Just look at her, /pone/. So small, so frail, and so eager to please. You could do anything you wanted to her, so long as she trusted you. Imagine gently coaxing her into a transformation that changeling magic could never undo: the transformation from innocent schoolgirl into your eager cock-slave. She's so vulnerable, it would be so easy.
Just think about it. With the queen dethroned, and the king a soft reformist, she needs a new figure to serve as her everything, as her new parent and her new god. She'd be more than happy to let you take that place if you wanted it, and she'd be more than happy to accept whatever terms of worship you lay out for her. Oh, she'd give out shy, half-hearted little protests at first, but within a week she'd be cheerfully going to classes with your hot human seed still leaking out of her ravaged ovipositor, her hooves bouncing with joy and her wings buzzing with anticipation.
You wouldn't even need her to transform. The thought of this sweet, innocent little nymph needing your cock is far sexier than any false form she could take on to obscure that. So what'll it be? Will you let her eventually be taken by some effeminate nu-changeling "male", who will allow her to grow old uneventfully, her wistful little sighs the only outward sign that this wasn't quite what she wanted? Or will you take her, break her, and breed her the way her biology demands?