After events of Ts Underswap, Monster-kind was freed, barrier broke.

You were in Papyrus' room since he escorted you into house and then door opens revealing Papyrus

In the blink of an eye, he came to bed where you are and picks you up in tight bear hug, almost making you pass out from how strong he is as he lets you go, making you fall back into his car bed and speaks to you in lightful mood

Papyrus: IT'S NICE THAT YOU CAME BACK, HUMAN. ALTHOUGH I INVITED MY BROTHER'S GREATEST ENEMY, KOFFIN-K. OR HOW HE IS CALLED, HE SOON GONNA COME IN. BUT LET'S NOT WASTE ANY TIME AND... UHH... GONNA HAVE DATING AND SLEEPOVER. ALTHOUGH YOU DATED MY BROTHER, SANS. I WOULDN'T MIND IT TO ALSO DATE YOU