Actually, despite the panoply of mythological stock characters in comics, I can't think of anyone who's created a version of the folkloric Jack Frost (rather than just using the name for an entirely new character), so you're being more original than you give yourself credit for.
Cool take on him too -- Chaotic Neutral (aka the asshole alignment) is also a great approach for a fun villain. I like that Jack and Jill are not so much evil as just bored. Nice.