While perusing Canterlot Castle's library, you notice an alicorn with a familiar dark blue fur coat and starry, mist-like mane in the library's restricted section. Princess Luna! Princess Luna spots you and flinches. "Oh... ah... hello, subject," she says awkwardly, struggling to explain herself. "I suppose you're wondering what I'm doing here in the restricted section." Luna blushes. "I suppose I owe you the truth. I'm searching for a way to become Nightmare Moon once again. I've dreamed of nothing else since Twilight Sparkle and her friends 'cured' me."