Milo Ventimiglia and 'Company You Keep' Co-Star Catherine Haena Kim on Their On-Screen Chemistry (Exclusive)

The stars of the freshman ABC heist drama welcomed ET to the set!

Milo Ventimiglia and Catherine Haena Kim are a dynamic duo on ABC's The Company You KeepThe pair light up the screen as Charlie (Ventimiglia), a con man with a secret, and Emma (Kim), an undercover CIA agent, who unexpectedly find themselves falling in love. ET was exclusively on the set of the freshman heist drama, where the leads shared the secret to their undeniable on-screen chemistry. 

"A lot of is communication," Ventimiglia tells ET's Denny Directo during the March set visit, adding that Kim was "100 percent" all in. "She gave herself so much to the character, to the production, to the process. And I thought that was really wonderful. So within that thought, too, is just us checking every detail with each other, speaking a lot, talking about understanding where our individual characters are and where they collectively are [and] where they are outside of each other."

"I think what we built is unique and real and special and I hope people enjoy the journey of Emma and Charlie," he said. 

Kim, whose past TV work includes Ballers, Good Trouble and FBI, credited her scene partner for bringing his A-game day in and day out. "You're only as good as what you're getting," she said. "And he's such a generous scene partner and also producer. He's always checking in."

"He'll see how the light would be just perfect if I just [moved a little]," Kim shared as an example. (Ventimiglia is also an executive producer on Company You Keep.) "He's also in the editing room. So he's always made sure he pulls everybody's best take. Everyone looks good."

The Company You Keep doesn't shy away from the sexiness (and kissing scenes). Ventimiglia and Kim discussed how they brought that real-life friendship to reflect on-screen as well, revealing that they work closely with an intimacy coordinator to make sure every move is just right. But sometimes, it doesn't come without some scrapes and bruises.

"Today, I definitely clotheslined Catherine as we were walking through the choreography," Ventimiglia quipped, adding, "it's all super choreographed." "We have a wonderful intimacy coordinator, Nicole, who communicates with both of us. It is just like you're Ginger Rogers, Fred Astaire. You're dancing, you're orchestrating something and you have a crew and it's a talking scene. Again, communication, understanding what we need to set goals for the scene, what we need to do."

"It's like what happens, we both turn our heads this way and go in, it's broken teeth!" the This Is Us alum joked of crafting their kissing scenes.

It's no secret the majority of the crew on the show came from This Is Us, a fact Ventimiglia seems proud to boast. He's hoping, if the show is lucky enough to get a second season, that some of his castmates will drop by in front of the camera.

"Everybody's pretty busy. Mandy [Moore]'s working and Sterling [K. Brown]'s working and Justin [Hartley] is about to ship off and do his own show for CBS. We'll see," he offered. Ventimiglia expressed his desire to bring Ron Cephas Jones, who played William, mainly so he could work with him more. 

"Because I didn't get a lot of time with him, Ron Cephas Jones," Ventimiglia said. "I always wanted to have stuff with Ron Cephas Jones... just because he's wonderful. Anybody I'll take anybody. Wonderful, talented people." 

"I was gonna say, next season on The Company You Keep, Emma is played by...," Kim began.

"Sterling K. Brown!" Ventimiglia finished off the joke.

The Company You Keep airs Sundays at 10 p.m. ET/PT on ABC.