"Really Rarity, we have more important things to discuss. To put it simply, the Elements of Harmony stripped Nightmare Moon away from Luna, but didn't destroy her, instead locking her remains away in Luna's head, along with most of her memories of being Nightmare Moon. Through a series of improbable events, I ended up being made from those fragments, and also from Luna." Nightmare sighed and rubbed the side of her head irritably, "As I said, it's complicated. Now can we please get onto the important stuff? I hate having to explain all this to ponies."