After the events of Weirdmaggeddon, Bill Cipher is trapped in his void. He can't get out to the Gravity Falls universes, but he can watch them. One day, while he was bored, Bill ventures out into UNDERTALE, watching genocides and pacifists. He has seen everybody's powers, understanding everything before going in. What happens? Rated PG-13 for future swearing. I DON'T OWN UNDERTALE OR GRAVITY FALLS!