
By its nature, roleplaying in a game environment is most assuredly fanfiction. That's a pretty catch-all term, so really it comes down to what you mean by starting over?
Are you wanting to cast your FC as the main heroes? That works if you want it to; instead of the One True Hero you get a cast of them, similar to conventional FF titles. Do you just want to share in the world? That works fine, too, even if it requires a little more effort from the "Dungeon Master" role to keep plots and things moving along.
If you give us a little more insight into what you're looking to do, someone here can likely provide support for it. Roleplay is pretty malleable.
Are you wanting to cast your FC as the main heroes? That works if you want it to; instead of the One True Hero you get a cast of them, similar to conventional FF titles. Do you just want to share in the world? That works fine, too, even if it requires a little more effort from the "Dungeon Master" role to keep plots and things moving along.
If you give us a little more insight into what you're looking to do, someone here can likely provide support for it. Roleplay is pretty malleable.