IMAGE: Jared Birt

I would not want to be married to Steven Dietz. I’m sure the Seattle playwright is a nice guy and all, but a good number of his 30 or so plays are about marital infidelity. At some point one would have to wonder—why the fixation on cheatin’ spouses?

Dietz’s trademark as a playwright is creating (and destroying) believable relationships. When we meet Michael and Linda Waterman (David Seitz and Gretchen Corbett), the couple whose marriage the playwright plucks apart in Fictionlike a toddler with a butterfly, they are in the midst of a loud, public, very funny throwdown over the most trivial of questions—whether “Piece of My Heart” or “Twist and Shout” is “the greatest rock and roll vocal performance of all time.” This is, we quickly realize, not uncommon for these two. Novelists both, they express their affection in clever, literate barbs.

And they are happy, until Linda is diagnosed with terminal brain cancer and asks Michael if she may read his diaries before she dies. What she finds there—an infuriatingly arrogant account of an affair with the administrator of a writers’ colony (Kerry Ryan)—is shocking, but not entirely for the reasons we expect. There are a lot of secrets here, and they are revealed bit by witty and saddening bit. Corbett gives her best performance in quite a while; she’s been on a tragic kick lately, even in the ostensible comedy A Skull at Connemara, and it’s nice to see her funny, even if she’s funny and dying. Laughing as someone’s world falls apart feels cruel, but coping is coping. Seitz keeps up with her, brash and worried and repentant. I suspect Ryan is not at all what the playwright had in mind for the role—Abby, the writer-wrangler, seems to be conceived as a Bacall type—but her grumpy, impatient delivery works well.

Another of Dietz’s adultery comedies, Becky’s New Car, is playing now at Artists Rep. Fiction is a far better play, feeling more like a completed work than a meandering draft. The infidelities here are sexual but also textual, and the story’s many overlapping lies snap together at the end like an intricate mechanical puzzle. Metaphors are repeated, subtle foreshadowing is revealed, horrible secrets are confessed. Director Brian Weaver makes the most of the play’s opportunities for suspense but doesn’t rush the funny bits. Fiction is the first production of Portland Playhouse’s second season, and the company already appears to be progressing materially as well as artistically: Opening night marked the debut of tiered seating and a lighting system that wasn’t purchased from Home Depot. The beer’s still free.