I will embrace my bias and say that this is the most entertaining one because this one was my favorite to write!  

Sans groaned, blinking his eyes open slowly to allow the world to shift back into focus. Judging by his headache and the crick in his neck, he'd fallen asleep outside again. He shifted, eyebrow ridges furrowing when he felt something hard underneath him. That wasn't grass, nor was it his bed, which is where he usually ended up if Papyrus found him. Speaking of which, he couldn't hear his younger brother banging around in their oversized kitchen making breakfast. And it was their week for the kid, and Frisk was usually bouncing around his room and waking him up at some ungodly hour (usually around 8:00am) to help or play a game. Where were they? And was he sitting? He closed his eyes, shaking his head. Stars, it felt like someone was taking a jackhammer to the inside of his skull. He let out another noise of discomfort, feeling his tongue brush against–

Wait, his tongue? That was only summoned if–

Sans' eyes snapped open, headache forgotten as his magic flared up in response to his sudden panic, thin wisps of it trailing from his socket. The room he was in was dark, and very much not in his home, or any of the other monsters' homes. He was sitting, on a hard, wooden chair. His tongue, something that only appeared when something was in his mouth, probed against the strip of cloth shoved between his teeth and tied around the back of his head. He moved to rip it out, but a sharp pain and a glance downward revealed that both his arms were tied to the poles that made up the back of the chair, the rope woven in between his radii and ulnae all the way up to his elbows. Thick ropes were also wound around tightly around his ribcage, ensuring that he was securely pinned to the chair. Further struggle revealed that his ankles were bound equally tight to the legs.

Sans squeezed his eyes shut, bowing his head and trying not to panic, even though he was already hyperventilating. His eye was flickering between yellow and blue so fast his magic was turning green. He shivered, not from the cold, but from the pure terror that made him feel like he'd just been doused in frigid, icy water. He wished he had his jacket. His signature blue hoodie had been making rarer and rarer appearances the longer the monsters remained on the surface, preferring to remain in just his t-shirt and basketball shorts. The only times he really wore it nowadays was when he needed the security and comfort. He really needed it right now.

Through his fear-addled mind, he had enough common sense to try and teleport away, to anywhere really, but the second he attempted to do so blinding pain shot down from his neck straight to his soul. He let out a choked cry, the only sound he could manage as he spasmed in place for a solid minute, breathing hard as the effects of the magic suppressor wore off. Whoever had done this to him had clearly done their research and set up all the necessary precautions. It made him feel sick.

He snapped his head up when he heard a noise coming from above him. Sans stopped breathing, not like he really needed to in the first place. Garbled voices drifted down to him, getting closer. He immediately cleared his face of all emotion – his captors really didn't need to know just how scared he really was – but no matter what he did he couldn't get his eye to stop glowing, only managing to get it to stabilize to solid, bright, ethereal blue. He should be disturbed by how easily he slipped into the mask of 'no fear', but, with the amount of genocide runs he'd lived (and died) through, he couldn't find it in himself to be surprised.

He glanced around the room, looking for anything that could possibly aid him, but finding nothing. It appeared empty, save for himself. He let out a muffled growl of frustration, slamming his head against the back of the chair. Again, he poked at the gag with his tongue, loathing the thing and wishing he could get rid of it somehow, when his tongue slipped and brushed his canines instead, the large teeth the only thing separating his anatomy from that of a human skeleton. Sans paused. He would've face-palmed himself if he was able. With a little bit of effort, he managed to shove the edge of the cloth under his fang, biting down and creating a tear. With a lot more shoving and fraying later, the cloth eventually gave way. Sans was quick to spit it out, grabbing the end with his teeth and flinging it to the other side of the room. With the demeaning gag gone, he felt slightly better.

He was startled by a door suddenly slamming. He instantly smoothed his features, just in time for two humans – both male, it looked like – to appear out of the shadows draping over the room, neither of which were looking at him. He smirked lazily. "hey."

Both humans jumped. "Shit," the smaller of the two exclaimed elegantly. "How did you...?"

Sans allowed his grin to widen, running his glowing tongue over his fangs before snapping his jaws at them, taking far too much pleasure in watching them flinch. The fact that he, even tied up and stripped of his magic, still scared these humans further lifted his panic. "still a monster, remember?" He leaned back, trying to maintain his infamous lazy and carefree demeanor, even though his soul was still tight with fear. "so, mind explaining what i'm doing here? 'cause i've got a brother and a kid to look after and i'd rather get back to them thanks." He couldn't help but shift nervously, grin falling a little, when the two humans exchanged a glance, staring back at him with twin predatory smiles.

"Well, you see monster," the taller hissed, "we don't like you here. We think your whole disgusting race should be shoved right back into the hole you crawled out of. Unfortunately, this the unpopular opinion. So, we've decided set an example." His smile turned feral, a gleam in his eye that reminded Sans far too much of the genocidal insanity he saw in Chara's eyes. "It's just perfect luck that the surrogate father of the 'ambassador' just happens to be the weakest monster in the entire race! Makes our job much easier." Sans couldn't stop the growl that escaped his throat, his eye glowing brighter.

The smaller held up a knife, forcing him to stare at his own tight smile in the blade's reflection. "I wonder what the look on your brother's face will be like when he spots the dust on the doorstep, wrapped in your t-shirt. Will he cry? Or will he just stare, emotionless?" Sans was physically shaking, his magic beginning to flicker between colors again.

"Either way," the taller butted in, grabbing the knife and twirling it between his fingers. "There is nothing. You. Can. Do about it." He accentuated each word with a step closer to the trapped and panicked skeleton till he was right in his face, smiling coldly.

Sans didn't know what to do. The silence rang heavy. He could look nowhere but directly into the smiling human's eyes. He felt his magic subconsciously building up to teleport, momentarily forgetting about the repercussions, he just had to try something. Then–

"Hey wait! Collin! You said I could say that part!"

And just like that the tense, threatening atmosphere vanished in a puff of smoke as the smaller human pouted, crossing his arms and glaring up at the taller – Collin, apparently – as the now-named human closed his eyes and backed away from Sans. "Nate...shut the fuck up. You were taking too long. Besides, you got to say the bit about his brother! I say fair trade."

"But you promised!"

Sans raised an eyebrow ridge, watching as the two dissolved into petty squabbling with sheer disbelief. He blinked a couple of times, his magic dissipating from his eye for the first time since he woke up, leaving him staring with blank, pitch-black sockets. "i...uh..." The humans didn't hear him, or, if they did, they ignored him. He was fairly certain they weren't even talking about him anymore. 'wow...these two are more boneheaded than even i am.' Just as the thought crossed his mind, exhaustion crashed over him like a wave. His eyes began to slip shut. Since the threat was...not a threat anymore, and the fact that his magic had stayed in such a visible form for who knows how long, his over-panicked body was shutting down. The sounds of bickering faded into unintelligible white noise as his head drooped.

His eyes closed, and instantly the peaceful abyss of sleep washed over him.

*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*

"Come on, Nate, that was one time and literally years ago you can't be–"

"One time?! I caught you doing it last week, you dirty donut stealer!"

"Why are we even talking about this! Don't we have more pressing things to deal with?"

"You mean more pressing than your betrayal, Collin?"

"For the love of Christ, Nate–"

Both were interrupted by the sound of low, loud snore. The two humans froze, exchanging confused glances, before turning slowly toward the captured monster before them. His head was bowed low, and he was sagging in his bonds in a way that was not possible to be comfortable. The snore came again, the skeleton's chest rising and falling in time with the sound. Collin stepped forward first, using the tip of the knife still firmly grasped in his head to raise the monster's head, revealing his closed eyes and relaxed expression. "Is he...asleep?!"

Nate's mouth hung open slightly, eyebrow raised. "What...what kind of moron falls asleep in the middle if their own kidnapping?!"

The wall exploded.

The humans stumbled out of the way, letting out half-formed noises of shock and surprise as they scrambled to get out of the way of the rubble. Shadows in the dust formed three shivering silhouettes, then one moved and Papyrus was racing onto the room, panic clear in every bone in his body, an equally fearful and worried Frisk on his shoulders. "SANS?!" He scanned the room, sockets narrowing dangerously when he spotted the two cowering humans, but left them ignored for the time being. He finally spotted his brother to his right, and both he and the child visibly sagged with relief. "SANS!" His relief was short-livid, however, when he noticed how Sans slumped over, ropes tugging painfully at his bones and a magic-suppressing collar fastened tightly around his neck.

The two over silhouettes finally shifted, revealing a dazzling robot with a vampire-like grin and a furious Toriel. "Take care of you brother, darling," Mettaton called, pressing a quick kiss to Papyrus' cheek. We'll deal with the humans." The taller skeleton needed no further encouragement, darting to his precious sibling's side, Frisk in tow.

Mettaton and Toriel turned back to the humans as Papyrus let Frisk slip from his shoulders to help untie Sans, seeing that was he protected and taken care of. Bright, angry flames appeared above Toriel's clenched fists. Mettaton snapped his fingers, and four mini versions of his rectangular form popped into existence, each racing toward the humans and grabbing an arm each, forcing the humans to their knees. Toriel walked slowly toward them, and with each step the flames grew bigger and brighter. "Don't kill them, Toriel darling," Mettaton purred, smiling easily. "I would like a turn as well."

"Oh, don't worry, Mettaton." The Boss Monster's eyes never left the shaking humans. "I just intend on teaching them what happens when they mess with my family."

Papyrus ignored the screams of the two humans in favor of attempting to shake Sans awake as Frisk picked at the knots holding him to the chair. He'd been all too relieved when he spotted his brother unharmed, as even the tiniest of injuries could shatter his fragile sibling. To replace his worry, annoyance quickly pushed its way to the forefront. "HONESTLY SANS, BY THE STARS, HOW COULD YOU FALL ASLEEP DURING YOUR OWN KIDNAPPING! DO YOU HAVE ANY RESPECT FOR YOURSELF?!"

Sans grunted, and his eyes slowly fluttered open. At first they were wide and blank, but then his eyelights gradually faded into existence as he relaxed. "hey paps. dunno why you came. i had it completely under control." He winked lazily, and Papyrus couldn't help but notice that it was with his right eye. The older skeleton glanced down at Frisk, wincing slightly as the humans screamed in the background, and smiled at the child. "hey kid. i'm alright, i promise."

He couldn't help but tense as the kid's bottom lip quivered, but then they were crawling into his lap and hugging him tight. Sans desperately wished he could reciprocate, especially when Frisk pressed their face to the side of his skull. "...I was so scared..." Their voice was barely a whisper, and once the words left their mouth they just clung to him tighter. Sans' jaw fell open in shock. In all the time he'd known Frisk, through every RESET, he'd never heard them speak. Without really thinking about it, he made to snap his fingers, magic bubbling. All he wanted was to get rid of the ropes, he just wanted to hug the kid back. Instantly his soul felt like it had burst into flames, his body seizing as the magic suppressor kicked in. His sockets went dark and his brain fogged over as agony shot through him like lightning. He couldn't even make a sound. His limbs twitched uselessly.

And suddenly it was over. Sans' vision returned to see Papyrus in what appeared to be mid-stroke, holding up the tattered remains of the collar, a bone attack in the other hand. Frisk was still in his lap, gripping his shoulders and shaking him, with tears pouring from their eyes. He was breathing harshly as he looked at them. "h-hey, please don't cry. m'fiiiiii..."

Sans passed out.

Frisk immediately looked to Papyrus, eyes wide, shaking and sobbing. He himself wasn't much better, but he managed to pull himself together for Frisk's sake. He flung the collar as far away from him – and Sans – as he could get it, before raising his attack and carefully slicing through the ropes. Sans instantly slumped forward, with Frisk as his only support. "Mettaton? Toriel?" His voice much smaller than usual, he probably would never have been heard if the humans hadn't stopped screaming. Mettaton turned his head at the sound of his name, then rushed over once he saw the scene, his disco ball attack vanishing in fountain of glitter, as well as the four Mini Mettatons holding up the now-unconscious humans.

The robot quickly scooped Frisk up into his arms, holding the sobbing child close. "Darlings, what happened? Is something wrong?" They were joined by Toriel, who immediately pressed her hands, glowing with green magic, to the sides of Sans' skull.

Papyrus just pointed vaguely to the other side of the room. "Magic suppressor. I think I got it off before it did any real damage, but..." He sniffed, lingering on the verge of tears.

Mettaton knelt down beside him, pulling him into a hug and sandwiching Frisk in between them, "He'll be okay, darling. Nothing a little bedrest can't fix. Why don't we get him home and make him some of his favorite food and just let him recover. He's been through quite the ordeal."

Papyrus stood, standing stiffly for a second before lifting his unconscious brother into his arms and marching out through the way they came. "Yes, let's go home!"