It was safe to say it was a party beyond the experiences of any present. Frisk had pointed out that things would take time with setting up communications with the humans, and had opined that the best thing to do would be to start by settling on Mt. Ebott, where there was little chance of them being disturbed. And neither of those could really be started with the sun setting.
They had managed to pull the group back together (except for Sans, who had done his usual disappearing act) and they had gathered firewood. Asgore was... somewhat left out, as they naturally split into groups; Undyne and Alphys were joined by Papyrus, and Toriel seemed determined to stay by Frisk's side. The human felt bad for the king, though, and snuck off to help him- climbing onto his shoulders to reach higher branches, despite Toriel's glares once she realised where they had gone. They returned to her soon enough, content that they'd made the king feel a little less left out- and a little more forgiven.

Now, magical fires dotted the slopes immediately outside the new exit, lending gentle warmth and light to the night. The monsters were chattering, excited; gazing at the stars and the wisps of cloud, a collective cry of amazement punctuating the event of a shooting star crossing the sky. Sans had reappeared with food- to everyone's joy (and Papyrus' chastisement that he should have been helping them outside). Vilkun was in it's element, wandering around ensuring everyone was warm. Everyone seemed happy.

Frisk didn't understand it.
They should be happy too, shouldn't they? They'd fought through the Underground for this. They'd been battered by magic and stalked by monsters, they'd died, and they'd prevailed, against all the odds against them. They had a family, people who loved them. Why? Why weren't they happy?
They leaned against a tree, peering out and watching the celebrations. The moon was just visible now, peering out from a distant mountain, and it had captured the attention of most of the monsters.

Most, but not all, they realised as they pulled back behind the tree and bumped into someone. Startled, they whirled around, almost falling over. A hard, bony hand caught their arm.
"Steady there, kiddo." Frisk looked into Sans' grinning, white face. His eyes, small glowing centres deep in their black sockets, were clearly visible in the low light. He looked just as he ever did. Frisk frowned.
"Are you okay?" The skeleton blinked, clearly taken aback. It was pretty obvious that he should have been asking Frisk that question.
"Sure, everyone's having a good time and all I have to do is sit back and soak it in. But you're not okay." It wasn't a question.

"I- no." Frisk sat down at the foot of the tree and Sans joined them. "I'm wondering when... all of this is going to be taken away."
There was a pause. "Yeah. I know how that feels." Frisk glanced over at him; his eyes were staring off, not seeming to be concentrated on anything. They felt their chest compress. What could they say? Toriel, Papyrus, even Asgore... They all seemed to deeply care. They wanted to stay. They wanted Frisk to stay. And if they told them all how they felt... They'd hug them, and reassure them. And although they still felt like it was all going to go away, just knowing the others didn't believe that helped.

But Sans...

"I'm scared of you leaving, of you abandoning me," Frisk said, before the words could be squashed down and silenced. They closed their eyes immediately after they said it, wishing they hadn't. Stupid. The pause that followed hurt.
"Why?"
Frisk cracked open their eyes and glanced at Sans. His usual grin looked... A little less wide. Were they imagining it? They shook their head and pulled their knees up to their chest, hugging them.
"Come on, buddy. Why?"
"Because." Frisk sighed. They'd started- why not say what they'd just been thinking? "Because the others, I feel like... Like they don't believe it's going to be taken away. And that makes me feel like... maybe they'll stop it from going away. At least for a little bit. But... I don't feel like that with you. And I don't want to lose you. You're my friend."
There was another long silence, and Frisk let their head fall onto their knees. There was excited chatter behind them, but Frisk felt so far removed from it. Like they had done with everything else before falling down into the mountain. Families and friends, security and stability- it wasn't for them, and neither was this celebration. They fought back tears.

"You think I don't believe all this is going to last? Heh. You do seem to know what's going on, don't you?" Frisk glanced over at him- the lights in his eyes had disappeared, making his grin more sinister. They shivered despite themself.
"The question is, buddy- just how much do you know? Ah- not enough to know what I'm talking about, by your face. Forget it." The light returned to Sans' eyes and he turned his smile on Frisk. "I don't want to abandon you, kid. Will that do?"

Frisk frowned. "Sans?"
"Frisk?"
"You're not okay either. Are you?"

There was a pause. For a moment, Frisk was worried they'd gone too far. Then they felt Sans' body hand on their shoulder, pulling them into his chest. They sunk into it, feeling his chest bones on their cheek, through the hoodie that smelled of dirt and smoke. Sans' arms, wrapped around their back. His skull resting on their head. They wrapped their own arms around him, trying to hold on to the moment- a moment of shared vulnerability, a moment where Sans was truly here, with them, not trying to be distant, not pretending to be fine, even if it was just for a few moments. Right now felt real.

Frisk was far from tired of the hug when Sans loosened his grip. He let out a chuckle, although it wasn't like his usual laugh. "Yeah, you know more than you should, kid." Frisk tried to tighten their own grip; but Sans gently pulled them back, so he could see their face. His grin had twisted into something closer to a grimace. "Look, kid- you know I don't like promises. But- as long as I can, I'll be there for you. I promise you that."

Frisk let out a strangled sob and threw themself at Sans, wrapping their arms around his neck and hugging him. But- they shifted, their cheek against his, before pulling back. They raised a hand and touched his cheek. It was wet, and not from them.
They suddenly remembered how Papyrus had apparently cried while they were unconscious. But- for Sans to cry- they looked from their wet fingertips to Sans' eyes, confused. He shook his head.
"Ah, just come here, Frisk." He pulled them back into the hug, holding them as their own tears spilled out. "You're something else, aren't you? If only all humans were like you..."

"B-but." Frisk pulled back, "they... They aren't, Sans. And- and that's, I guess, one reason I'm... Scared. It's... not as nice, out there. Even with the freedom and the fresh air. It was nicer Underground." They wiped at their eyes. "I... think I know the difference between human and monster souls, now. Monster souls are... They're good, I think? They're compassion and love and goodness, and without that there's no soul at all. And h-human souls... I think they're just power. The rest just might not be there at all. And monsters... They think humans are like them. It makes them vulnerable."

"Yeah, we lucked out with you, didn't we, kid? I know they're not all like you." Sans looked up at the stars. "Don't know about your theory, that might be more the doc's territory, but you're not wrong about humans." Frisk gazed at him, but for a while he didn't continue. When he did, it was with a total subject change. "You're shivering."

"Oh... Y-yeah. I, uh, should've brought a change of clothes, I guess. Wasn't planning on this when I... fell." They attempted a wry smile.
"Here." Sans took off his hoodie, exposing his bone arms, and wrapping it around Frisk. They weren't too much shorter than him but he was wider, and it hung off their scrawny body. His grin widened. They reminded him of Papyrus when he was small. They were adorable.
"You look happy!" Frisk smiled themself at his reaction. "I mean... Really happy."
"Yeah?"
"Mm. I'm glad." Frisk leaned against him. "Now you have to stay, so I can keep seeing it. Okay?"
Sans laughed; a genuine chuckle this time. "Sure, kid. Whatever you say."

Toriel had been starting to get genuinely worried; her concern had rubbed off onto Papyrus, despite him initially insisting that since both Frisk and Sans were missing, his big brother would look after the little human. They were starting to get to the point of not caring if they disturbed the party looking for them when Sans appeared.
Frisk was out cold, wrapped up on his hoodie and leaning into his chest. He was using magic to ease the burden of the human- who was, after all, nearly the same height as him. The blue glow of his eye caught Papyrus' attention first, whose relief was... Exuberant.

"Sans! There's the human! Are they okay? Where did you go?"
"Papyrus- please, lower your voice. Frisk must be asleep, I assume?"
"Sure is", Sans remarked. "Out like a light. Which- heh- is something they are not."
"Are they dark then?" Papyrus asked.

"I believe Sans meant they are heavy," Toriel said, before Sans could answer. "I was starting to get very worried! Oh- let me take them."
Sans shrugged, letting Toriel take the human from his arms. She cradled them and checked their hands and forehead.
"Oh dear- they are cold! And so fast asleep... Everything must have been too much for them- perhaps I should go back in, and tuck them into bed..."
"But the human will miss the party!" protested Papyrus.
"I said that I would look after them," Toriel said firmly. "No, I will take them back to my house- the ferryperson won't mind taking us, I am sure."
"Hey, Tori. Let me, I'll meet you there." Toriel stared at Sans in confusion.
"You will-"
"Yeah, I can get us there in a jiffy." Reluctantly Toriel handed Frisk over.
"Well... Very well, but you will stay with them until I arrive, will you not?"
"Sure. See you soon." He winked and turned to walk towards the entrance back to the Underground; he passed behind a tree and was gone.

So this is my first "proper" fanfiction- I've had ideas in my head for years and shared them, but this is the first time I've really sat down to write them out and put them online. I've never so much as dipped my foot into the fanfic community so I'm jumping on the deep end!
As such I would love all comments, but especially constructive criticism. I'd like to improve- but I also want to hear if you read and enjoy!

Either way, thanks for making it this far.

-Ren