If you’re Pedro Pascal’s Joel in “The Last of Us,” you’ve spent decades staving off a zombie apocalypse, battling “clickers” and non-infected guerrilla fighters. Most of your family is dead, and your 19-year-old adopted daughter is now sullen and distant — perhaps she knows you killed a bunch of people to save her and then lied about it. In short, you’ve got issues.

It only makes sense that you’d need to see a therapist. This one happens to treat her patients with tough talk and a glass of whiskey, and her health plan is flexible: she takes weed for payment.

Oh, yes, and you killed her husband.

Of all the developments roiling in Sunday’s season 2 premiere — including the mental evolution of the newly strategic zombies, and the budding romance between Ellie (Bella Ramsey) and Dina (Isabela Merced) — the richest might be the emergence of Gail, the hardened psychotherapist played by Catherine O’Hara. She only gets one dialogue scene, but it’s one of those key sequences that makes the show’s universe relatable to viewers. After all, who doesn’t need to be occasionally told to “say it out loud,” as Gail implores Joel during their session? (For the record, he still hasn’t followed her advice.)

O’Hara gives Gail a steely, seen-it-all demeanor shot through with sadness, vulnerability, and fatalism. When she mentions that Joel murdered her husband, Eugene — we assume he was among the infected — she does so as a means of instruction: If she can talk about this, shouldn’t Joel be able to share about what’s, er, eating him?

She’s a pro. But she’s definitely not Dr. Melfi, the TV shrink played by Lorraine Bracco in “The Sopranos.” Accepting Joel’s payment of a bag of dirt weed, she scoffs: “Shake and stems, what am I, in high school?” When Joel protests that winter isn’t the ideal time to harvest marijuana, she replies that Eugene would “grow buds the size of pine cones, sticky as glue,” even during the coldest months. She says this wistfully, as if it gives her even more reason to miss the man.

It’s easy to see Gail’s potential, not merely for the survivors at the compound in Jackson, Wyo., but also for viewers. Think of the character exposition that might emerge over the coming season, session by session, patient by patient. Ellie, a teenage killing machine, could certainly use a weekly check-in. Maybe she and Joel can even get to the bottom of the chasm between them. First, they’d best work on those gardening skills.