Employment as a “Casual” cast member comes with a free continental breakfast. (Hulu)

The most dysfunctional brother and sister on TV are back for a fourth and final season. Yes, it’s Valerie the divorced therapist and Alex the failed dating website entrepreneur of “Casual,” the Hulu series that drops its final eight episodes Tuesday.

The new season jumps a few years forward. But no worries, Valerie and Alex are as insecure, angsty and charming as ever. They seemingly have it all — brains, good health, good looks, lovely homes — but keep messing up their lives with stunningly poor choices, like that time Valerie slept with daughter Laura’s high school photography teacher (upon whom Laura was crushing) and got caught in the act. The gifted Michaela Watkins wears all the complications of Valerie on her face, radiating melancholy, confusion, sweetness and inexplicable optimism.

As for Alex, he still can’t commit to a woman. Sure, it’s easy to blame his ditzy and neglectful mother (Frances Conroy), but isn’t it time for Alex to man up? The wistful look in actor Tommy Dewey’s eyes shows how his character is a lost little boy at heart.

“Casual” packs an extraordinary amount of plot and wit into each half-hour episode. One key point this season: Laura (Tara Lynne Barr) returns home after two years abroad, with her lover, Tathiana (Lorenza Izzo). “My family is crazy,” Laura tells Tathiana, who replies, “I was expecting way worse.”

Actually, they are pretty unbalanced. And in this new set of episodes, technology adds to their neuroses. Valerie’s dreams are haunted by an Amazon Echo-like device that knows everything about her — and also possesses the secret of happiness. Valerie thinks her phone must know, too: “I’m ready … lay it on me. Because happiness here I come.” The phone replies: “Bluetooth not detected.”

Amid all this high anxiety is a flicker of hope — with a typically offbeat “Casual” twist. Alex has become a doting dad to a winsome little girl, raising her with her mother, Rae (Maya Erskine), whom he hooked up with when she was his Airbnb guest. Alex says he and Rae are “sexually incompatible co-parents who mostly but not exclusively love each other” — which leads Valerie to dryly note, “What you just described is marriage.”