Fan-Fiction: Your Universe

I don't know if this idea has been done before (if so, please let me know so as I don't step on any toes around here). 
 
We all know fan fiction is to take a favorite established medium and to substitute your own opinions into it. Well, what if you where given free reign over 1 character, and had to build an entirely new universe around them? Would you start from scratch ala the Ultimate Universe from Marvel Comics? Or would you implant the character in your own universe and have them do kooky things in order to try and get back home? 
 
 
Any character can be used, as long as they're established comic book characters.

@Necrotic_Lycanthrope: I'd write a team book (X Men, Avengers, or JLA) about them all being in separate universes, then a common multiversial threat brings all the Universe's together and the team if formed. (Similar to Crisis on Infinite Earths.

@Necrotic_Lycanthrope: Can I ask for an opinion? I can't decide whether to continue Spider Man: Devil's Deal

or do this:

Could you please read both and let me know which one sounds more appealing/fun to write?

I would reinvent Ms. Marvel, like the Ultimate Universe.

Personally speaking, if i was working with the marvel universe. id have my own super hero/villain and back to hero character. but since this site will try to claim intellectual ownership over such idea's places like this are not always that handy.

I do this with Tim Drake every time I'm bored, don't know why I choose that particular character when he's not even my favorite but whatever the reason it helps pass the time

I would make a what if universe. What if The universes remained joing after the events of JLA avengers. Than i would advance the timeline 10 years to see what sort of characters might emerge. Maybe members of the marvel races join the green lantern corpse. maybe carnage gives birth to a new symbiot whome jumps on the joker. The possibilities would be infinite.

@cliffrice: Thats an awesome idea

Someone besides me should start that :P

I am actually currently writing a fanfiction with this exact premise about Damian Wayne in an alternate universe where superheroes don't exist and he has to find his way home. I am about 8 chapters in and I think it turned out a lot better than I thought if it goes well I may do a sequel.