Neil said, defining fannishness potential:
(1) the need for an active suspension of disbelief (pre-requisite of all
SF
and fantasy shows).
I would tend to disagree--I'd say that active suspension is not necessary if the show is internally consistent. Fine, whatever, vampires, hyperspace drive...what drives me round the twist is Episode 3 says the ship can't go over 22 lightyears/minute and in Episode 5 it's cheerfully cruising along at 45...
(2) episodic structure, a succession of closed stories (though not necessarily without a broader story arc to hold the series together).
But Buffy and Angel are very fannish (or at least very fanned, if that's a word) and they are outright soap operas--it's very much assumed that viewers will be aware of detailed past events.
It was tactful of Neil not to mention: (n) Fan has crush, perhaps slightly embarrassing crush for being on the "wrong" person--i.e., second leads seem to have more fen than leads, even though you're "supposed" to root for the lead.
-(Y)