Alrighty! It's time we establish some rules for this universe! 1. In this world, time on the surface doesn't reset. Instead, the world just makes a Frisk when the other completes genocide. 2. The Frisks just vanish after Genocide. 3. Every time a new Frisk falls down, the Underworld resets. 4. There have never been any Pacifist runs. So, Sans is the only one who remembers, but no matter what he does nothing changes. The only way to stop this cycle is to stop a Frisk from falling in and take their place.