'Mission: Impossible - Dead Reckoning Part One' stars Hayley Atwell and Pom Klementieff helped create their characters: 'I wanted to bring something completely insane'

• Hayley Atwell and Pom Klementieff were hired to "Mission: Impossible" without specific characters in mind.
• Atwell plays chaotic thief Grace, and Klementieff plays ruthless assassin Paris.
• Atwell told Insider her character didn't even get a name until production started.

In "Mission: Impossible - Dead Reckoning," Ethan Hunt (Tom Cruise) returns out of the shadows to take on another world-saving task — but this time, he's fighting a digital threat along with a physical one.

A rogue A.I. that can seemingly predict anybody's future is to blame here, but writer and director Christopher McQuarrie has also thrown in plenty of physical problems for Hunt to take on.

While Esai Morales' Gabriel is the big bad that the IMF has to stop, his henchwoman Paris, played by Pom Klementieff, is "completely insane."  

The "Guardians of the Galaxy" star told Insider that creating Paris was a collaboration between herself, Cruise, and McQuarrie after she joined the film. 

Klementieff recalled: "So, I wanted to bring something completely insane that was really scary for Ethan. So it was just ongoing conversations with Christopher McQuarrie and Tom on how to create the character."

She also noted that she gave input on Paris' costumes because she wanted to do her own stunts in "Dead Reckoning Part One."

"We were thinking about how the character moves, how the clothes move, and then I wanted to do some kicks too because I've been training for years," Klementieff said. "And high kicks, what to wear with that? So a skirt to not be limited in the movements. It took time to create the character and make something like this little monster."

That collaborative spirit was spread across the film. Klementieff's fellow Marvel alumni, Hayley Atwell, later told Insider that she didn't even have a character when she signed on for the sequel. She explained that McQuarrie and Cruise were just looking for the "right person" to join the cast.

"McQ and Tom, during the screen test, said we don't have a character that we're looking for someone to fit into. We find the person that we want to work with," Atwell said. "And then the three of us in real time create that character as we go along and then also seeing what the camera ends up wanting."

The "Doctor Strange" star went on to say that there was plenty of improvisation on set, but her charismatic thief wasn't given a name for quite a while. 

"So we're always kind of throwing out ideas, and then certain bits would be improvised," she said. "I remember when McQ finally christened me and went, 'She's called Grace.'"

"I was like, 'Oh!' and he said, 'It was partly because it was ironic because of who she is,'" Atwell continued. "But he was like, 'It's because you've graciously taken anything we've thrown at you, and you've delivered or are willing to kind of be part of this process.'"