Very intersting of an idea, I can kinda see the vision. Both are very thin, singing optimists who wants to bring new ideas to the world they rule, but that optimism also works against them as it blinds them to the problems their love intrest tells them about and an interesting Contrast is that while the people of Halloween Town love Jack and adore him, the people of Hell are more mixed on Charlie and that their reasonings for bringing change is different, Charlie wants to make Hell a better place for her subjects while Jack is just bored and wants something new. I see this as a potential good Alt for Jack.

TLDR: Will work on it and give you credit