It’s getting a little too soapy at ‘The O.C.’

“I don’t do sarcasm anymore,” Summer (Rachel Bilson) warns Seth (Adam Brody) on an impromptu trip home to tony Newport Beach from a tree-hugging first few weeks at Brown. “I’m post-ironic.”

“You mean earnest?” Seth replies in an exchange from the first episode of “The O.C.’s” fourth season (Fox, 9 p.m. Thursday). He’s befuddled -- and why wouldn’t he be? Straightforwardness has never been the stock in trade of this slick, teen-oriented soap, which has always appeared to be better and more fully realized as a writing exercise than as an actual televised drama.

Unlike, say, “Gilmore Girls,” which has relied on complex, true relationships to anchor its flights-of-fancy dialogue, “The O.C.” has always settled for brute archetypes, preferring a good brood or a zippy exultation to textured emotional interactions. Otherwise, actual feelings might get in the way of a good pop culture zinger or, worse, a sweet tune from a B-list indie rock outfit.

But things have changed in Newport -- Marissa Cooper (Mischa Barton) is dead, killed in a car crash, and five months later her friends are, quite alarmingly, still coping. Out in Providence, R.I., Summer’s rejected shaving her legs and regular pedicures and has all but traded in one neurotic clinger, Seth, for another, the earth tone-clad, didgeridoo-jammin’ Che (Chris Pratt). Taking another road to clarity, Ryan (Benjamin McKenzie), always a masochist at heart, is now only speaking the universal language of fist-against-face.

The upside to Marissa’s death is that it seems to have restored the Cohen family to their rightful places as paragons of nerdily liberal virtue, if only because everyone else is unreasonably disturbed. Their collective undoing last season was, if not wholly credible, still painful to watch, particularly that of Cohen pere et fils -- father Sandy (Peter Gallagher) lost sight of his well-cultivated ideals in attempting to manage the Newport Group, the company owned by his wife’s late father, while son Seth flubbed his application to Brown, thanks to an extended dalliance with marijuana.

But the Cohens are the core, the only thing preventing the show from sliding completely into Daytime Emmy territory. Marissa’s mother, Julie (Melinda Clarke), is still popping a rainbow of pills, and her younger sister Kaitlin (Willa Holland), a new addition to the cast, seems most skilled at elongating her teenage frame for the perusal of others.

In addition to the unsavory plot turns and ham-fisted storytelling-via-lighting, the show has also been reduced to stunt casting -- Steve-O, of “Jackass,” barely keeps a sober face as a shot-downing Marine in the second episode, and Tia Carrere brings myriad meanings to her new title -- dean of discipline at Harbor School -- as if the role were cast by the editors of Maxim. (Additionally, teen R&B; phenom Chris Brown will have a recurring role later this season as a high school classmate of Kaitlin.)

And the things that made “The O.C.” so novel upon its debut in 2003 have, inevitably, become recognizable tropes. When Seth refers to Ryan as looking “strangely like a young Russell Crowe,” it feels less like an internal critique (as it might have two years ago) than a nod to the press.

Furthermore, the choices of soundtrack music have become almost abusively literal -- note the first episode’s recurring use of Placebo’s “Running Up That Hill,” a spooky version of a spooky Kate Bush song by a spooky singer (which inevitably recalls the late Jeff Buckley’s cover of Leonard Cohen’s “Hallelujah” that oozed over the closing montage of the first season’s final episode). Scriptwriters shouldn’t be picketing reality shows -- they should be protesting music supervisors.

Fox has hedged its bets on “The O.C.” somewhat this year, ordering only 16 episodes of this fourth season (which will air opposite “Grey’s Anatomy” and “CSI”).

But there may be reason for optimism on the horizon. By the end of the second episode, Ryan’s back in the petri dish that is the Cohens’ pool house -- sulking, to be sure, but also reined in. And as at the beginning of the series, he’s just a poor kid getting emotionally manipulated and manhandled by rich folk -- the most honestly felt dynamic the show’s ever seen.