Sans Au Scenarios

His brother

Undertale:
Maybe it wasn't one of your best choices to run away from the big-boned but short skeleton. Now you crashed right into another, much taller, skeleton. Immediately he caught you by your wrist. “I, THE GREAT PAPYRUS, IS SORRY TO- OH MY GOD! YOU ARE A HUMAN?! NYEHEHEHE!!! I DID IT! I FINALLY CAUGHT A HUMAN!” The oblivious skeleton, namely Papyrus the great, didn't notice your shaking and nervous sweating. He only grinned happy down to you. “I NEED TO PREPARE THE PUZZLES FOR YOU. TAKE YOUR TIME TO SOLVE THEM. I MEET YOU IN SNOWDIN!”
With that he let go of you and stormed off to who knows where leaving you dumbfounded behind.
“Well, that went surprisingly well... You didn't even need my puns. Good job, kiddo. You know, my brother is actually pretty harmless.” The skeleton you were running from did of course follow you. You stared at him irritated. “What is it? Am I that scary?” You nod quickly. “Aww. Snow cool. I didn't want to rattle you.” He winked at you with a wide grin and you actually managed to crack a small smile. “My brother, Papyrus, works himself down to the bone just to capture you. You should try his puzzles. They're cool. But don't slip up on the ice or you'll get chilled to the bone. Isn't that humerus? Tibia honest it tickled my funny bone quite a lot.” You giggled along with him for a while until Papyrus came back.
“SAAAANS!!! STOP PESTERING THE HUMAN WITH YOUR TERRIBLE PUNS!” “Alright. Alright... Won't do it again.” “HOPEFULLY! COME ON HUMAN!” Sans just continued laughing. “Hey... I thought you were a monster. Now I see you are a punster!”
Your first words to him were the best in this very moment. At least in his opinion.
If you would stay that way it could at least be a very funny, or rather punny, run.

Underfell:
Since you had left him stand dumbfounded at the bridge he trudged close behind you through the snow, making his rather bad mood noticeable through the noise he was making. “Quit following me!” He grunted. “I'm not followin' ya, I'm just headin' the same way.”
If you had known about his teleporting ability back then, you would probably have punched him right in his bony face.
Of course, he was indeed following you. He couldn't pass on the chance to see how you would stand against his brother.
To his misfortune, you noticed him to early and hid behind a large rock. So all of the tall skeleton's attention was on him.
“Sup, boss?” “YOU KNOW EXACTLY WHAT'S UP, SANS. IT'S BEEN EIGHT DAYS AND YOU STILL HAVEN'T RECALIBRATED YOUR PUZZLES!” Your ears ringed because of his loud voice. “I already done a ton of work to day. A skele- ton.” Sans earned a frustrated growl. “NO TIME FOR PUNS! WE STILL HAVE TO CAPTURE A HUMAN!” “Maybe this rock could help you?” He seriously was giving away your hiding spot?
Fortunately, the tall skeleton didn't listen and stomped somewhat angry away.
“He's gone.” You peeked out behind your rock and glared at Sans. “Tell me please, that you knew he wouldn't look!” He just grinned lazy. “I didn't.”
Now it was on you to growl. “Let me tell you something, Sans, don't get on my nerves!” He shrugged and let you go away again. He would wait ahead and wait for your doom.