Underfell sans or fell or edge Underfell Sans looks very similar to his Undertale counterpart.He doesn't like puns but likes knock knock jokes.he strives to be the cool brother.and he loves mustard and relish.He isn't flustered and isn't always angry, he's just very tired.use gaster blaster and bones attacks.he is kind but he don't like to show that for anyone.he is sometimes rude and cruel.he sometimes flirty.