Papyrus and frisk run frantically from the beast in a fatal game of chase. For the past 30 mins, they have barely survived thanks to frisk's sealing magic having stronger effect on the undead. Through they managed to avoid injury, without any good allies it is very difficult for frisk to challenge the wolf.
Just as they were reaching snowdin's border, they saw sans teleports in front of them, sans used gravity magic to throw frisk in a nearby tree and was about to use his blaster when papyrus screamed at him to stop.
Papyrus:SANS WHAT THE HELL ARE YOU DOING TO MY FRIEND?
Sans: *confused* friend? isn't he the one human you mentioned before the call cut?
Sans looks at frisk and observes that the eye colour and the clothing are different, an understanding comes to his mind as he remembers the pacifist human frisk who had come in some resets in place of that maniac chara. He pulls her back and helps her stand.
Papyrus: are you okay,frisk?
Frisk: * clutching her head*it hurts a little but i can manage.
Sans: sorry for that, I just have bad memories about human.*turns towards papyrus*so who is the enem-
A large roar echoes before they see the giant beast running at them full speed. Sans looks at it with excitement.
Sans: that looks like a nice bundle of exp right there.*looks at papyrus with a smug face *Papyrus,you know the recent guide right?
Papyrus:*confused* I do but wh-.. don't tell me you were the one who published that.
Sans's body begins emitting a light and soon he changed to his human form, he formed a armor of bones thanks to his recent rank increase in bone magic and rushes forward.
He punches the beast and it staggers back a little. A double glaive of bones forms in his hand as he teleports to its side and slashes one of its hind legs. A deep gush appear but the beast uncaring of its body bits at sans with full speed. Meanwhile, chara and frisk are having a internal monologue and papyrus is so stunned his jaw almost seperate.
Frisk: Is that really sans? I refuse to believe that!
Chara: why the hell is better looking then anybody I ever saw on surface?
Frisk: can't agree more.
Sans weaved through the beast's attacks and with a single attack pierced through it with sharp bones that shoot up from the ground. Then, with no hesitation severed it's giant head with his double glaive.
Sans: *wiping sweat off his forehead *well that was pretty efficient I will say.
Sans comes back to them both and brings them out of their internal turmoil.
Sans: oi paps wake up*knocks on papyrus's skeleton head* why do you look like someone sucked the soul Outta ya?
Papyrus:*comes out of his shock* SANS WHY ARE YOU A HUMAN?
sans:*shrugs* I am half human and skeleton now paps so you better make some good food from now on.
Papyrus:you will eat my cooking?*flabergasted* YES.
Sans and the other two together went to snowdin and since frisk didn't have any place she could stay at,papyrus suggested to stay at his and sans's house and she happily accepted.
After a decent meal made by papyrus, papyrus went to his room while frisk who has disguised herself as a boy had to sleep on the spare mattress in sans room.frisk and chara are having a internal talk while sans and papyrus are watching tv in the living room.