After Asriel and Chara's death, Instead of running away, Toriel calms Asgore down. But when Asgore tells the monsters the second war is off, Undyne is mad and convinces the monsters to over through Asgore and Toriel (who retreat back to the ruins. Asgore becomes depressed. Undyne becomes ruler. The rule is that all humans must be captured on sight. Sans is to lazy and Papyrus is too nice. So Sans and Pap are fugitives. So they have nothing, They want to escape the underground but if they step one foot outside of Snowdin, they'll be killed. But when Frisk falls down Flowey assists frisk just to get him out of the underground so they can have control over the timeline again. Sans and Pap help them out so they can also escape.