Carnivore Incarnate | Michael Langdon

Constance needs someone to save her. Not in a grand, heroic show that proves good can triumph evil, because she's known enough evil to understand that good can never be low down and dirty enough to win. No, what she needs an ill-fated fool that can withstand the blunt force of hellish terror that is young Michael Langdon, and hopefully, survive the ordeal. Luckily for her, you don't have anywhere else to go.

It just so happens that your somewhat genuine attempt to do some good is the catalyst that sets the end of the world in motion.

Or, you become entwined with Satan's golden child and by the time you realize, you're already his.

Also, this was originally a fanfiction that I read on ao3, but the original creator deleted it so this is my best attempt at recreating it.