Talk:Sans/In Battle/@comment-27604943-20160122080011/@comment-27718464-20160207153936

If you go through a Genocide route, there is no future, as Frisk no longer exists once they sell their soul to Chara. Even if you try a True Pacifist, it's made clear that Chara ends up killing everyone anyway. There is no future for them if you finish a Genocide, which is the only reason Sans fights you. In all other routes, there's still hope for a happy ending if you reset, so he doesn't bother.