This is how Nightmare Moon speaks with Twilight goes in
[Nightmare Moon brings Twilight to a room]
Nightmare Moon: You're an amazing pony, Twilight. You and I are not so different.
Twilight Sparkle: I'm not like you. You're a villain.
Nightmare Moon: Well, to each her own. I chose my path, you chose the way of the hero. And they found you amusing for a while, the Ponies of Equestria. But the one thing they love more than a hero is to see a hero fail, fall, die trying. In spite of everything you've done for them, eventually they will hate you. Why bother?
Twilight Sparkle: Because it's right.
[Nightmare Moon chuckles]
Nightmare Moon: Here's the real truth. There are lots of different species in this realm. And those teeming masses exist for the sole purpose of lifting the few exceptional ones onto their shoulders. You, me, we're exceptional. [puts a hoof under Twilight's chin] I could squash you like a bug right now. But I'm offering you a choice. Join me. Imagine what we could accomplish together. What we could create. Or we could destroy. Cause the deaths of countless innocents in selfish battle again and again and again until we're both dead. Is that what you want? [looks away] Think about it, Twilight.
[She walks away]
[At Ponyville, Twilight goes back to the Castle of Friendship]
[Twilight thinks about what Nightmare Moon told her]
Nightmare Moon: (voice) In spite of everything you've done for them, eventually they will hate you.
[Twilight looks up]