Hey guys! I hope you are enjoying the fanfic so far! And I just wanted to let you guys know that you guys are able to request different AU's for this story! Though Not all of them may get in, please do request, and I will try my hardest to fit them in! Thank you guys again for reading, and please leave a review telling me if you like it or not!

Chapter 2: Underfell

UF!Sans POV

Sans growled out angrily as he followed the taller skeleton ahead of him. They have been bickering all morning, or, ever since Papyrus found Sans asleep at his sentry station, like always. This caused Papyrus to wake Sans up in a not-so-friendly way, then shout and rant onto him for being a such a lousy guard and brother. Sans snapped back at everything Papyrus said, making comebacks whenever he was able to. It really wasn't his fault for falling asleep, he was just so tired all the time. His insomnia always keeps him up at night, along with his fear of someone possibly breaking in. He knew he shouldn't be afraid of it, seeing how he was living with the 'Great Papyrus of the Royal Guard.' Only those with a death wish would break in. But then again, it was kill or be killed after all, and killing the great Papyrus would make that monster definitely superior. It was a shame that the monsters were dusted way before they could even think about attempting it. In all honesty, Sans would have loved to go at the very least a day without Papyrus' constant bickering. Death would be a little extreme, and if he was going to be honest, he doesn't want Papyrus dead. Of course there was the fact that Sans was only alive because of Papyrus, but also because no matter how cruel he could be, he was still his brother, and they were only so cruel to each other so they could survive their dammed world. They needed to know how to deal with cruelty and how to face strong attacks. If they didn't they would have been dust while they spoke.

"-HIS IS UNBELIEVABLE! I-SANS! ARE YOU EVEN LISTENING!?" the sound of Papyrus' angered shouts and a slap to the back of Sans' cracked skull shocked him out of his musing. Sans grunted at the sudden action and glared at Papyrus. "Hey!" he snapped. Papyrus simply folded his arms and glared down at Sans.

"THIS IS EXACTLY WHAT I'M TALKING ABOUT, SANS!" Papyrus growled out. "I SWEAR I DON'T KNOW WHY I PUT UP WITH THIS. YOU HAVE GOT TO STEOP BOONDOGGLING! IT IS ONLY GOING TO GET YOU KILLED!" Sans had finally had enough with the constant bickering. It was time to stand his ground. And stand his ground he did. He straightened his legs and clenched his fists. The corners of his frown turned down even more, his sharpened teeth, along with the one golden tooth, stood out as he began his angered speech.

"You know what, Boss, I've had it about up to here with your constant bicker- "Sans was cut off from his speech when he noticed a bright flash of white light appear in the distance. It was obvious that Papyrus had seen it too, because his head snapped towards where it had come from as well. With a loud, annoyed grunt from the taller skeleton, he began walking towards where it had come from to find the source, while Sans followed behind just as annoyed, but a bit more nervously. Another thing Sans never liked was being around any of Papyrus' fights. Papyrus could end up being a relentless killer at times, and made sure most fights ended slowly and painfully. It disturbed Sans how cruel his brother could be at times. But his cruelty was the only reason the two were still alive and never threatened by others. And he knew that if there was someone out there that caused this flash of light, it wouldn't be a pretty sight.

By the time the two had made it to the spot where the light came from, the two skeleton brothers noticed that it was a clearing just on the edge of town. Another thing they noticed was that there wasn't another monster in sight. Papyrus turned and faced Sans with clenched fists.

"SEARCH AROUND. WHOEVER WAS SPYING ON US COULD NOT HAVE GOTTEN FAR." He ordered. Sans complied with a frown, and the two split up and searched around the clearing. Sans stayed cautious as he looked, of course. Being a one HP monster meant you had to be careful. One screw up, one mess up, and he was dust. Yet another reason he hated Snowdin. There was always that chance of getting killed at any moment of every day.

Sans shook himself out of his musing when he noticed something from a distance. After getting a bit closer, he got a good look, and saw it looked like a camera, with something wrapped around it. He raised a boney brow and he turned back to Papyrus who was a good distance away, still searching around.

"Hey boss! I think I found somethin'!" Papyrus turned around and looked towards Sans, who walked closer to the camera. Papyrus decided to walk over and see what it was.

"It looks like a camera, but there's something attached to it," Sans explained the simple details out loud to Papyrus before he bent down and picked it up. He had almost brought it up to eye level to inspect it further, but then there came a small hum from it, which made Sans give a confused look. "what the-"

Before he could finish, a white, blinding light came from the camera, and Sans had to let go of it to cover his eyes. He stumbled back, tripping over the snow and falling right onto his back as he covered his eyes in pain. There was a loud shout from Papyrus, as he saw the flash as well, and came running over. But by the time he got there, all he saw was Sans on his back, covering his eyes. No camera, or anything that would have been the source of the light. With a disappointed look, he turned to face Sans again.

"GET UP," He ordered. Sans took a second before slowly taking his hands away from his face, and squinted his eye sockets open. Now able to see, he slowly stood up and looked around. His sockets wide now, he turned his head in every direction. What happened to the camera? How the hell did that thing even do that? Where did it go? He faced Papyrus again. "Tell me you saw it too," Sans said quickly. Papyrus didn't seem to understand what he meant.

"WHERE DID THE LIGHT COME FROM?" Papyrus demanded an answer. Sans only shook his head. "There was a camera! I-it blinded me, then disappeared."

"THIS IS NO TIME FOR YOUR LOUSY GAMES, SANS. WHERE IS THE CAMERA?"

"I swear boss! I don't know!" Sans shot back quickly. Papyrus continued to glare him down for a moment, before finally believing the shorter skeleton.

"FINE. KEEP SEARCHING FOR IT. I'M GOING TO SEE IF I CAN FIND ANYTHING MORE USEFUL FOR THIS. NO SLACKING OFF," Papyrus snapped the last part out threateningly, and Sans only nodded quickly in response. After that, Papyrus stormed off, leaving Sans to himself, who was finally able to relax his bones.

He searched for a while, mostly around the perimeter of the clearing, then started looking through the beginning of the words. There was nothing for a while. No monsters around the area either, which was slightly strange, but seeing it was on the edge of town, he didn't think much of it. Most people liked to stay inside their homes, where it was safer, either that or at Chilby's, where they could get a meal and a drink. Though that place was never too busy, either. Sans went there often to get away from Papyrus, or to get information from Chilby when they needed to.

Another white flash of light brought Sans out of his musing moments later. Looking over to where the flash came from, he saw that it was back in the center of the clearing. Instantly, Sans started walking towards where he saw the light disappear, his eye sockets narrowed slightly as he readied to face whatever it was. He was at the edge of the woods, and was about to enter the clearing when another flash of bright light appeared in front of him. He made a quick yelp, shielding his eyes from the bright light, then heard another yelp from another monster. Before Sans could open his eyes, a large amount of weight toppled onto him, bringing him and whoever it was on top of him down. Quickly becoming frantic of getting caught or ambushed, Sans let his magic take over and grasp the person on top of him, and swung them against the nearest tree. Feeling the weight gone, Sans quickly stood up, not letting is magic go as he glared at whoever it was. Seeing the person, his sockets widened slightly and his magic dropped unconsciously. He had slammed Papyrus into the tree. No…that wasn't right. This wasn't Papyrus. He sure looked fairly similar to him, but it wasn't the same. First, his sharp teeth were gone, replaced with flat ones. The crack in his skull wasn't there either, and his armor was replaced with an orange sweatshirt and baggy pants. His boots, too, were replaced with socks and slippers. This wasn't Papyrus. It couldn't be. Whoever tried to copy him did a pretty poor job. Sans narrowed his eyes again and let a few bones appear and surround the fake Papyrus, who in response quickly put up his hands in a surrendering gesture.

"Hey buddy, calm down," even his voice was similar to the Boss's, but the tone was more laid back and cautious than threatening and dangerous. Sans kept the bones surrounding him.

"Who are you? What are you doing here?" Sans ground out the questions angrily. The taller skeleton seemed a bit shocked at how threatening he tried to sound, but put his lazy smile back on, but only this time it also held a bit more guilt. "Hey now, I didn't mean to land on ya. Why don't you just put those bones away before one of us get hurt, huh?" Sans only gave a dark chuckle in response. "No way, buddy. Not until you tell me why the hell you were spying on us, and why you're trying to steal the boss's look." Sans let the bones get closer to the fake Papyrus, who side glanced towards them, letting his smile fall slightly.

"Alright alright. Look, we don't have all that much time to explain, so how's about you come with me, and I can explain it back home." He said, his voice low and cautious, as if he were talking to a dangerous animal. Sans laughed out loud to what he said. He laughed for a fair amount of time before looking back at the taller skeleton,

"heh, you've got some sense of humor. You think I'm going to follow you to wherever the hell you came from? You've got to be joking. Now let's get serious. Who are you?"

Before the taller skeleton could answer, Sans was surrounded by a blue aura, and thrown against a different tree, further away from the taller skeleton, causing the bones to disappear. Suddenly another skeleton stood in front of Sans, a skeleton who wore a tight smile. Sans' eye sockets widened as he stared in shock. The skeleton that stood in front of him was…him? A different him? No doubt that this skeleton looked fairly similar to Sans, besides his clothing, teeth and lack of scar. Not only that, but his eye, too. Sans' eye glows a dark red color, this…Sans' eye was glowing a bright blue with a little yellow in it. Sans could do nothing other than stare for a moment.

"Sorry buddy, did I catch you off guard?" The other Sans chuckled out coldly, sounding exactly like him. After a moment, Sans finally found his voice. "What the…what the hell is going on here!?" He shouted out. He tried to move off of the tree, but his body didn't budge, as the other Sans still kept his magic surrounding him.

"We'll explain it back home." The short skeleton said before turning back to look back at the fake Papyrus. "You alright?" He asked. The taller skeleton nodded, and looked towards Sans. "Let's get outa here, then. I don't want to stay here any longer than we have to, there's a higher chance of getting stuck."

Before Sans could even ask what they were talking about, they pressed a button that was attached to something around their necks, then a blinding white light, like the one from before appeared. Ten, a skull crushing pressure appeared so quickly and so painfully, that he blacked out.

UT!Sans POV

The process back home wasn't nearly as painful as it was to get back. Maybe for them at least, but not for the new Sans. When they made it back to the shed, the skeleton was passed out for a moment, which he had no problem with for the moment, as he could quickly relax and look over and figure out who it was.

He hadn't noticed that Papyrus had come to inspect him as well, too deep in concentration to even care at the moment. Looking him up and down, he could see that this Sans wore a jacket similar to his, only this one was a dark red. His teeth, too, were different, as they were sharpened to the point, and one of them was replaced with a gold tooth. Not only that, but he also had a crack that started just above his left eye socket, and went just past the top of his skull. It didn't look painful, but it did pop out. Sans had noticed before, as well, that his eye was glowing a dark red, but he couldn't find that very odd, seeing how his outfit seemed to match the color.

A small groan from the new Sans brought him out of his inspection, and he watched as the other opened his eye sockets slowly and put a hand up to his forehead. "ugh…what happened?" he questioned to himself, before remembering what had happened. Sans watched as the other him glanced up, and before he could react, someone grabbed the hoodie of his jacket and pulled him away, just as a bone shot up from where he stood a split second ago. Sans looked over to see Papyrus giving him a small grin, and he nodded for a thanks. The other Sans was up on his feet by the time he looked back, and as looking frightened, angry and confused.

"What the hell is going on? Where am I?" He shouted, trying to sound threatening, but Sans could hear the fear in his voice.

"Welcome to UnderSwap." Papyrus decided to answer, giving the other Sans a lazy smile, but let that smile fall right after. "We brought you here because we need your help."

"Wait a second…UnderSwap? You mean that made up universe with the happy-go-lucky versions of everyone? Buddy, I don't know how you even know the name of it, but the place isn't real." The sans replied with a frown. "No more screwing around. Where are we?"

"You think we're joking?" Sans responded this time. "Common pal, I thought you would have figured it out by now. Yeah, sure, it's hard to believe there's another universe with another version of you and everyone, but by now, it's kinda hard to deny it now." He said with all seriousness. The UnderFell Sans stared at him for a moment, as if trying to both deny and accept what was going on around him. After another moment of pondering, he glared back at the two.

"Alright then...even if this was UnderSwap…why do you need my help?" He asked. Papyrus frowned again and sighed. "Because another Sans has taken my brother, and we can't stop him alone. So we're trying to gather as many Sans' as we can to help us." He explained. UF!Sans stared at him for a moment before crossing his arms. "And why should I help you?"

"Because he's not going to just stop there, and if we don't stop him, he'll destroy your universe like he did with my timeline." Papyrus shot back at him, looking more angered than anything now. Sans put a hand on Papyrus' arm, and gave him a look. Papyrus glanced back at him before sighing, and pushed away any tears that built up in the back of his skull.

"Look…I don't care if it's for my brother or for your timeline. Just, help us out here…please." Papyrus' voice was quieter now, and Sans could understand why. Error had UnderSwap Sans, and who knows what he could be doing to him, if he was even still alive. UF Sans seemed shocked at his tone of voice, before looking down for a moment, looking like he was deep in thought. After a minute or two, he finally looked back up.

"Alright…fine, I'll help you idiots. But only for UnderFell…" he muttered out the last part, and Sans gave a bit of a thankful look for his answer. Looking away, UF Sans spoke up again. "Who are we dealing with, anyway?" He questioned.

"Error Sans," Sans answered. UF Sans' eyes widened slightly as he looked back at the two. "Error? You want to pick a fight with Error?" Sans shrugged slightly and nodded. UnderFell shook his head and sighed. "what have I gotten myself into…" he muttered quietly. Sans chuckled slightly at that and looked towards Papyrus.

"Alright. We have our next teammate, we should get to the next timeline tomorrow. It's already gotten pretty late, and we don't want to overwork the machine too much," Sans explain to Papyrus, who looked back and nodded. Sans could tell automatically that Papyrus didn't want to stop, but they didn't have much of a choice. Things could get sloppy if tired, and that's the last thing they needed. Also if they used the machine too many times at once, then there would be the chance of overworking the machine, that would cause it to either mess up and send them in completely different places, or just directly send them to the void, which there was no way out, as far as he knew. He looked towards UnderFell again.

"You can bunk on the couch for now. Papyrus," he turned to look at Papyrus. "I'll need the travel piece so I can tweak with I and make sure it'll be able to go far enough to reach the next closest universe. You should go rest for now." Papyrus nodded and slipped off the travel piece that was around his neck, and laid it in Sans' hand, before turning so UnderFell.

"Alright, let's get the couch set up." Papyrus said, giving him more of a tired smile now. UnderFell only nodded in response as he followed Papyrus out. Sans watched the two leave before taking off his travel piece as well and moving towards the machine.

"This might take more time than I thought…"

Hey guys! So yes this was a very quick update, and I hope you guys are enjoying it so far. I'm sorry that this one may have been a little more confusing with the two Sans' being there, so I've decided that UnderFell Sans is just going to be addressed as UnderFell, like how all other Sans' will be called for their universes when their times comes, all except for UnderTale Sans, since he's the original, so he'll just be known as Sans. I hope that helps in some way, so until the next Chapter, enjoy!

P.S. I said it before but I'll say it again just in case, if you want a certain AU in here just request it in the comments, and I will try my best to fit it in there as best as I can!