The Instigators director jokes that he was like 'a marriage counselor' for Matt Damon and Casey Affleck

What's it like working on a film where the two leading actors — Matt Damon and Casey Affleck — grew up together and have known each other for over 40 years? For The Instigators director Doug Liman, who previously worked with Damon 20-plus years ago on The Bourne Identity but had never worked with Affleck, it was akin to "meeting the in-laws."

"Matt's always felt like family or like a brother, but I didn't know the Afflecks," Liman tells Entertainment Weekly, referring to longtime Damon pals (and brothers), Ben and Casey. "So, when I was invited into Instigators, there was a thing where it's like, okay, you're meeting the in-laws, and you're meeting the rest of Matt's family, and you're like, whoa, this is pretty crazy — but it's in the best possible way."

It was Damon who first brought his Bourne director the script for The Instigators, which follows two inept criminals — a desperate father (Damon) and ex-con (Affleck) — who go on the run with one of their therapists (Hong Chau) after a heist goes wrong. Affleck and screenwriter Chuck MacLean are credited with penning the script, but just about everyone involved put their own touches on the story. "We're all working on the script," says Liman. "That's the thing, we challenge each other — we don't need a studio to challenge us. We're spending every day trying to make the best possible movie we can make."

Still, this uber-collaborative process between two people who have known each other most of their lives did leave Liman feeling a bit like "a marriage counselor." The Road House director remembers one moment in particular when they were all taking turns editing the script.

"We're passing the script back and forth, and Matt will do a pass, and Casey will do a pass," Liman recalls. "There was a point where it was going back and forth between Matt and Casey, and there's a scene at the beach house where Casey has quite a long monologue, and Matt would do a pass and cut the monologue shorter, and then we'd give it to Casey and Casey would make the monologue longer."

It would go on like this, with Damon making it shorter and Affleck making it longer, until Liman says he realized, "Okay, I'm getting involved in some family dynamics here that have nothing to do with Instigators." Since he had more history with Damon, he went to his Bourne star first to work out a truce.

"I was like, 'Matt, just don't touch the scene anymore. Whatever you're doing is because of your history with Casey and has nothing to do with the movie. Just leave it alone. Let Casey do what he wants to do,'" says Liman, laughing. "So I was like a marriage counselor, the way anytime you meet the in-laws as an outsider, you could be like, 'Okay, you guys clearly have been friends for a long, long time.'"

When EW relays that sentiment to Affleck and Damon in a separate interview, they have a good laugh about it. "Yeah, we go at it sometimes. I mean, maybe in a way that might make other people uncomfortable," Damon says before Affleck interjects, "But not Doug."

Finishing the thought, Damon explains, "Doug is comfortable with discomfort. Doug is also an incredibly blunt person himself in his assessments of things and in his problem-solving, which I've always really loved. I think it puts some actors off because there's a polite kind of diplomacy that everybody's mastered in the movie business about how to talk to people. And Doug just doesn't do that."

"And," he continues, "we don't do that either, particularly with each other — we've known each other for so long. So that underlying trust and love is all there, and so it's never in question. We can just speak freely and try to solve the problems as quickly as we can, but that's really the way Doug operates, too, so he fit right in with us."

Ultimately, that familial bond only benefited the film. Damon and Affleck's characters Rory and Cobby start as strangers but quickly develop the type of brotherly banter the two actors have in real life.

Or, as Liman puts it: "There's some really great stuff like the chemistry that you see on screen — you can't make that up. Matt and Casey genuinely love each other. And by the way, I genuinely love Matt and I genuinely love Casey, and that shows up on screen."

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The Instigators — which also stars Michael Stuhlbarg, Paul Walter Hauser, Ving Rhames, Alfred Molina, Toby Jones, Jack Harlow, and Ron Perlman — streams globally on Apple TV+ on Friday.