'Little Fires Everywhere': How Reese Witherspoon and Kerry Washington made their scenes 'crackle with tension'

"Little Fires Everywhere" is a study in all kinds of complex relationships, but the one that drives the book (now TV show) is the one between the moms.

In Hulu's adaptation of Celeste Ng's best-selling novel (the first three episodes premiered this week), Reese Witherspoon plays Elena Richardson, who uses a measuring cup when she pours herself wine - only four ounces allowed - and color codes her kids' lunch bags. Kerry Washington plays Mia Warren, an artist who moves from town to town on a whim and can build her daughter a bike from spare parts. Over the course of eight episodes, their lives collide in many profound ways, including being on opposite sides of a heart-wrenching custody battle involving a local couple who adopts a Chinese baby.

The producers knew the Elena-Mia relationship was critical to the show. Witherspoon bought the rights to the book through her production company, Hello Sunshine, so it was a given that she would play Elena. She had always wanted to work with Washington and sent her the script; Washington was a huge fan and signed on. Although Mia's race wasn't specified in the book, Ng pictured her as a working-class white woman. But when producers told her that Washington would play Mia, she said, it was the moment she realized they were truly all on the same page.

"Originally, I wanted to make her a woman of color because the book has issues of class and privilege tied to race ... but I didn't feel like I could adequately imagine a black woman's experience," Ng said. "When they told me they were thinking of casting Kerry, I was thrilled, because that meant they weren't going to shy away from issues (of race), they were going to bring them to the surface. "

Elena and Mia's first interaction isn't even when they're together - Elena calls the police when she sees Mia sleeping in a car in a parking lot with her daughter, Pearl. ("Look, I never normally do something like this, but I would hate to not say something and then have something bad happen," she tells the cops.) A few minutes later, viewers see a police car pull up to the car, and Mia gently shakes her daughter awake: "Hands visible, honey, OK?"

Later, they meet for the first time when Mia tours a duplex that Elena is renting, where Elena can't quite grasp that being an artist is Mia's "real" job: "I feel like that's one of those ideal jobs you see on TV, like a spy, or marine biologist!" Meanwhile, Mia is aghast that in the "Pleasantville"-esque Shaker Heights, Ohio, you will get a ticket if your grass grows an inch too high.

Shortly after, in one of the tensest scenes of the series, Elena asks Mia if she can come work in their house as a maid - or as she quickly clarifies, more of a "house helper, house manager." It's a truly cringeworthy scene, only exemplified by Witherspoon's smug cheerfulness ("You know what felt good? Helping," she boasts to her family later) and Washington's grim-but-not-surprised reaction to Elena's privilege. Ng was in awe watching the dynamics of the characters play out on screen.

"As a person who works with words, it was amazing - I felt like, honestly, watching either of them alone is amazing, but the scenes where they're together crackle with tension because they're both so good, obviously," Ng said. "You see them trying to read each other and their understandings are shifting, and the balance of power shifting between them in every scene. ... (When) Elena says, 'Why don't you come and work for me?' it's like someone jumps off a seesaw."

While their ideas about how to live life seem to clash on every fundamental level and play out with more extreme consequences throughout the series, Ng says that the two women are more similar than people realize.

"People often speak of them as polar opposite, but really, they're two halves of the same coin, this yin-and-yang thing. ... At heart, they share a surprising amount in common. They go all-in on how their lives should be lived," she said. "Elena wants to be this picture-perfect striver with color-coded lunches and calendars. But Mia is just as extreme in her own way, leaning into her art."

Executive producer Liz Tigelaar said that the Elena-Mia scenes were some of the most intense but greatest days on set, as it was like viewing a boxing match. Joshua Jackson, who plays Elena's husband, Bill, agreed - even if he wasn't in a scene, he just enjoyed watching the two actresses together.

"We got to see these two powerhouses go to war," he said. "There's fun in just watching that."