In the AU Storyshift, Sans is Asgore, which means he is the King of the Monsters. He tells less puns than the normal Undertale Sans, and he doesn't know the same characters he does in Undertale. But he does know Papyrus still, who is in the role of Toriel. In Storyshift, you fight King Sans no matter what. In Undertale you only have to fight Sans if you do the Genocide route. Since Asgore and Toriel broke up, Sans doesn't care about Papyrus (Toriel) as much as even though they are still brothers. That makes Sans a Neatral/Genocide/True Pacifist boss. At the end, when you SPARE King Sans, Napstablook (Flowey) still kills him and turns into Omega Napstablook.