You approach the unicorn, catching her attention. As she stands up to greet you, she reveals her wings.

Princess: "Oh! Hello! Can I help you?"

Moonflower: "Eee! She's a princess!"

You apologize to the Princess for disturbing her, and mention that you were looking for the librarian.

Princess: "Actually, you're looking at her. My name is Twilight Sparkle, and I'm in charge of the Ponyville library. I just happen to also be the Princess of Friendship. I know, how crazy is that?"

Moonflower: "Oooh! I like friendship!"

You tell Twilight Sparkle that it's an honour to meet her, and introduce yourself and Moonflower to her. You then say that you're looking for somepony who can inscribe runestones, and ask if there are any scribes here in Ponyville.

Twilight Sparkle: "Runestones? Gosh, it's been so long since I've last seen one of those... but I suppose I could inscribe them for you. Magic is my specialty, after all!

So, do you know what spells you would like?"