In last night's Alias, we see yet again that JJ Abrams has no sense of delayed gratification. Not only does Will return (and his jawdropping English impersonation just proves yet again the mistake of keeping Vartan on instead of Bradley Cooper), but in the same episode he dredges up an old contact, goes undercover into the field and kills his "archnemesis" (scare quotes because while the longtime viewers know that Fake Francie killed Real (Boring) Francie, there was no (onscreen) development of Will's enmity towards Fakie in last night's episode; in order to get Will's sudden hate across, we get fed expository dialogue (which, as a rule of thumb, is always less effective than proper characterization/dramatization) -- hoorah!). Not bad for a guy who's been spending the last two years in the Witness Protection program.
Not that I'm necessarily complaining. Having nearly instantaneous payoff (see also: Justin Theroux' two episode stint; the fall of SD-6; the (disastrous) Von-Syd relationship) maximizes the pacing of the series as a whole to a hyperactive level, and in the case of Alias, this sort of kineticism works in its favor. Since story arcs that initially appear to have the promise of longevity can actually come to an abrupt end, it is more or less requisite for the writers to contort the plot constantly to the point of unimaginable mentalism (that's a good thing).