In his last appearance ("Q Who?") Q made a play of wanting to join Picard's crew, but ended up going on and on about the same kind of ideas that had brought humanity to the Continuum's attention to begin with, whether or not it was ready to take the next step. He seemed to come to the reluctant conclusion that humans were not as barbarous as they first appeared, yet also far less capable than they imagined themselves to be (well, meeting the Borg will do that).
This time around he does join the crew, although no one's happy about it. For one, Q has been banished from the Continuum, stripped of his powers and made for all intents and purposes human (by his own choice!) for being unruly. As always, no one's happy to see him, but that hardly proves a challenge, even in Q's diminished capacity.
What's perhaps equally interesting is the B-story, which is a strict contrast to some of the less memorable episodes of the third season to this point, our crew facing a crisis on one of those alien-worlds-of-the-week, yet interacting with it only via viewscreen, maintaining a strict distance between the two, so that or crew can do what it does and the viewer doesn't have to worry too much about the anonymous folk that rarely have any significance anyway. And yes, it's a model that Star Trek uses in earnest from this point forward.
Anyway, the whole point is that there's a crisis the crew is trying to handle, and immediately suspects Q being behind, although all things truly are equal in this instance. Q really has lost his powers and the crisis is most definitely happening. Eventually this puts our impish acquaintance under the care of Data, the android who wishes to become more human, or as far as this episode is concerned the polar opposite of Q.
The third season, strangely enough, took its time getting around to addressing Data, who had previously stolen the entire second season with a single episode, "The Measure of a Man," in which his rights as an individual were put on trial. That would always be a tough act to follow, so perhaps it's not surprising that the creative forces who sought to drastically reshape the whole series approached Data from a distance. He was perhaps the last element that needed any fixing.
Yet "Deja Q" begins a more sober approach, presenting him on more equal terms, less a curiosity than before. It's by no means an episode worth watching if you're only following the arc of Data, but it's a beginning, a new beginning, much as it is for Q. Watching the two together, this is probably the only moment they could have synced up together. You may recall that at first Q was obsessed with Riker, and yet the writers realized perhaps as much as Q that Picard was his true foil, and from this point on, at least in Next Generation, there's very little remaining to separate them. For one moment it's Data, however, who intrigues Q, because Q sees the android not as an artificial being or for his awesome abilities, but very much as Q is at the moment himself, merely an imperfect being, striving to be better than what he is, even if that may seem contradictory.
It's a subtle moment of clarity, and you have to pay attention to catch it. The episode itself doesn't draw too much attention to it, but there it is. Sometimes it's easy to think of Q simply as the annoying pest who happened to be extremely entertaining. Yet the genius of the character was that he was always much more than that. This was the episode to prove it, and it's a great success.
franchise * series * essential * character
John de Lancie
Memory Alpha summary.