When fighting sans, what would happen if you continually spare him? As in he is the only spared monster. How would the genocide/neutral route end?
There is a thread abourt this on Steam in which they tried to do this. After a test, the result was:
There was no change at all, Only that he had a different expression, its a glitch.
This is where the thread is: https://steamcommunity.com/app/391540/discussions/0/371919771750167339/
Nothing will happen. The battle will continue as if you healed or ACTed (meaning he won't say anything). The only thing that will change is that, when he tries to SPARE you, he will only say "Friendship... is great, right? Let's quit fighting." (Don't spare him, unless you want to have a bad time)