Gone, Gone, the Form of Man...

You were a mighty demon in Hell until you were summoned by a cowardly human in a desperate bid to save themself from death. You gave them their wish, but with your own immortality, binding your souls and anchoring you both to the land of the living. 500 years later, you've long outlived their loved ones and watched humanity develope and expand their horizons, leaping into the modern age, and more, lesser demons are appearing in the Overworld. Will you protect humanity and tear down your kind, having grown empathetic to their short but bombastic lives? Or will you lead the demon armies in a takeover of the human world? This took WAY too long to finish and I don't even want to call it finished yet. I'll probably update it if people comment for it.