In the early days of “The Big Bang Theory,” series co-creator Chuck Lorre spoke about the Sheldon character being asexual – or really, just choosing not to participate in the rituals of dating and mating, preoccupied as he was with science and related pastimes, from science fiction to comic books. So the long-awaited, much-ballyhooed consummation of his unorthodox relationship with Amy is either an intriguing evolution or a betrayal of the show’s roots and byproduct of “What do we do to keep things fresh in Season 9?” desperation, depending on one’s point of view.

Frankly, the plot involving Sheldon (Jim Parsons) and Amy (Mayim Bialik) hasn’t been wholly convincing in the build-up, given all the time viewers have spent with him through the years. One of Sheldon’s main qualities, in fact, is his almost complete lack of empathy, his sizable brain so preoccupied with scientific formulae and fictional minutia as to scarcely have enough room to fret about anyone else’s feelings. Perhaps that’s why the revelation that he was thinking about proposing – right before Amy, hurt once too often, broke up with him – came a bit out of left field.

With that as preamble, the episode that paid off that plot (and SPOILER ALERT if you haven’t watched) – combining Sheldon and Amy’s big moment with the opening of “Star Wars: The Force Awakens,” in extremely clever and timely fashion – was better than it had any right to be. Much of that has to do with the gifts of Parsons and Bialik, who have turned their fragile characters into a modern-day “David and Lisa,” having grown to love each other, however improbably, in spite of their respective quirks.

Those qualities came through in the Dec. 17 episode, which (in the most unconvincing wrinkle) saw Sheldon give up his ticket to the “Star Wars” opening in order to spend Amy’s birthday with her, receiving disembodied advice from the spectral TV personality, Arthur (Bob Newhart, now 86, and brilliant as always), who has become his Obi-Wan Kenobi. “Amy’s birthday present will be my genitals,” Sheldon concluded, in an almost clinical manner. (For his part, Arthur wondered why he was never fortunate enough to appear in Angie Dickinson’s bedroom.)

Yet the actual moment (OK, just before the actual moment), juxtaposed with the anticipation surrounding “The Force Awakens,” proved sweet, and almost equally funny. And while Amy’s disheveled hair hinted at a better-than-expected experience, the writing didn’t completely sell out Sheldon’s eccentricities, leaving him content to treat coitus as an annual birthday activity, while clearly harboring more enthusiasm about “Star Wars” than losing his virginity.

The laughs multiplied, moreover, through the near-orgasmic reaction of Sheldon’s friends in the theater, capturing the more extreme quadrants of “Star Wars” fandom – offset by “Star Trek” alum Wil Wheaton joining them to help let some of the air out of the festivities.

At a Hollywood Radio and Television Society event on Dec. 14, Lorre addressed the evolution of the characters, noting how he couldn’t have imagined Sheldon’s arc would lead in this direction. Clearly, “The Big Bang Theory” became a better, more varied show when it elevated its female contingent from one to three, and has even weathered marrying off Leonard (Johnny Galecki) and Penny (Kaley Cuoco), despite clunky moments, this season and last, in servicing their storyline.

Practically speaking, with CBS’ other comedies hardly setting the world on fire, the network has a strong incentive to keep this show as its anchor, meaning “Big Bang’s” future likely hinges on whether (or really, when) the cast will grow tired enough of doing it to be willing to walk away from those Carl Sagan-like checks. And to the writers’ credit, it’s certainly riskier to explore these relationship-driven dimensions than just another “The guys go to the comic-book store” episode.

That said, there’s a long history of sitcom characters hooking up mostly out of sheer creative exhaustion – having run out of things to talk about – and ruining shows in the process. From that perspective, Sheldon’s exchange near the end with Arthur seemingly reflected a desire to avoid that quicksand.

OK, we’ve gotten the whole sex thing out of the way. That was interesting. Time to get back to the Force and the physics.