When I watch TV comedies, even the good ones, I often find myself wondering what cocktail of personality disorders would be required to make a real human being behave the way sitcom characters do to further stories and jokes. For the most part, those shows don't want their viewers to ask questions like that, treating references to abandonment issues or hyperactivity as just another humor source.

With Casual, which begins its second season today on Hulu, the question of what the hell is wrong with these people isn't obscured subtext, but the whole point of the thing. Not only is its main character, Val (Michaela Watkins) a therapist, but she, brother Alex (Tommy Dewey), and her teenage daughter Laura (Tara Lynne Barr) are each extremely damaged. They're able to vaguely function as human beings when they work together as an unconventional family unit, but on a codependent, self-destructive level that makes the possibility of broadening their circle beyond the three of them all but impossible.

This idea, from the series' creator, Zander Lehmann, is too intrinsically sad for Casual to function as a traditional comedy. The laughs, when they come, are often on the margins — usually involving the befuddled reactions of Nyahsha Hatendi as Leon, a soft-spoken former hook-up of Val's who has, for reasons he doesn't understand, become Alex's best friend — and it's more of a half-hour indie drama in the vein of other recent series like Transparent and Togetherness.

That fundamental truth took a while to reveal itself in Casual's first season, which at first seemed a bit too celebratory of its characters' bad behavior, Alex's in particular. It's one of the reasons it's one of the few Hulu originals done a disservice by the company's more traditional release model; watched one week at a time, Alex might have chased me away. Watched all in a chunk (as I did again with the new season's first six episodes), it becomes more obvious that the characters are emotionally fragile, and that their behavior — say, Laura's sexual attraction to a teacher, or Val hooking up with Alex's girlfriend (or, for that matter, Laura's teacher) — is meant to be dismaying to anyone who isn't living in that house, and that watching them struggle to fix themselves, and each other, is the hook.

Season 2 opens with the trio more or less intact again, but with the dynamics off. Where once it was Alex the manchild tempting Val into breaking bad, now she's the one sabotaging his newfound effort to be physically and emotionally healthy. If Val were somehow able to take herself on as a patient, she might be able to explain that after a lifetime of playing mother figure to Alex (since their hedonist parents showed little interest in raising them), she can't deal with a reality where he doesn't need her. But operating without that degree of self-awareness, she just knows that she doesn't like it and wants Leon to take Alex out drinking, ASAP. Laura and Val have made peace over the teacher incident, but now Laura wants to be home schooled, with Alex preferring to tutor her on late '70s punk bands rather than returning to work at Snooger, the dating site he co-created.

What keeps the series so interesting is how it manages to empathize with the main characters even as it refuses to forgive them their worst. Again and again, the show seems on the verge of pointing its mockery outward — say, when Val attends a meeting with a local group of parents who home school their kids, or when a venture capital firm (headed by Vincent Kartheiser, seamlessly bringing Pete Campbell into the 21st century) buys Snooger — only to pause and acknowledge that our heroes are the ones who are wrong, not the world around them. Val is deeply uncomfortable around the other parents, but admits that they were really nice(*), and while Alex's new boss is both greedy and engaged to Alex's old college flame Sarah (Britt Lower from Man Seeking Woman), Casual seems to understand what Alex doesn't: that Sarah is much better off without him.

(*) There's also some satire of safe space culture that's not the show at its thoughtful best (this is a very easy target), but it's also relatively brief and intermittent.

Little of this would be watchable without the performances of the series' three leads, and Watkins in particular. Val presents as the sanest and most together of the trio, but she often makes the most painful decisions, and through the smallest of changes in expression, Watkins continually shows you how and why Val keeps choosing to go down what she knows to be the wrong path.

Between Casual, Transparent, Flaked, and even the more overtly comic You're the Worst, Lady Dynamite, and BoJack Horseman, there are now so many of these low-fi dramas about depressed Angelenos — often with actors appearing in more than one of them (Watkins has done several memorable guest turns on Transparent) — that there's a danger of confusing the plot of one with another. Katie Aselton from The League turns up early on as a cool shrink whom Val is desperate to befriend, and I spend each of her scenes waiting for the other shoe to drop and for her to turn out to be as secretly awful as her character was in a similar position on Togetherness.

But Casual still stands out among this group because the writing and performances are so specific and so smart that it doesn't feel like a spin-off of six other shows. It deserves, and rewards, careful attention as each character strives to be better and stop making the same stupid mistakes, often getting close before falling back into the usual pattern. There were times in the new episodes where I got particularly frustrated that Val and the others seemed to be going backwards, but then Watkins would flash a nervous smile in an unexpected moment, or Dewey would find some new vulnerable layer beneath Alex's frat boy sociopath exterior, and I'd remember why I wanted to commit to a serious viewing relationship with Casual in the first place.

(**) Though if someone wants to form the Mumblecore Cinematic Universe, where Val can hang out with Maria Bamford and Maura Pfefferman and BoJack, I would not object to that.

Alan Sepinwall may be reached at sepinwall@hitfix.com

Alan Sepinwall has been reviewing television since the mid-'90s, first for Tony Soprano's hometown paper, The Star-Ledger, and now for HitFix. His new book, "TV (The Book)" about the 100 greatest shows of all time, is available now. He can be reached at sepinwall@hitfix.com