zarla-s:

I was thinking about Sans’s poison effect (KR) today, and one theory is that KR is directly fueled and/or connected to your evil deeds, so the KR is turned on by all your murdering. If that’s the case though, that means Sans’s threat during your date in a neutral/pacifist run is a little toothless, because if you haven’t been murdering anyone, he’s only going to do one damage. Though he may still have the INV-skip, haha. While it’d fit thematically for him to only be dangerous (or for you to make him dangerous) on a murder run, I think that the KARMA mentioned in his battle is in a more figurative or metaphorical sense than literal and KR/INV-skip is just something he always has.