"There's a lot of history between them, but also a lot of boundaries," says Rhea Seehorn, who plays Kim. "It isn't flirting and sexual in a superficial way. There's a rich friendship and a real respect going back and forth.
"Kim is a conduit for the audience for what they love about him," she adds. "No viewers want to think about how someday, as Saul, he will order hits on people, but we do love that Jimmy colors just outside the lines remarkably well.
"I don't look at each season of 'Better Call Saul' as a countdown to 'Breaking Bad,' thinking: 'We're this much closer to him being Saul.' But in season three you get more glimpses of Saul emerging in Jimmy. This transformation is heartbreaking.
"But he's still a great lawyer," she insists. "And a great thinker."
As "Saul" returned for its third season Monday on AMC (locally at 8 p.m., DirecTV and Dish, and 11 p.m., Comcast), Kim, too, remains a great lawyer, a great thinker and her own breed of enigma. No wonder that, for Seehorn, playing Kim has been a learning process from the start.
Rhea (pronounced "Ray") Seehorn became an actor to learn: "I was obsessed with trying to figure out people psychologically who aren't me," she says, "and walk in their shoes for a while."
In person, her shoes are clearly different from Kim's: stylish boots, not office-suited heels. Her blond hair cascades past her shoulders, freed from Kim's strict ponytail. She flashes a dazzling smile almost never displayed by the meditative Kim, whose introspective bearing strikes a marked contrast to Seehorn's vivacious manner.
"I'm obviously more awkward and dorky in real life," she says. "But it's really fun playing someone cool."
She had logged stage credits on and off Broadway, and supporting roles on the sitcom "Whitney" and the lighthearted drama "Franklin & Bash," when she tried out for "Better Call Saul."
To guard against leaks, the producers were keeping any actual scenes from the show, and even details of the role Seehorn was seeking, tightly under wraps.
Here's Seehorn describing the scene she was given by the casting directors: "I was a policewoman on her way home, exhausted, after her night shift who sees a disturbance in an alley. She thinks it involves a prostitute and drugs, but it turns out to be her own sister, whose tuition she was paying to send her to school in another state!"
As Seehorn later realized, "The scene served as a showcase for traits that could be grafted onto the Kim Wexler character: the workaholic part of Kim; the need to maintain control; dealing with a personal versus a professional relationship. They wanted to see: Can I do this? Can I do that? And we did it many, many ways.
"I had a blast! But it makes you sweat a lot. I wore a sleeveless blouse for all the auditions."
There were three auditions in all, the final one alongside Odenkirk.