When Sans opened his eyes, he and Papyrus were standing by the table with the hunk of frozen cheese. His brother's heartbroken expression answered any question of whether Papyrus remembered their ill-fated battle with Chara.
"guess... not everyone wants to be friends," he said awkwardly.
Papyrus suddenly pulled him into a tight hug. "SANS, I'M SO SORRY. I TRUSTED THEM, AND THEY... THEY KILLED..." Sans could feel him shudder.
"it's all right, pap," he said. "i fell for it too. for a minute there, i really thought..."
Papyrus shook. "THEY KILLED YOU. TRULY, I AM... A TERRIBLE BROTHER." Tears welled up in his eyes.
"what? no!" Sans hugged Papyrus even tighter. "it's not your fault! if i hadn't decided taking a nap in the snow was a good idea..."
"IT'S NOT YOUR FAULT EITHER, SANS. I CAN HARDLY BLAME YOU FOR GETTING TIRED! ALTHOUGH..." He pulled back a little bit, looking Sans in the eye. "PLEASE DO TRY NOT TO FALL ASLEEP IN THE SNOW IN THE FUTURE. THAT CAN BE DANGEROUS FOR YOUR HEALTH! YOU WORRIED ME..."
Sans chuckled weakly. "yeah, uh, sorry about that."
Papyrus smiled. "IT'S ALL RIGHT. JUST, IF YOU FEEL SLEEPY, TELL ME! AND I WILL CARRY YOU WHILE YOU REST."
Sans reached up and brushed away some of the wetness on his brother's cheek. "you're the best brother i could ask for," he told him. "don't you ever believe otherwise."
Papyrus smiled falteringly, before frowning. "...SANS. IF THEY KILLED US... HOW IS IT THAT WE ARE ALIVE NOW?"
"you know, i..." Sans hesitated. "i'm not quite sure."
He didn't know how to explain it to Papyrus, but he had felt something while he was dead. The will to keep living, the fierce desire to change fate - to change his brother's fate... had that feeling brought them back, somehow?
"we can figure it out once we're out of snowdin," he decided. "we probably shouldn't wait around any longer, though."
"LET US CONTINUE ONWARD, THEN!"
Sans smiled. His brother still seemed a little shaken, but determined to keep going forward. As long as Papyrus had hope, then Sans felt like everything would turn out all right.
"COME ALONG, SANS!" jerked him out of his reverie, and he hurried to catch up with Papyrus. He had just done so when Papyrus came to an abrupt halt, and Sans accidentally walked right into him.
"what's the hold up, bro?"
"THE PUZZLE! SOMEHOW IT'S BEEN... UNSOLVED?"
Sans stepped to the side to get a better look, and saw that Papyrus was right. The puzzle in question looked just as it had when the brothers had first encountered it. Furthermore, there was no trace of anyone having been there recently, human or skeleton.
"huh," he said. "papyrus, i think we might have... time-traveled?"
"LIKE ONE OF YOUR SCIENCE FICTION STORIES?"
"monsters and magic are real. no reason time travel can't be too."
"...I SUPPOSE NOT."
Sans grinned. Time travel was way cooler than magic, anyways. "let's just do the puzzle. should be easier, since you already figured it out."
Papyrus brightened up. "INDEED! THE MEMORY IS FRESH IN MY MIND! FOLLOW MY LEAD, BROTHER!"
Under Papyrus' lead, the brothers carefully solved the puzzle. It was only a few minutes before Papyrus decisively stepped on the switch that completed the puzzle, retracting the spikes that blocked the way. Papyrus gave a shout of victory; luckily, the only Royal Guards that heard were a pair of dogs. Rolling in the snow and petting the dogs appeased them easily enough, which was good, because rolling around and petting were Papyrus' natural reactions to dogs.
To Sans' relief, Chara was nowhere to be seen as they entered the next area. They did meet another dog, one who loved to be pet even more than all the other dogs they had encountered - to the extent that its neck grew longer and longer as Papyrus repeatedly attempted to pet it. Eventually, however, it was too tall even for Papyrus to reach, and he reluctantly bid the dog farewell. Sans almost wondered if Chara was the only member of the Royal Guard who wasn't a dog.
As his brother examined the next puzzle, Sans looked around and was startled by a glimmer of light that seemed to come from a nearby tree. Inspecting it, he found a camera hidden in the branches. Well, that wasn't unnerving at all. Hopefully it didn't belong to Chara, because if it did, he wasn't sure how they were going to avoid being caught. He considered breaking it, but decided not to in case that set off alarms of some kind.
Before they had fallen underground, Sans would have never thought that he would have reason to be grateful for Papyrus' fondness for puzzles. Papyrus' passion was certainly paying off now, however; having fully grasped the mechanics of the Xs and Os, Papyrus (with Sans' help) was able to solve the puzzle faster than he had originally solved the previous one.
Even as they moved into the next area, Sans heard the distant clanking of armor. "we'd better hurry," he said, and Papyrus nodded, frowning. Luckily, the next puzzle proved to be a reprieve. The puzzle was in the shape of a skull - and judging by the closed eyesockets, Frisk's skull. Compared to Chara's puzzles, this one was a breeze.
After Frisk's skull puzzle, their luck ran out. They were in the middle of trying to solve the next of Chara's puzzles when a familiar voice rang out from behind them.
"Two humans?" said Chara. Sans' heart sank. "It must be my lucky day."
The brothers turned around to face their opponent. "KILLING PEOPLE ISN'T VERY NICE, YOU KNOW!" Papyrus admonished them.
Chara considered this. "If it makes you feel better," they said, "your deaths are going to make a lot of monsters very happy." They smiled. "Especially me."
Their souls floated out from their bodies. Time for another battle.
Why Sans wasted a turn 'checking' Chara, he wasn't quite sure. Maybe it was that he hadn't gotten hit yet, so there was no need to heal, and he didn't particularly feel like talking to them. 20 AT and 20 DEF - way more than any of the other monsters they'd fought thus far, with the single exception of Toriel. (In hindsight, Toriel must have been really holding back, even before her attacks started avoiding them.)
He was getting good at dodging, if he did say so himself. But - he grimaced - Papyrus wasn't. In fact, his brother was spending most of his turns healing - but they were running out of healing items. Only a lonely Spider Donut left.
He almost wondered if now was the time to start fighting back. But... no. Chara might be a murderous, backstabbing skeleton, but they had a sibling who loved them, and hurting them would hurt Frisk, too. Besides, Papyrus wouldn't be able to bear hurting anybody. Even now he was trying to convince Chara that they didn't need to kill.
No, fighting Chara was right out. There had to be another way.
Maybe - he winced, not quite managing to dodge one of Chara's bone attacks in his distraction. He looked over to his brother. Papyrus looked worn and battered in a way that tore at his heart.
Papyrus opened his mouth, no doubt to continue to try and talk Chara into mercy (the non-pretend kind), but Sans stopped him. "wait," he said. "just - wait a minute, okay?" Papyrus nodded.
Chara wasn't going to show them any mercy, and Sans didn't want to see his brother die again. Really, it would be best if, as Frisk hoped, they never encountered Chara at all - but it was too late for that now... wasn't it?
Sans focused on the present. Another attack or two and his brother would die, and he refused to let that happen again. He scowled just thinking about it. No, he wouldn't let that happen. This was not their fate.
The fires of determination welled up in his soul again, and Sans seized the feeling, concentrated on it. He saw Chara tense in preparation to launch another attack, but it didn't matter, because everything faded into darkness.
And then the darkness faded into a familiar room with a frozen block of cheese.
"SANS, WHAT...?" Papyrus blinked. "WHY ARE WE BACK HERE?"
Sans looked at the snowy ground. "they were about to... uh, win again. didn't want that happening."
"SO IT IS YOU WHO ARE TAKING US BACK IN TIME?"
"guess so." He shrugged, then looked up at Papyrus, an idea occurring to him. "hey, now that we know the answers to those puzzles, we can solve them again quicker than last time, keep ahead of chara. after all, their whole plan to trap us relies on our getting stuck on a puzzle... but if we know the solutions beforehand, they'll never have the opportunity to catch us, right?" He grinned, relieved to finally have a plan. It might take a few tries, but they would get out of this. He could feel it in his bones.
"THAT IS AN EXCELLENT IDEA, SANS! ONLY... YOU STILL HAVE NOT EXPLAINED HOW YOU TIME TRAVEL!"
Sans shrugged. "it's kind of hard to describe." He wasn't sure if he could explain how if he tried. He didn't have a time machine, like in some of the sci-fi books he'd read. No flux capacitors - just a gut feeling, a will to change fate.
"...VERY WELL. FORWARD, THEN!"
As the two made their way to the next puzzle, Sans contemplated his newfound power. A chill ran down his spine as a thought occurred to him:
Could this be the 'power to control this world' that Flowey had spoken of inheriting?
Author's notes: With this chapter, we have caught up with the AO3 version! By which I mean: here's where I run out of the material I have written already. I am working on the next chapter, but... I'm not exactly the most reliable. I'm also finding school very stressful right now, so... we'll see. \_(ツ)_/¯