Note this is NOT UNDERLUST but PASSIONTALE. I am writing this to inspire a friend.?
As Papyrus looked on at the two communicating at the bar, he noticed Sans's expressions. He was surprised to see how happy his brother looked at first before everything went sour and the girl got up took something and left. He thought he saw their face but Papyrus couldn't make it out. There were too manny fans clawing at his boots. What he did see was Sans chasing after them however, and as soon as he saw his brother run out the door Pap jumped of stage and tried to chase after them. But with the groups of adoring fans coming up to touch him it was difficult to get by. "AH! PLEASE LOVELIES LET ME THROUGH! I, UH SAAAAAANS!" Pap called out as he forced his way through all the uncomfortable touching as ran out the door. Leaving Grillby to handle an angry and jealous crowd of girls.
Following after his brother Papyrus could bearily make them out as they both got a head start. "I can hardly see them through this mist." He whined covering his face from the cold. It didn't last though as Papyrus blasted through the other side. Amazing how he could run in high heals through mounds of snow and ice. He looked everywhere for a sign of Sans and saw him up on a hill with the girl Sans wanted to talk to.
Quickly Pap hid behind a tall tree to listen. Not to eavesdrop but rather to look out for his brother in case something were to happen to him. They were still out of earshot but he could still read their expressions. It surprised Papyrus to see Sans looking sad to him. Then the fight happened and blocked him out from interfering. All Pap could do was wait and watch as they talked. Sometime after, maybe 30 minutes or so of just waiting Papyrus decided to sit down hoping that they would be done and he could meet this strange girl that liked to run. 30 minutes more and Pap decided that enough was enough. His patients had ran out as he stood and headed up to the hill. He got maybe at the base of the hill that he noticed Sans sitting next to something?
"SANS?... IS.. IS THAT A HUMAN?"
Sans looked down in worry as he quickly tucked Frisk's hood over her face. "What!? Nah bro t-this is just a messy fold up rug." Sans lied as he walked down to his bro's side. Only looking back once to tell her to get inside. He shifted Papyrus to walk with him as they almost turned the corner. Frisk felt a bead of swet drip down her face at being called a "messy rug", but lifted her head a tiny bit to watch them go. "I guess they got away." Sans's voice was heard as she smiled and went into the now open door. "Funny bones." Frisk commented as she shut the door behind her. "Maybe he wasn't so bad after all." Frisk thought as she headed back home. Back to Toriel and Rose.