Board Thread:General Discussion/@comment-27907368-20160412010659/@comment-26887879-20160425111636

In a pacifist or genocide route, neither FLOWEY nor sans judges the PC.

In pacifist, FLOWEY reminds them not to kill and sans is missing from Judgement Hall. In genocide, FLOWEY recognizes Chara ("that's a wonderful idea!") and sans is too busy trying to get you to quit to judge you. I mean, he's judging you, but it's not his typical "eyyy, you suck" spiel.

Sans isn't missing from a judgemend hall during Pacifist. He actually compliments you how you never gained any LOVE, but lots of love.

Also if you quit game without saving after Sans finished his Pacifist judgement, and talk to him again (you'll have to repeat this action several times), he'll recognise your time travelling abilities and will eventually give you the keys to his room and secret basement.