Deku as Dust Sans

Chapter 7

He starts walking to the door of the ruins. Once he arrives he knocks on the door and waits for a reply. Toriel arrives to the door and says "Who's there, and what do you need?" Toriel is confused about how someone knows that there are people in the ruins. Izuku replies "I need to gain entry into the ruins please. There is a killer on the loose inside the ruins." Toriel pushes open the door and sees Izuku standing there. "Come in." She says and gestures for him to enter. "Thank you." Izuku said to Toriel.

Time skip~

Frisk walks through the ruins encountering very few monsters. They reach the Toreil's house, once they enter they notice it sits empty. Going down the stairs they are greeted with the sight of Izuku talking to Toreil. Izuku pulls the knife out of his pocket. Toriel is shocked and says "There was no killer, it was you! Your the killer!" Izuku slashes Toriel with the knife, then Toriel turns to dust. Chara tells Frisk "Hey he just stole our EXP! Go after him and hurry!" Izuku turns around and sees Frisk standing there. He mumbles "Sh*t they're already here." He tries to think of a plan, but ends up teleporting back to Snowdin to deal with Papyrus.

Time skip~

Frisk continues walking towards Snowdin, encountering very few monsters like in the ruins. Once Frisk enters the town, it is empty not even a single person in sight. They walk towards the edge of town and see Izuku attacking Papyrus. Izuku puts Frisk in a cage of bones. He tells Papyrus "I'm sorry Papyrus but I won't let the human hurt you again. Besides it's better for me to kill you instead of the human." Papyrus tries to convince Izuku that there might be another way. "There is no other way Paps." Izuku says with a tear in his eye. Papyrus tells him "It's okay Sans, I believe in you." Izuku lands his final attack and Papyrus turns to dust.