Nightmare Moon and Daybreaker.

They are the embodiments of the darkness that exists in the hearts of the two head princesses of Equestria. But what if that darkness was brought out intentionally, for a good reason? What if that bond created something even stronger?

Well that's what inspired this story.

(Contains an intentionally overpowered character, violence, and the destruction of a gigantic asteroid. Expect a series of short stories to spawn off of this)