Not sure. The main three (male) leads were always played by the same people, that's all I know. I watched the show on an off but wasn't in the fandom (if there was one) so not too familiar.

FW is a show I enjoy but am not crazy for, the way I am for the other scifi shows on my lists (no angsty OTP :D Well, SPN has no OTP either as I am not into Wincest but who cares when you got Dean?). It's still quite fun though and I am annoyed at its lack of DVDs.