As on-screen siblings and ex-child actors, Joey King and Logan Lerman share an uncommon connection. But the Hollywood bond isn’t without its friendly fissures.

Take the term “fiancée,” which King, 24, and Lerman, 32, are debating as they settle in for a recent interview in the Washington Post newsroom. The married King romanticizes the word. The engaged Lerman finds it a tad insufferable. “It’s only in this moment,” King notes. “Then she’ll be your wife and she’ll never be your fiancée again.” But Lerman remains unimpressed. “It’s just the Frenchness of it,” he laments.

Then there’s the topic of spending time away from set with incompatible co-stars. If Lerman isn’t jelling with a scene partner, he makes an effort to link up and build that rapport off-screen. King? Not so much. “If I don’t like someone, I just won’t do it,” she says out of the corner of her mouth. “That’s where the actin’ comes in.”

“Well, I’m just a bad actor,” a chuckling Lerman retorts.

As their affinity suggests, there was no strained camaraderie on the sets of “We Were the Lucky Ones,” the new Hulu limited series. The eight-episode adaptation is based on Georgia Hunter’s 2017 book, which the author wrote about her Jewish ancestors’ scattered quests to survive the Holocaust and reunite on the other side of World War II.

King plays Halina Kurc, a young woman maneuvering to protect her family in German-occupied Poland, while Lerman portrays Hunter’s grandfather, Addy Kurc, an accomplished composer who embarks on a transcontinental escape from Nazi persecution. Although Halina and Addy only briefly share the screen, Hunter has long characterized the brother and sister as the kindred spirits at the core of the five-sibling family. So finding a harmonious pair such as King and Lerman — co-stars from the 2022 movie “Bullet Train” whose career paths have been uncannily aligned — was a stroke of good fortune for the “Lucky Ones” creative team.

“There’s a reason we approached both of them for these parts immediately,” showrunner Erica Lipez says. “These characters are sort of twin souls in the family, and we were looking for two actors who I think embodied both the spirit of those characters and also the connection between them.”

Sit down with Lerman and King, and their distinct energies will quickly become apparent. The levelheaded Lerman tends to stay at a relaxed simmer. The more bubbly King has a knack for chiming in with feisty quips and impassioned observations. Yet there’s also an intrinsic understanding between the actors, who like to pick up each other’s trains of thought and seamlessly steam ahead.

“Bonding with someone over such similar niche life experiences is a very special thing,” King says. “One of the really lovely parts of our friendship is that we both have been through so many very specific experiences that most people haven’t, and that’s both good and bad experiences that we get and can share.”

Born eight years apart, the Southern California natives both got their starts as child actors booking commercials — Lerman for Cabbage Patch Kids, King for Life cereal. Lerman was 8 when he made his big-screen debut in the Revolutionary War epic “The Patriot,” and 13 when he toplined the WB series “Jack & Bobby.” At age 10, King starred opposite Selena Gomez in the children’s book adaptation “Ramona and Beezus”; by the time she was 13, her credits included key roles in “The Dark Knight Rises,” “The Conjuring” and “Crazy, Stupid, Love.”

Reflecting on both actors’ endurance, King posits that while many child performers stumble because they become paralyzingly self-aware, she and Lerman avoided that particular pitfall. “A lot of people lose that thing where they’re not embarrassed,” she says. “I think, ultimately, we both never lost that childlike ability.”

“Life as an actor,” Lerman adds, “is a series of embarrassments and humiliations and things like that. At a certain time, you get used to that.”

The mind-set helped steer King and Lerman to teenage stardom. From 2010 to 2013, Lerman gained recognition as the titular demigod in the Percy Jackson film franchise and a coming-of-age outcast in “The Perks of Being a Wallflower.” After Netflix’s “The Kissing Booth” crowned King as a YA queen in 2018 (and spawned two sequels), she gained critical acclaim and awards recognition a year later for her portrayal of Gypsy Rose Blanchard in the ripped-from-the-headlines limited series “The Act.”

When the “Lucky Ones” creative team, led by Lipez and director Thomas Kail, decided early on to cast Jewish actors as the show’s leads, King quickly came to mind for youngest daughter Halina. The actor, who was raised by a Jewish mother and a Christian father, notes that “the subject of religion in my house wasn’t tense, but it wasn’t great.” Still, King embraced the opportunity to channel that aspect of her identity.

“This is the first time I’ve ever gotten to really play something that was of my heritage,” she says. “As a Jewish woman playing a Jewish woman, I just felt so proud.”

Lerman grew up in a more devout Jewish household. Like King, however, he connected more with Judaism as a culture than a faith. (“I had that fear of God until a certain age,” he says. “Then I was like, ‘I really like the taste of bacon.’”) Although he had already played Jewish characters — in “Hunters,” a Prime Video series about Nazi-thwarting vigilantes that aired from 2020 to 2023, and the 2016 film adaptation of Philip Roth’s “Indignation” — he had resisted projects set in the Holocaust.

That was, until the offer for “Lucky Ones” came through and the source material convinced him to commit.

“I’m very critical of these types of projects,” Lerman says. “My first response is typically, ‘Why do you want to tell this story? Let me see if it’s adding or if it just feels exploitative.’ But this was true and so well researched, and the people were angles on the history that I haven’t seen explored before in film or television. It was immediately clear that this was something I wanted to be a part of.”

For Hunter, watching actors inhabit her family members — the Kurc matriarch and patriarch, their five children, and those siblings’ spouses and offspring — was, unsurprisingly, surreal. When she traveled to Bucharest, Romania, and saw a dialogue-free scene with Lerman on Day One of the four-month shoot, she gleaned the character’s conflicted blend of hope and agony, pictured her grandfather in those dire straits and promptly welled up on set.

“I spent so many years imagining what life was like for them, what their mannerisms were, their quirks were, how they interacted together, and I tried my best to capture that on the page,” Hunter says. “This cast just embodied these relatives so wholly and with so much heart.”

While Lerman’s Addy spends most of the series isolated from his family members, wracked with guilt over their uncertain fates, King’s resourceful Halina bears witness to public massacres and city-razing attacks across Poland. When King needed to center herself before filming the show’s heavier scenes, she would listen to Shoah Foundation interviews with Holocaust survivors and witnesses and remind herself of the role’s responsibility.

“This story is fascinating, and it is a joy and tragedy to watch,” King says. “There were a lot of factors that made it a big challenge, and it always felt very daunting. What I hope for myself is that I continue to do things that feel really scary for me.”