Speaking as someone who primarily writes OCs, I've found that changing the universe matters less than changing (or keeping) their overall socioeconomic status and key life events as closely as possible.
I used to work really hard, when translating OCs into different 'AU's, to ensure that all those important elements stayed the same, and that effectively it was always the exact same individual just in a different outfit. But more and more, it's a lot of fun to change other significant details. How would a character you love in one iteration change if you dramatically altered their socioeconomic status? If they were drafted in a war? If they'd gotten some disfiguring condition?
It all amounts to playing out thought experiments along the nature vs. nurture debate. I think you'll find that exploring potential differences can be a lot of fun, and give you a better sense of your character's 'true nature', beyond all of the window-dressing of the world or universe.
If you're making your own original universe, I'd just advise that you take care to be thorough enough in your world-building that there never any unanswered questions or loose threads about how your character got to the point at which you're writing them.
Re: ORIGINAL CHARACTERS
I used to work really hard, when translating OCs into different 'AU's, to ensure that all those important elements stayed the same, and that effectively it was always the exact same individual just in a different outfit. But more and more, it's a lot of fun to change other significant details. How would a character you love in one iteration change if you dramatically altered their socioeconomic status? If they were drafted in a war? If they'd gotten some disfiguring condition?
It all amounts to playing out thought experiments along the nature vs. nurture debate. I think you'll find that exploring potential differences can be a lot of fun, and give you a better sense of your character's 'true nature', beyond all of the window-dressing of the world or universe.
If you're making your own original universe, I'd just advise that you take care to be thorough enough in your world-building that there never any unanswered questions or loose threads about how your character got to the point at which you're writing them.