Careful. If you keep reading, you are going to have a bad time.
"Welp. I'm going to Grillby's."
Sans started walking, while absentmindedly tucking his gloved hands inside his jacket.
It was a very cold day, even by Snowdin standards. The town seemed emptier than usual, possibly due to that reason. Everyone was most likely inside, enjoying the coziness of their homes while watching the snow fall through the windows. It made him slightly impatient to reach the warmth restaurant and enjoy a nice burger with fries. Just another nice day in Snowdin.
"Papyrus, do you want anything?"
The tall skeleton had started following him as soon as he'd left their place. Walking behind him, however, he'd been oddly quiet. Something was probably on his mind, but Sans wasn't too worried. He'd help him out, as soon as Papyrus felt confident enough to tell him what was going on. The skeleton could be surprisingly hermetic from time to time, but it never lasted too long.
He was just teasing him by asking him that question. Papyrus hated the food at Grillby's. Sans thought that maybe appealing to his so called "standards" would ease the mood a little bit.
"You've got ketchup on your shirt." Was all the tall skeleton replied.
Sans was slightly weirded out by the seriousness of his voice. He looked down however, and realized Papyrus was right. A ridiculously big red stain spread across his shirt. "Huh…?" He thought, blinking in confusion. When he opened his eyes, a second look revealed it was actually just a drop.
"Heh. I guess you're right." The sound of Papyrus's footsteps stopped, and Sans stopped walking too. "What is it this time? Did you forget to triple check your puzzles? Or are you afraid your cooking skills can't improve any further?" He said, without turning around. Papyrus didn't answer. "Has the flower spoken to you again?" Silence. Sans sighed. Something was definitely worrying Papyrus. He turned around, determined to give the skeleton a comforting smile.
"It'll be alright, Papyrus, whatever it is… We'll figure it out…" His words died slowly.
There was no one there.
Sans looked around, but the skeleton was nowhere to be seen. He looked at the ground, expecting to see his trail in the snow, revealing his location, but all he could descry was an object, not too far away from him. He approached it, still looking around for his brother.
"Very funny." He thought. The object in the middle of the snow was Papyrus's scarf. The tall skeleton must've been playing a prank on him, he figured. An odd occurrence. Probably the first time he'd ever done that. The thought made him smile. His smile lost a bit of its brightness, however, when he realized there were no footsteps around the scarf either, except for his own. That was turning out to be an extremely well thought and well executed prank, to be his brother's first one.
Sans kneeled down on the snow and grabbed the scarf.
"Hey, you really got me there for a second." He spoke loudly, to the empty surroundings. "I didn't think you had it in you."
Sans tried to get up, but somehow had trouble doing so. "What…?" He looked down, confused. He was seriously trying to move his legs, but to no avail. "Is this all part of the prank…?" He thought. He tried to ask that question to his surroundings, but he was breathless, and was unable to speak. His entire body felt inexplicably tired. He swallowed thickly, feeling the cold intensify around him. He raised his eyes, only to realize he was no longer in the town, and that he was all alone. He was in the forest, and the only things surrounding him were trees.
He looked at Papyrus's scarf on his lap, trying to figure out what was going on. Feeling dizzy, his eyes were attracted to the ketchup stain on his shirt. It'd started to grow, slowly but constantly. Drops of bright red liquid had started appearing across his entire chest. But at that point he knew it was blood, not ketchup.
"Skeletons don't bleed, dumbass." He heard a voice saying from behind him. He wanted to turn his head around, but his body didn't respond. "You couldn't do it either, huh?" He recognized the voice as Undyne's. The snow had started falling heavily around and on him. "I guess that was it then." Utterly lost, Sans wanted to ask her what she meant, but the words simply refused to leave his mouth.
"We failed." A completely different voice spoke to his back. It took him a moment to realize whose it was. "We failed to protect them all…"
"O-o-old… l-l-la-dy…" He was finally able to speak, but it was nothing but a whisper. There was no answer. Nothing around him made any sense. What was she doing there? What was happening to him?
No voices came around after that. His whole body had grown numb. He was covered in snow, and it was colder than anything he'd ever touched. He could feel it, despite the numbness. The red stain had crossed his entire chest at that point. A bright red that stood out against the whiteness of everything else, covered in snow.
Everything except his brother's scarf.
"Right… there is no snow on it." He thought. "I made sure." A memory came slowly to him. It all started making more sense, even if slightly.
He'd found his scarf. It'd been the only thing. The dust and anything else, he could never find. He'd figured since the scarf had been the only thing, it probably had been covered in dust in the last moment. But the wind and snow had erased any trace of it. He'd cleaned it, taken it back to the house, and hung it neatly in the closet of his room, just like he knew his brother liked to.
His eyes closed, but he forced himself to open them again. The scarf was gone, but it had never been there. Sans smiled, finally remembering.
"Wow… Embarrassing. Hallucinating? Bad way to go." He thought, trying to smile. He was barely able to keep his eyes open long enough to see his surroundings. The pillars, the sunlight coming through the windows… The knife on their hand, as they watched him lay on his knees, struggling not to lose consciousness.
"Sorry Papyrus, Old lady… Everyone…" His eyes closed once again, and he was unable to open them. He tried to picture the snowy forest once again, but this time in his mind, what fell from the sky was dust, not snow, and he gave it a rest. "For once, I really don't want to give up…"
As he fell into the darkness, his last thoughts were a sincere apology.