Harry Potter dies before he's destined to when the Dursleys' house is levelled by a gas explosion. He's sent back as a shapeshifter because there's no time for him to settle on a form and, after spending some time in a form based on Hermione, trying to borrow her smarts, ends up deciding to make his new official identity female.

Only the first chapter has been written so far, but it already has quite a bit of potential. (It sort of reminds me of Yuki onna, in a way)

This may or may not end up deserving a "Reversible" tag, depending on what happens in future chapters. "Danielle" can still shapeshift into a male form, but I don't yet know if she will.