It didn’t take long for Park Chan-wook to realize his Sympathizer star Robert Downey Jr. was a kindred spirit. The iconic South Korean filmmaker, known for genre-busting films like Oldboy and Decision to Leave, made his name by toying with tone, smashing together wild humor and brutal violence, and subverting expectations from frame to frame. And when Downey took on the task of playing a bunch of different characters in HBO’s new limited series (premiering April 14), the Oscar-nominated actor too kept everyone on their toes. “I was astounded by how quickly he was able to come up with a very different performance—he’d do a different improv for each and every take,” Park says. “Even when I had a good-enough take, I had to fall back and suppress myself from asking for more. It was unbelievable to see.”

Such unpredictability, it turns out, is precisely what you need to adapt The Sympathizer, Viet Thanh Nguyen’s Pulitzer Prize–winning 2015 novel about an unnamed Vietcong spy–slash–refugee settling into Los Angeles near the end of the Vietnam War. The book took gonzo turns toward different moods and ideas in its exploration of fraught cultural duality and the overwhelming force of Americanism. The South Vietnam–born Nguyen challenged popular narratives of the war, and more broadly, painted a fascinating portrait of a young man caught between two worlds—and far more genres. Some would call the novel “unfilmable;” others might be willing to take risks, honor the text’s spirit, and never get complacent.

Co-showrunner Don McKellar was intimidated by the prospect. In fact, “I had a hard time picturing it actually before Chan-wook’s name was mentioned,” he says. He and Park, Nguyen’s “dream director” for an adaptation, had collaborated in the past and synced up to helm The Sympathizer together. “It’s angry and satiric and very intelligent and also not afraid to tackle big themes—but it’s also very playful in a way that’s sort of surprising for the heavy subject matter,” McKellar says of the book. “Our main strategy was to replicate that voice cinematically by bringing in Park Chan-wook, because he really shares that sensibility. His work has that edge. He can do satire, he can be devastating, but he also has this playfulness and this wit.”

The series hews rather closely to the structure of the book, which was framed as a long confession to a shadowy figure called “The Commandant.” This version emphasizes the notion that this story may have been told under duress, as the novel implied. “Chan-wook has a very restless mind,” McKellar says. “And we wanted that restlessness to be part of the show, an unresolved feeling, which is part of the book too.” This was true even in the way they broke down scripts together. Park would write in Korean and await a literal translation, nervous about how naturally certain chunks of dialogue would cross over. “But having Don, I was free from such worry,” Park says. “He knows my intention very well.”

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For instance, McKellar didn’t balk when Park suggested that, in the director’s words, the book’s “many faces of Western imperialism shared one single body.” While The Sympathizer’s core ensemble beyond the protagonist (referred to as “The Captain” in the series) is mostly Vietnamese—including his best friend Bon (Fred Nguyen Khan), a trained assassin, and his adviser known as The General (Toan Le), the chief of South Vietnam’s National Police—several white characters of varying antagonism jointly represent the American establishment, from a professor who takes The Captain under his wing to a director (“The Auteur”) preparing a gritty war film. In Park’s estimation, one noted actor needed to play all of the parts. Downey topped their wish list, and he said yes, signing on as both star and executive producer (alongside his wife, the veteran producer Susan Downey).

This anchored the project, as any A-lister’s presence would. And for one relatively unknown actor stepping into the role of a lifetime, it raised the stakes beyond what he could’ve imagined.

“What have I gotten myself into?” On his fourth day of shooting, that question was the only thing running through Hoa Xuande’s mind. The Australian-born actor playing The Captain felt overwhelmed, nervous, anxious—“everything,” as he sums it up—once he met Downey for the first time, preparing to shoot a scene with both him and Sandra Oh. Before cameras rolled, though, Downey offered some much needed comfort. “He said words to the effect of, ‘Brother, we’re going to screw this project up together—don’t you worry,’” Xuande recalls with a laugh. “It can be really intimidating when you work with someone like him and you know that he’s going to run circles around you, but he lent this comforting hand on my shoulder and just said, ‘We’re in this together.’”

It’s one of many moments that feel surreal as Xuande looks back at the whirlwind of The Sympathizer. He first sent in an audition tape for The Captain in January of 2022. He took every call back as incremental encouragement: follow-up Zooms, a trip to Korea to privately audition for Park, a meeting in Los Angeles with some of the producers. “It was a lot of time in between not knowing if I was even good enough—a lot of sleepless nights, a lot of racking my brain,” Xuande says. All told, from that first audition, the process took about eight months. In September, he was at home in bed when he was woken up, asked to join another Zoom call, and offered The Sympathizer’s lead role. He felt like he’d won the lottery.

“He’s got to speak Vietnamese, he’s got to speak English, he’s got to be super charming, he’s got to have this reserve and intelligence, he’s got to be emotional, he’s got to be physical—it’s amazingly demanding,” McKellar says of the challenging role. “We went all over the world. Basically anywhere there’s any Vietnamese diaspora, we put feelers out. We got a million responses. But we always knew he was good. We always loved him.” So why the eight-month ordeal? McKellar reiterates, quite fairly: “This is a very demanding part.”

It also gave Xuande, whose parents are from Vietnam, plenty of time to dig deep. He’d actually started reading the book years prior, before the adaptation was ever in his vicinity, and swiftly recommitted to finishing and grappling with it once he landed an audition. “I tried to get an overall perspective about everybody that was involved, especially the Vietnamese people, because their stories aren’t always told when it comes to the conflict,” he says. “And I heard stories from my parents from when they were growing up, about things that they witnessed, encountered—and had to escape from as well.” 

He wasn’t as fluent in Vietnamese as the character, and so was put through “a two-week crash course” that brought him back to kindergarten, working on the alphabet and vowels and pronunciations. “I tackled a lot of complex Vietnamese ideas and words that I don’t even think the average Vietnamese speaker would say,” he says. “I mean, stuff like dialectic materialists.”

The scripts required an actor capable of wild comedy and devastating drama, to say nothing of the elaborate action set pieces. “When you’re tackling a monster of a show and you’re shooting every day for six months, you’re so in the micro of it all—sometimes I was so caught up in the scene that I forgot, ‘Hang on, the bigger picture of this is quite satirical—it’s actually quite funny!’” Xuande says. But Downey, for one, gave the breakout star the space to find his groove: “He always gave me a chance to go again. He would not move on until I was happy with what I was doing. You don’t always meet people who are as giving as that.”

Xuande was also working with a visionary filmmaker in Park—its own learning curve. “He is such a revered auteur, so when his name is associated with the project, you know that it comes with a certain caliber,” the actor says. “I was scared, to be honest—and it took me a while.”

With Park taking on showrunning duties alongside McKellar, he realized it wasn’t feasible to direct every episode, as he did with his last episodic job, AMC’s The Little Drummer Girl; British TV vet Marc Munden and Oscar nominee Fernando Meirelles were then brought on to helm sections. But Park still oversaw the series’ cinematic approach throughout, attempting to balance stylistic cohesion with each director’s idiosyncrasies. “We were very focused on shooting the entire series with consistency and unity,” he says. Park also, of course, set the singular visual template. “There were big fight sequences where Park would say, ‘Oh, by the way, we’re doing this in one shot,’ and Fred, who plays Bon, was like, ‘Fuck, is he serious? I don’t know if I can do that,’” McKellar says. “He really thinks those sequences through. He would always add something more, he would always push it a little farther. And I loved feeding him and egging him on with little ideas.”

The Sympathizer provided a lot of room for egging on—appropriate, given the scope of the project. This thing is bursting with ideas. When Downey met with McKellar for the first time to go over scripts, the actor threw out some “crazy ideas,” as the showrunner remembers it. By no means a conventional thinker, McKellar still wondered how he could ever implement them, and put them on the backburner until he was asked for an update on the revisions by Susan Downey. So, on his star’s recommendation, he tried some things. Some crazy things. Downey approved. “He used his star power to liberate me,” McKellar says. “He liberated all of us to go for it.”