I’m watching some old black and white Disney cartoons and they have pluto’s concience represented by a devil pluto and an angel pluto. It’s pretty widely used in cartoons in general. Did Disney make it up or did someone use it before them?
In The Brothers Karamazov, Fyodor Dostoyevsky uses this device for the elder Karamazov brother, Ivan. See Part Four, Book XI, Chapter IX, otherwise known as “The Devil: Ivan’s Nightmare”. However, Dostoyevsky does not have the devil appear in the physical form of Ivan, instead appearing as a common man who gives voice to Ivan’s devilish thoughts. Despite this key difference, the germ of the idea is there for Disney to work with.
We had a similar thread a few weeks ago Good and Evil on your shoulders. Some of the posts may be helpful.