'IT Chapter Two': Teen Stars Share How They Bonded With Adult Counterparts on Set (Exclusive)

See which teens helped get A-listers hired as adult versions of their characters!

Pennywise the Dancing Clown is back!

ET was on the red carpet at the premiere for IT Chapter Two on Tuesday night in L.A., where the film's teenage cast discussed getting adult versions of their characters this time around.

"You and I did an interview and I said, 'Who do you want to play your adult counterpart?'" ET's Ash Crossan asked Sophie Lillis, aka young Beverly. She responded, "I said Jessica Chastain! Yeah I did!"

It turns out, she got her wish. The acclaimed older actress is stepping into Beverly's shoes as the adult version of Beverly and the rest of the Losers' Club reconvene in Derry, Maine, 27 years after defeating the terrifying clown (played by Bill Skarsgard) in the first film.

"That's sweet. I love that girl," Chastain said in response. "When they were making the first movie, Andy sent me a picture, it was a side-by-side of [Lillis] and me and he just wrote, 'What do you think?' And I was like, 'I see your plans.'"

And Chastain isn't the only star who was seemingly handpicked by the teenage cast to play the adult versions of their characters in the new film. While on the red carpet, comedian Bill Hader admitted that it was Finn Wolfhard who got him the role of adult Richie Rozier.

"Finn Wolfhard basically just got me the job," Hader told ET. "They asked him in an interview who would he like to play and he said me. So, he's really powerful."

And once the cast, both teens and adults, joined forces on set, the teens were able to get to know their grownup counterparts.

"We had some days where we just hung out in his trailer and talked," Wolfhard shared of getting to know Hader during the filming process. "Yeah, I mean, we're good buds."

As the film's final trailer, released in July, showcases, the second and final chapter in the franchise forces Beverly, Richie, Bill (James McAvoy) and the rest of the gang to once again face Pennywise in an effort to stop him from preying on children in their hometown -- leading to all manner of terrifying situations.

Check out more highlights from the red carpet in the clip above.

IT Chapter Two scares its way into theaters on Sept. 6.