A thought struck me as I watched Supernatural yesterday. How much different would that show be if it was about two sisters instead? How much different would the characters be from how they are now. I think it can be done without changing them too much. I mean, Sigourney Weaver's iconic role in Alien was written for a man and she told them not to change anything - and well, the rest is history.
It's an interesting thought to do a gender reverse to Deana and Samantha with quirks, thoughts and all - nothing changed except gender. Now, if that would happen it would probably feel a bit weird but what if the series was like that to begin with, if it never had been a Dean and Sam - two brothers, then we would have nothing to compare with. If it had been about two sisters, would the series have been equally good and lasted as long? Would the characters be as evolved and full of depth? I don't know, but no matter what, we need more bad ass women on TV.