The Doctor is ready to return to his universe, leaving his faithful companion and friend Derpy Hooves behind. But Derpy has one wish before he leaves. She wants him to bring Lyra, who has always had a high interest in humans. But Lyra may not be ready to leave her life as a pony behind.
Edit: I'm finding I don't really have much time to work on this, so I'm putting it on hiatus until I have time. Don't worry, it will continue, just not very soon.