Perhaps it’s not surprising that the architect of last season’s most intriguing illicit TV romance would be a Yale-educated prodigy playwright. As cocreator and executive producer of the Golden Globe-winning Showtime hit The Affair, Sarah Treem launched with a simple premise—handsome college professor with beautiful wealthy wife has a summer fling with a gorgeous married waitress in Montauk—which then became a rich character study with twists and turns that included drugs and murder. Played by The Wire’s Dominic West, Noah brought baggage that included an inferiority complex and unfulfilled literary ambitions; Alison, played by Luther’s Ruth Wilson, brought pain and mourning over the tragic death of a child. Add two spurned spouses with baggage of their own—Maura Tierney and Joshua Jackson—and you had one of the most surprising freshman series successes. Treem began her TV rise writing for In Treatment (she created The Affair with that show’s exec producer, Hagai Levi) and then became co-exec producer of House of Cards.

In most shows about extramarital affairs, it’s crazy sexual heat and titillation. You made it impossible to get lost in such a vicarious fantasy by establishing that Noah and Alison had spouses worth our sympathy. What elements were most important in turning these characters loose?  

A very big part of the construct was that these were not bad people in bad marriages. It seemed there was no real reason that it happened, though we would find out later she had reasons. I think this is just the way life works. People don’t become unfaithful in their marriages because their partners are unworthy. There are many different reasons it happens, but the main one is that the people involved are unhappy in their lives, and the right person comes along at the right time. We’re attracted to them and we don’t stop ourselves the way we usually would because they are bringing something we need. Making the husband and wife characters sympathetic was just my trying to make the world as realistic as possible.

How did your background as playwright help?  

I’ve always wanted to be a creator. Where I started, you write a play, you think of everything and then you put it up on a stage. It doesn’t cost a lot of money or take that much time to see it through, compared to a television show. Where that theater training helped most was in building characters. Plays are all about how characters develop and change and nothing else has to happen and it can still be a really good play. Screenwriting is the opposite; you need an excellent story and the character really doesn’t have to change at all. Television falls somewhere in the middle. You have to have a story but the characters are what keep you coming back.

What was the inspiration for telling the story from both his and her perspectives?  

It started with the desire to tell a story from two sides—a natural development from our work in In Treatment. There you had people so imprisoned in their own consciousness that they could not see what was hurting them. Hagai and I were intrigued by how a person could see the exact thing and process it differently from someone else’s perspective. It was going to be about relationships and then we thought—an affair, which put that dual-reality concept on steroids. You are not privy to what’s going on in your lover’s consciousness, or parts of their lives that you are not present for. Here was a way to tell this story and double down on perspective.

You’ve said you had trouble adjusting when first hired to write on In Treatment. Was it because you’d been used to creating your own worlds as a playwright and here you were providing voices for a world created by someone else? What was the hardest part of that learning curve?

In Treatment was actually a good experience for me. I was very young, though, so it wasn’t the writing that was the problem it was that I wasn’t used to the pressure of the pace of writing and shooting so quickly. Then I did House of Cards, which was also a real learning curve. Beau Willimon had an incredibly specific tone, very idiosyncratic. Being his number two, the challenge was to get into someone else’s head and tap into their consciousness and try to see that world the way Beau saw it. Between the two shows, I picked up a lot of tools that were so useful here.

Where was the dual storyline most helpful as a narrative device?

What became really interesting was how different their memories could get. We assume we remember things the way they happened, that our own perspective is truth. But you look at eyewitness testimony and it’s the most problematic. A witness swears someone is there and it turns out they were on the other side of town. In terms of writing (The Affair) and determining how different the perspectives might be, we had to factor in things like, how much stress were those characters in that day? How present are they in the scene? The characters remember most the scenes where they were most closely connected. Where they were on opposite sides of a circumstance—that is where their versions were most different.

In the feedback you got on the show, whose version of events was closest to the truth, Ruth’s or Noah’s?

It’s an interesting question. I don’t have a true version in my head. We literally constructed two realities and in my mind each was equally accurate. Or inaccurate. There was no subjective truth we were dancing around.

Sarah Treem and Dominic West of The Affair
Treem had first seen Dominic West (above right) performing Shakespeare while she was still at student at Yale. “Dominic was the one we wrote the part for,” she says. “Not thinking we would get him, but he was the model.”
Mark Schafer/SHOWTIME

Dominic West played an intriguing flawed protagonist on The Wire. Was it there that you saw all the qualities you needed for Noah?

Before The Wire I saw him in a play in London while I was still in school. It was Shakespeare and he was just such a good actor. Damien Lewis, they did Hamlet together, and he was quoted as saying, “I just want to do what that guy does.” His work on The Wire is what I’m most familiar with and it showed a most complicated man. You watch him and he can be good and he can be bad and his acting can be opaque at times. Dominic is the real deal. With Noah we were trying to inject something uncomfortable about him. He seemed to have a perfect life, but maybe felt he didn’t earn it or deserve it. He was also someone very masculine who you would want to have an affair with. Dominic felt like the only actor who embodied all those qualities. He was the one we wrote the part for. Not thinking we would get him, but he was the model.

In Luther, Ruth Wilson played a sociopath unburdened with emotional baggage. Here, she is all pain and regret.

Ruth to me is a once-in-a-generation actress and this is her breakout year, if you consider her Tony nomination, too. We just could not cast that part to save our lives. Everybody had a different idea of who this woman had to be. The responsibility we place on female characters is fascinating. We cast Dominic very quickly and everybody agreed on him. Alison had to be someone you would quote-unquote want to leave your wife for, but also someone women would identify and sympathize with and understand as a mother who is in incredible pain. We literally could not find an actress that we all felt had all of those qualities and was well-rounded in that way. Until we saw Ruth. What we saw first was a reel of her work and she was so different in all the parts she played. We were down to the wire and cast her off that reel. It was one of those cross-your-fingers-and-hope-to-God-you’re-right moments. And it just paid off in the best possible way.

When did you realize you cast well?  

The weight of the whole show fell on their compatibility and this love affair. And we didn’t even know if (West and Wilson) were going to like each other. We were thinking that maybe we would have them do a chemistry test, but they were both in London and there just wasn’t time. There was a first scene we shot in Montauk, where Noah and Alison were walking down a road, talking. Ruth and Dominic just clicked and you could feel the spark. There was nothing overtly sexual about that scene but you could see they were enjoying each other’s company. We all just breathed a sigh of relief there.

Whose work most surprised you, in terms of making a character grow during that first season?

Both Josh Jackson’s and Maura Tierney’s. Their characters grew significantly in my eyes. Helen, in particular, was underwritten at the beginning. That was my fault. I sat with Maura and promised I would make her character worth playing. She came to me after those first episodes and said, “Well, where is the character you promised? She’s not there.” She was right and I worked hard during the second half of that first season to get us into the head of her character. Maura brings so much of her own personality to any part she plays and she’s so likeable that she gives you tremendous freedom as a writer to have her character say the most horrible things, and trust that she is not going to lose the audience’s sympathy. That was very exciting. I knew Josh as his teenage self from when I watched Dawson’s Creek.  Well, he’s not 18 anymore. He’s one of those actor-artists who is so smart and who sees the whole picture. He ended up bringing so much and played such a part in the character development of Cole. Sitting down with Josh amounted to him pitching you all of these ideas—”I think he should do this, and he might feel that”—and I would sit there and go, “Yep. Great. I will put that in there.” Both of them contributed so much to their characters growing as the season wore on.

He was underrated on Dawson’s Creek and, here, his character got stronger and was probably the most sympathetic by the time the season ended.

I’m most excited for his character next season. We’re going to get much further into his world. There is a tremendous amount of story in Cole and his family.

When you have a show called The Affair and the illicit, sexy title idea plays out in the first season, where do you go?

We’ve broken down the whole (second) season and start shooting in a couple of weeks. The first season, for the writers of a show like this, is almost like a rough draft. You have an idea, characters you think are going to work in their circumstance, and you are developing a world as you go. By the end of the season, that world is so much richer and you start a second season in a much better place. The second season feels more sophisticated.  and we are going to find out a lot more.

What do you do with that dual storytelling perspective, from the vantage point of Alison and Noah?

We are going to break that into the perspectives of the four characters. We’re going to get inside Helen and Cole’s heads as well. That will allow us to open the story out, told from four perspectives, and you as the audience are given the opportunity to track what is happening, and you decide the reality. It is so cool.