I've been all over the place, writing-wise, in my Guyver 'fics - and all of my other 'fics, but we're discussing Guyver, here - I've actually created both an OC Guver and an OC Zoalord. I think, for me, the fact that the personalities of the main characters are already so well-established makes me enjoy putting them into different circumstances and seeing how they would react to other people while still essentially remaining themselves.