Talk:Sans/@comment-5284752-20151230021429/@comment-27590739-20160111085736

Some of this rings true. It's actually something I've thought about for quite a while. Sans only ever does 1 damage, so if you had invincibility frames(which means you didn't kill everyone) then he probably couldn't kill you as quickly. I like to think that during the genocide route is the only time he has a good chance of killing you, because it's the only time that you can get hit for every frame(which is the main reason that you will die during that fight, probably). Who knows? KR and the lack of mercy invincibility might not be a Sans-only mechanic, it might even be there if you fight someone else after Sans, but we don't know because there aren't any other fights after him. I think in the screen for where you're about to kill Asgore in the genocide run, there isn't a KR near your HP bar, so maybe KR is unique to Sans, but you don't get hit after that, so maybe you don't get invincibility frames after beating Mettaton NEO(while keeping up the Genocide Run). It'd require some testing, I suppose.

But, this also means that his "Y o u ' d  b e  d e a d  w h e r e  y o u  s t a n d ." line is kind of a bluff, he doesn't have the right "variables" to kill you with a good garuntee, as you still have invincibility frames at your disposal at the point in time you would have the "date". Bottom line, he's proficient with his magic, but very weak, and needs a specific environment to fight with as much efficiency as in his boss fight. That might even be why we don't get a "pacifist" or "neutral" fight with him, it'd be much easier.