Mismatched duos, whether male, female or a mix, are a staple of fiction. But it’s all too easy for plays or movies about them to wax predictable. At first, that might seem to be the case with Florida Studio Theatre’s production of Jen Silverman’s The Roommate.

The duo of this show seems to fit a familiar pattern. Sharon, a nervous middle-aged woman living in Iowa (Jo Twiss), is the naïve, earnest one, welcoming into her home the more earthy and experienced Robyn (Rita Rehn), who’s made her way to the Midwest via the Bronx. Ostensibly, the arrangement is about saving money, but it’s pretty soon clear that Sharon, “retired” from her marriage and with an adult son in New York who seldom returns her calls, is lonely and hopes to find a friend outside of her book club.

Robyn, meanwhile may be less overtly needy, but, with a mysterious past that gradually reveals itself to us, she, like Sharon, is ready for a change. As Sharon says, “I guess everybody wants to start over.”

The first half of The Roommate goes for some fairly obvious laughs, with the audience more than willing to play along. You just know there’s bound to be a bonding pot smoking scene here where Sharon turns on for the first time, and it’s equally likely that Robyn will help set Sharon up with her first online date.

But just when I was getting restless with the jokes, Silverman takes a more unexpected direction, as Sharon begins to cross some lines that surprise even the harder-edged Robyn.  How do the two influence each other, and will the outcome of their transformations be a positive one, or negative?

Thanks to that twist, The Roommate is more interesting, and more complex, than it first appears. Twiss and Rehn both inhabit their roles fully, and while director Gavin Cameron-Webb may hit some of the yuks unnecessarily hard in the early going, the shift of mood in Act II is well handled and, ultimately, poignant.

The Roommate continues through Aug. 7 at FST’s Keating Theatre; for tickets call 366-9000 or go to floridastudiotheatre.org.