Sans' POV
As it was no longer his brother's birthday—it was a few months past—Sans slept in, like he usually did. He woke up from a rough sleep, groaning at himself that he had to wake up from his peaceful slumber. After a few minutes of arguing with himself over whether to get up or not, he squinted at his clock to check the time. 10 AM.

He sighed, then sat up in bed, officially deciding to wake his lazy bones up. He noticed a note left on his nightstand, and read it to himself.

DEAREST BROTHER:
I HAVE GONE TO MY DUTIES AS A SENTRY. I LEFT YOU TO SLEEP IN TODAY. DON'T EXPECT TO USE IT AS AN EXCUSE EVERY DAY. I LEFT SOME SPAGHETTI FOR YOU. I EXPECT TO SEE YOU SOON. I LOVE YOU, BROTHER.
SINCERELY, THE GREAT PAPYRUS

Sans chuckled to himself at the note. It was classic Paps.

Not wanting to disappoint his brother too much today, he got ready for sentry duty and headed over to Grillbz. As much as he loved his bro, his spaghetti could never be trusted.

Of course he lingered there, and came to his brother at around 12 PM. Usually he would be there slightly before, but she had cancelled today, so there was no rush.

Immediately Papyrus rushed to his brother and said, "BROTHER, I KNOW I LEFT YOU TO SLEEP IN, BUT I WOULD NOT HAVE IF I KNEW THAT YOU WOULD SLEEP IN SO LATE! WHERE WERE YOU?"

Sans grinned lazily, and answered, "I was practicing in my band today."

Papyrus squinted suspiciously at his brother. "I AM AFRAID OF WHERE THIS IS GOING."

"Can you guess what instrument I play?" Sans continued, the grin having no chance of leaving his face now.

"SANS, NO! DON'T YOU DA—"

"A trombone!" Sans finished, then proceeded to laugh. Very hard.

Steam blew out of Papyrus's ear holes, and he yelled in anger, "NO SANS! NO! I AM SICK AND TIRED OF YOUR PUNS! SICK OF THEM! I COME TO SENTRY DUTY WITH A GREAT MOOD, BUT THEN YOU PULL OUT A TERRIBLE PUN OF YOURS AND IT JUST RUINS THE MOOD! IT RUINS THE MOOD, SANS. SO BASICALLY, CAN YOU NOT?"

Sans snickered, then pulled out a knotted rope and replied, "So you want me to knot make more puns?"

Paps screeched in anger. "STOP IT! I'M GOING TO DESIGN MORE PUZZLES IN CASE ANOTHER HUMAN COMES ALONG. KEEP YOUR PUNS TO YOURSELF!"

With that he stomped off. Sans, as anyone were to expect, regretted nothing, and tucked the rope back into his jacket. You never know what puns you might need to make.

He looked towards the door. She had cancelled for reasons unknown...but maybe he could still talk to her, if she was close enough.

As Sans made his way closer to the door, he thought about what little he knew about her—the lady on the other side of the door. She had never told him her name, and Sans got the feeling she never wanted to. He was fine with that, though. He had never really needed to use her name, anyway, so what was the point in asking?

As he got closer to the door, he swore that he could hear movement. But if she cancelled...who was it? Sans could ask if it was her, but he didn't want to take chances. He stayed silent, and slowly thought he could hear a voice—no, voices. And one of them was the lady's. Unless he was crazy, she was there on the other side of the door... and she was not alone. It reminded Sans instantly of the Frisk case, where they emerged from the door nine years ago. But another human couldn't have fallen so soon...right?

He tried to convince himself of that fact, but doubts creeped into his thoughts and plagued him. Sans shook them off and listened again, but didn't hear anything.

Okay, now he was convinced he was going crazy. He turned away and started walking...when he heard a very loud creak behind him. His first instinct was to teleport and hide behind a nearby tree. He stared at the door. It was opening. That door never opened. The last time it had opened, it was Frisk's arrival into the monster world. But there couldn't be another human...

Could there?

A head popped out of the crack in the open door. Sans blanched. It was another human.
Of course it was another human. Why wouldn't it be another human? The only time that door ever opened was for humans, so therefore, it must have been a human. But this was the first time that two entered within ten years of each other. The first.

Sans watched as the human cautiously opened the door some more, slipped out, then carefully shut the door as quietly as she possibly could before taking her first soft steps in the snow. He took a closer look behind her. Her feet barely left an indentation, thanks to her technique.

His eyes wandered to her face, and he was surprised to see that she was smiling, standing (with no jacket, he realized later) in the snow. She looked up at the grey sky...and started to laugh. Apparently she had given up on trying to keep her entrance secretive, because she spun around in circles, leaving deep footprints of where she had been. Then an odd feeling tugged at him. He felt like...he had seen her before somewhere, but where? And how, was the more important question. Where would he know her from?

He had no time to think, because she suddenly stopped what she was doing and looked around warily. "Who's there?"

Sans freaked. How did she know he was there? He tried hard to control his breathing, as to not hyperventilate and give away his position. He barely managed to succeed.

Then he remembered his sentry duty, and that he was supposed to report any humans he found.

Sans teleported a few yards in behind her, and began to walk towards her. She froze when she realized he was there, and turned to look at him. Instead of being scared, like he thought she might be, she cocked her head and studied him. Sans felt vaguely uncomfortable under her silent gaze, but a stir in his nonexistent gut made another feeling pop up out of nowhere.

He couldn't identify it, though, because it went away as fast as it came.

Sans forced a smile on his face and told the human, "Hey, that's not how you greet someone. Shake my hand."

She looked away for a few seconds, before nervously approaching him and putting out her hand, making eye contact. Sans smiled as they shook, and he heard two farts blast the air. They stared at each other in surprise before looking at their hands. Both of them had a whoopee cushion attached to their hand-shaking hand.

They eyed each other for a moment, then at the same time, burst into peals of laughter. He could hardly breathe. He looked over at the human and saw that she was doing no better; she was crying from all her laughter. Sans smiled at her genuinely this time. They seemed to have something in common—a trait he never came across in someone before. Even Frisk didn't like his puns enormously. But her...already, they were different from every other human that had fallen, even Frisk. Sans realized that he had to protect her. That odd feeling from earlier suddenly resurfaced, but went quickly away again.

Sans waited until her laughs died out before trying to talk to her. The human looked up at him and smiled brightly. For some reason, his soul skipped a beat at her smile.

"That...was...epic," she grinned. Sans grinned back. "That sure was. I didn't expect that. I mean, how often is it that two beings think of the same thing at the same time? Probably a fraction of a fraction of a fraction of a percent."

The human nodded, and replied, "Well, it was nice to know that I'm not the only one. Addicted to puns and pranks, I mean." Sans quickly thought up a pun as a response. "It is a relief to know that I'm not the only punny one out there."

She grinned devilishly. "Yeah. I mean, no one around me finds my puns humerus. Tibia honest, I was worried that I was alone in the universe for a long time."

"I hope that didn't get bonely," Sans countered.

"Nah. I'm usually withdrawn, anyway. But the only reason I'm here is because of a marrow chance of fate."

"Go on. I'm interested a skele-ton."

"Well, I... wait." She stopped what she was saying and glared at him. "You're a numbskull for trying to pry into people's past. It's private!" the human said suddenly, turning away from Sans. This hurt him, although he didn't know why, but he sighed and replied, "I'm sorry. I shouldn't have thrown you a bone. I'll leave you be, if you want."

She twisted around in his direction. "No, I shouldn't have been talking about it in the first place. I probably should have gotten it through my thick skull before I said anything."

Sans looked at the snow, guilty yet relieved that the human forgave him. Then his head jerked up in realization. "Oh yeah! We haven't actually introduced ourselves yet. I'm Sans. Sans the Skeleton." The girl looked unsure for a second, before hesitantly saying, "I-I-I'm Y/N. I'm a human from the surface." Sans snorted. "Yeah, we don't get many in the Underground."

Y/N snickered. "Well, you never know."

Y/N's POV
"SANS!!! WHERE ARE YOU? I'VE BEEN LOOKING FOR YOU EVERYWHERE! WHERE DID YOU GO?"

Sans spun towards her. "Quick, hide behind that conveniently-shaped lamp!" he said, pointing at a random purple lamp that was, conveniently, her exact shape and height.

Questioning the laws of the universe in her head, Y/N gave him a confused look but hid anyway.

She heard heavy footsteps in the snow, and automatically assumed that they were taller and heavier than her. She was used to sizing up people, even when they weren't in front of her or she was looking at them. The reason why? Bullies. Lots of them. She was made fun of and tortured because of her own personality, something out of her control.

Y/N snapped out of her thoughts to listen to the conversation. The apparently always-loud skeleton talked first. "SANS! I FOUND YOU! WHERE WERE YOU? WHEN I LOOKED FOR YOU AT THE SENTRY POST, YOU WEREN'T THERE."

Y/N peeked around the lamp to see Sans sweating. Once again she questioned the laws of the universe in her head, but quickly shook it off as he regained his cool. "Hi Paps. Hi Frisk. I was right here. Apparently you didn't notice me. Well that's not humerus. Tibia honest, I think that's very sad."

Y/N tried to giggle silently as she peeked out behind the other side of the lamp to see who it was.

There was a tall skeleton standing there, wearing a red cape and suited in battle armor, and on his shoulders sat a human. Y/N's eyes widened in surprise. A human? What are they doing down here? Sans didn't tell me about them. She glanced at Sans for a moment, before reverting her gaze back to the human, who was staring with big brown eyes right into hers. They first gave a shocked expression, before coming to confusion. They signed to you in sign language, 'Who are you?'

Y/N nearly winced in her memories. About ten years ago she lost a a good friend to pneumonia. He was deaf, so she learned sign language to help him understand the world. The day before he got sick was one of the only happy days of her life...

Blinking back the memories, she signed back, 'I'm Y/N. I fell here a few months ago from Mt. Ebott. Is that how you got here?'

Their eyes got bigger as they signed, 'I'm Frisk. And yes, I did fall from Ebott. They thought I would be the last human soul, but everyone decided to let me live here with them while they find another—'

They froze, stopping in the middle of their conversation. Y/N signed at him, 'Hey, Frisk, you okay? You seem spooked. What's up?'

'You have to get out of here.' Their signs were quick and frantic, almost non-understandable.

'What?'

'Not Papyrus and Sans, but other monsters, like Undyne...they want your soul, and will not hesitate to kill you if they know you're a human.'

Wh-what?!

[Evil cliffhangers...>:)]