StoryConciense-Tale is a Undertale AU that introduces Gabriel, Frisk's guardian angel, and Feist, her inner demon. Feist will try to get Frisk to commit Genocide and also try to force her into it by posessing the monsters during the pacifist route.
Gabriel will try to convince Frisk to take the pacifist route, and is the final boss in the Genocide route because he tries to force Frisk to reset it.
He seems to recognize Gabriel, probably because he used to be Chara's Guardian Angel. Otherwise he's the same as Undertale
Gabriel will hide when Toriel saves Frisk, likely because he believes she blames him for what happened to Chara. During the Pacifist run, Feist feeds off her worry for Frisk and posses her, starting her boss battle. Toriel will eventually find Gabriel, and make him promise to protect Frisk.