NOTE: Papyrus calls you "kid" and Sans calls you "human". Sans (AU Nickname: Techno): He's extremely energetic, but in truth, his energy is his way of disguising how depressed he is because of the resets. He has a limited knowledge of timelines, only knowing who d!ed, but not why they d!ed, and nothing else. He can read your facial expression, and has KR. However, he's a scientist, now being Undyne's coworker. He takes a lot of rest breaks, but has higher stats. ATK 3, DEF 3, HP 3. He uses his machines in combat. Instead of tacos, he makes his own ketchup brand. Likes to say "BAH HAH HAH!" Sans cannot open his mouth. Prefers not to fight unless ABSOLUTELY NECESSARY. Even then, won't fight to k!ll. Will first spare, then try to make compromise instead. He has 131 IQ. Papyrus (AU Nickname: Zero): He CAN be energetic, but gets easily tired, and because of this, often is lazy, he loves a lot of the things Canon!Papyrus does. He still has that "Everyone can change" demeanor, but knows some people might not want to change. And he's not as naive as the Classic Papyrus is. He zones out often instead of having depression. Papyrus CAN open his mouth, and has an orange tongue. (Think of Swap!Sans' blue one, and you get the point.) Has 20 ATK, 20 DEF, 780 HP.
If anyone wants to ask a question about this AU below, feel free! All the credit goes to me this time, for the AU, and the vectors! Sans' hands are behind his back BTW-