If you gender-swapped Peter and Olivia in Fringe, it would be a lot more conventional: tough male FBI agent, female caretaker for mentally ill father. Which is part of why their dynamic pleases me so much, because the swap has already happened (and made the show much more interesting as a result). There are two inter-character tensions that would be different if the genders were changed -- to put it in non-spoiler terms, the histories of what Walter did for/to Peter, and what he did for/to Olivia -- but I don't think the show would change substantially.

And I a) like the idea of Katee Sackhoff as Javert, and b) grin at the choice of what to clarify and what to assume your audience knows. :-)