Gaster being the narrator talking to you at the start of the game makes no sense if he's also the "man" appearing everywhere and giving you eggs, who stated he can only talk to you normally [in regular font] from within the hidden prototype Mancountry world. He is somebody who understood the limits of the fictional world he was trapped in and fucked up trying to escape it, and his distorted visage is representative of his everywhere. Also it's just too obvious of somebody like Toby to just play it straight and make him the speaker despite the theme name.

The narrator has to be somebody else. But who?