Oh they’re aware what’s going on. In ‘Endless Genocide’ epilogue, when you first meet chara in your first Genocide run, they give you the same dialogue and choices you would get in a normal run but, the player is able to break out of their deal, to both keep their soul and continue to reset WITHOUT a true reset. This upsets chara greatly, because they don’t understand how the player could possibly do this, to be in real control and ignore their deal. Every time the player comes back, chara pushes them to stop with their stupid antics and delete their save file, let them take their soul, or not…it might as well be rotten for how much they just love seeing papyrus suffer.