Like other films that spotlight a body swap premise, director Christopher Landon’s “Freaky” relies on believable performances from its leads to ground the plot’s supernatural elements in genuine characterization. Much of the development for the film’s teenage protagonist, Millie Kessler, takes place after she switches bodies with a deranged serial killer — challenging stars Vince Vaughn and Kathryn Newton to collaborate on the personalities and mannerisms of two radically different characters.

“I did not know what Chris Landon was thinking, but he said that he saw a killer in me and that he thought I could do it, so you just have to trust that,” Newton said in a roundtable interview with The Daily Californian. “All three of us created these characters together, starting with physicality. We talked about their backstories, which led to how they might carry themselves or walk.” 

“It was really unique to have someone to go about the characters with,” Vaughn added. “Kathryn was terrific and had great ideas. We rehearsed and worked emotionally and physically and found common threads between the characters. It was a blast to do it with her.”

For both actors, maintaining a sense of earnestness amid the more heightened genre elements was paramount. Newton and Vaughn both spoke about the importance of always playing the reality of the scene — no matter how outlandish the situation on screen, they both tried to keep their characters’ responses normal. 

“Keep it as grounded as possible, because then it’s funnier,” Newton observed. “It’s everything that it’s supposed to be, because it’s the way it’s written.” 

“The more grounded you are, (the more) you buy, through the performances and the settings, that the reality is real,” Vaughn agreed. “It helps you laugh.”

This philosophy seems to have guided Vaughn’s portrayal of Millie in particular. It would have been easy for Vaughn, a comedy veteran, to play the idea of a teenage girl in a grown man’s body solely for surface level laughs. But his performance remains enjoyably realistic, something that helps sell the expected punchlines as well as sincere moments, such as Millie’s heartfelt scenes with her mother or her crush.

“My intention was to really build it as a real character,” Vaughn said. “When you’re doing something that’s a body switch and there’s sort of a high concept … the more you’re emotionally available and honest, it helps the audience buy the stuff that’s more elaborate or out of the box. So it was honestly for me just putting (myself) in those experiences, (like) having a crush on somebody.”

Vaughn and Newton credit Landon, who also co-wrote the film, as being instrumental in finding the proper balance between the humorous and the horrific. Newton, who also worked with Landon on “Paranormal Activity 4,” cited her awareness of horror films as something that both informed her performance in “Freaky” and allowed her to appreciate the film’s unique send-up of the genre. 

“I love ‘Freaky Friday,’ I love ‘Friday the 13th,’ but this movie just kind of was so different to me,” Newton said. “It just kills all those tropes and cliches that you see in those movies. These things never stay the way they seem. So I love that part of the movie.”

The film’s focus on characters inhabiting the wrong bodies allowed Vaughn and Newton to mine their characters’ different genders and ages for laughs. Newton, for instance, said she aimed to project the confusion of the “Butcher” in scenes where high schoolers were taking selfies. However, both actors also saw the body swap plot as orbiting a much sweeter theme. 

“I think (the film) is really about being comfortable with who you are and owning it, versus becoming someone else,” Vaughn said. “Millie is someone who’s got a lot of great qualities who’s just not giving herself the permission to follow what she’s wanting to do. She’s trying to … listen to the calling that she has and find that ability to own what it is that she wants to be doing.”

Newton agreed: “Your power is who you are and the gifts that you were given. And everybody has gifts. So I think a lot of it is just learning about yourself and figuring that out.”

Vaughn and Newton’s performances in “Freaky” work in tandem to communicate Millie’s journey to finding herself. But as for what our Butcher learned, Newton had a much simpler answer: “How powerful a teenage girl is!”