How would UT/HT Sans and both SwapFell/UnderFell Sans & Papyrus act when a badass looking human comes along? Like the MOST badass looking person to exist, covered in scars, missing a limb or few, tatoos, sharp teeth, a glare that could make UF king Asgore piss himself, a weapon in every pocket, & a constant serious face. Has lived through wars since young, can fight & ends it quick, has high stats, & has killed. Only to find out they're the biggest sweetheart & are extremely gentile.
UT! Sans: at first he’s very worried and doesn’t want you near him or Papyrus. But when he finds out how sweet you actually are, it doesn’t bother him at all. You’re super sweet.
HT! Sans: it doesn’t even phase him. Still talks to you like he would anyone else. I mean, what are you gonna do to him he hasn’t already been through? Oh you’re nice. Cool. Didn’t matter anyways.
UF! Sans: Stays clear of you at all costs. One day you end up talking, he kinda loves you. Weather it’s platonically, or romantically he wants you in his life.
UF! Paps: he wants you as an ally. When he finds out you’re actually a sweetheart he’s like oh. Never mind then. Still would be friends with you, because you’re intimidating though.
SF! Sans: challenges you. When you decline his challenge he starts to stalk you a little, eventually you become friends. He finds out you’re really sweet, and for some reason he wants to protect you? Even though you don’t need that?
SF! Paps: well shit, be my friend? Let’s intimidate people? No, really he wants to ne your friend. Finds out you’re a total sweetheart, so that makes it easier.