error went flying, the expression on his face making it clear that he had not expected that. Sans felt the bands around his soul loosen as Fuku hurried to him and threw her arms around him.
"Are you okay?" She asked, worry in her eyes.
"I'm fine." He said, rubbing her cheek. "Help me get these things off my soul."
Error rose to his feet, murder in his eyes as he looked at Glen. "How … how dare …"
Glen flicked the threads again. Error rose into the air, the threads extending from his fingertips now holding him in the air. Sans winced, but though the threads around his soul seemed to move, they didn't control him.
"Don't worry," Glen told him. "I'm lookin' out for you, bud. As for you, Error, I've got a few questions for you."
"The … dog?"
"Yeah, we'll get to Jake, but first there's something that's been bugging me for awhile, and seeing you, I think I've finally found the cause. What's the deal with the ichor?"
Sans looked up at Error as Fuku carefully unwrapped Error's threads from his soul. If anything, Error looked confused.
"Ichor?"
"The black stuff." Glen said, shaking him by the threads. "You've been goin' on about destroying alternate universes, so don't even try to play dumb about it. From what Sans said, the last dimension he was in is swimming in the stuff now. I took care of the last bit of it from the last universe I was in, but something tells me I'm gonna be seeing your black goop in other realities. So what is it?"
Error shook his head. "I don't know."
"Oh, come on now." Glen said, swinging the strings and by association, Error. "You expect me to believe that? You come here claiming you destroy universes, and there just happens to be this crud infesting universes-"
"Wait." Sans said, "Error, you said I was from a pure timeline before Glen came, right?"
Error nodded.
"Then why would there be ichor there?" Sans said, looking at Glen. "Frisk had that stuff in her before you every arrived; you just drove it out of her."
"That …" Glen sighed. "That's a good point."
The strings tugged in Glen's hands. "Oh, no you don't!" Glen said, pulling the threads with both hands. This time, however, Error remained in place. After a few more tugs, Glen realized it was worse than she thought, as the threads were now wrapping around Headache.
"Seems like it works both ways." Error brought his hands up, pulling Glen into the air by her arms. Fuku had freed Sans's soul, but the threads now wrapped around her hands and arms as well, lifting her into the air as well. Sans shot a bone at the thread, only for the thread to slice the bone neatly in half.
Sans rounded on Error, twin Gaster Blasters appearing in the air to blast the self-proclaimed abomination number one into dust. "Let them go … NOW!"
"Or what?" Error said. "You'll kill m-"
The gaster blasters fired in unison, destroying most of what was left of the consoles. Fortunately, it was only monitoring equipment; still, when the light faded, Error was still there, his grin spread across his face.
Sans never considered himself a violent fellow, which is why it shocked even him when he reared back and punched Error. It was a stupid move; he didn't have the kind ot strength to do any physical damage with such a blunt assault. Still, it seemed to catch Error off-guard … at least until the second punch. Blue threads caught Sans's fist, quickly slipping around his arm and pulling him into the air with the others.
"Wow." Error said, shaking his head. "I've taken down a bunch of us in the past, but I've never had a Sans try to punch me before. You didn't even hesitate with your gaster blaster either; clearly finding a bit of love's given you a bit of LOVE."
Error chuckled at his joke and shook his head. "Well, this has been interesting, but I think it's time to end this place. Oh, and don't worry about your canine friend, Glenda; I'll see to him soon enough, no matter what music he plays."
"Music?" Glen said, eyes widening. To Sans's shock, she started singing as loud as she could. There were no words, just the notes of a sad melody. After a glance at Fuku found her as dumbfounded as he felt, Sans looked at Error only to find his expression fallen, a single tear leaving another blue trail from his eye-sockets. The threads slowly lowered Sans, Fuku, and Glen to the floor. Fuku was the first to slip out of the threads. As she hurried over to Sans to help him, Glen wrapped the remaining slack of her threads around her metal knuckles. In moments, the threads were once again shining.
"All right, Error." She said, "Let's take this outside."
"What?" Error said, breaking from his strange reverie only for a look of anger to fall over his skull. "How dare …"
"Take it easy, Sans, and make sure Fuku's happy, all right?'
"Huh?" Sans said as Fuku worked at the threads around Sans's right hand, lifting him slighty with her other hand to get a little extra slack.
"As for you, Error, let's take this outside!" The threads extending from Glen's hand shone brightly as she pulled the crystal with the imprint from her pocket and wound some of the threads around it. She flicked the remaining threads around Error and pulled him close, only for the both of them to vanish a moment later in a flash of light.
Sans and Fuku stared at the empty space, barely registering the sound of approaching footsteps until Undyne, Papyrus, and at least twenty knights of the royal guard rushed into the room armed to take on a behemoth.
"Oh, thank goodness!" Papyrus said, "You are both unharmed! The other Lady Toriel told us about the other you, the murdery one with blinking bones."
"Where is he?" Undyne said, a shining blue spear in her hands. "We'll smash him into dust!"
"He's gone." Sans said with a sigh of relief. "Glen must've teleported both of them out of our dimension."
"Hmm." Undyne said, clearly not convinced. "All right. I want a constant presence here in the chamber, twenty-four seven! I'll contact Alphy … er, Alphys about getting some techs in here to fix this place up." A hopeful look came over her face. "Maybe she'll let me install a turret this time."
"I volunteer for the first shift!" Papyrus said, raising his hand.
Alphys nodded. "Fine. Dogamy and Dogessa, you stay here too. Any sign of trouble and you contact me immediately, understand?"
"Yes, Captain!" Papyrus said, snapping a salute at Undyne.
Undyne departed, looking a bit disappointed, likely from missing a good fight. As Dogamy and Dogessa took up positions beside the entrance to the Heart chamber, Papyrus approached Sans and Fuku.
"I am sorry about your friend." Papyrus said.
"Glen?" Sans said. "Heh. I'd feel more sorry for Error. Seriously, I think we really lucked out; if she hadn't been here, there's no telling what that … thing would've done."
"Well, you're safe; that's all that matters." Papyrus said, smiling at him and patting him on the shoulder.
Sans smiled back, but before he could respond, Fuku's hand grabbed his own. He turned to her to find her staring at the end of the thread still wrapped around his wrist. Like a trail of gunpowder ignited, the end of the thread glowed brightly and moved inward toward Sans, the thread behind it vanishing. As this process passed over a portion of the broken Heart console, both the thread and the console vanished.
Sans felt Fuku's grip tighten as the light neared them. His eyes met hers for a moment before the brilliance enveloped them both.
ns 15.158.61.45da2
