Sadie Sink finds moments of humor as she unleashes the rage in ‘The Whale’

Sadie Sink remembers crying and screaming in the backseat of the car as her mom drove her older brother to a theater audition. Why did he get to do it but she didn’t? It wasn’t fair. “I begged my mom to let me audition,” said Sink in a recent phone interview. “I was 8.” Finally her mom relented. She had to get special permission because Sadie was two years too young. It didn’t matter. She got the part.

Chalk one up for Mama Sink, who made the right call all those years ago in Brenham, the southeast Texas town where Sadie grew up. Today, Sink, 20, is generating Oscar buzz for her role in “The Whale,” in which she plays the rage-fueled teen daughter of Brendan Fraser’s morbidly obese online English teacher, Charlie. She’s a fixture on Netflix’s hit sci-fi/horror series “Stranger Things,” playing the tough and fiery Max Mayfield, one of an ensemble of adolescents sucked into a morass of monsters and demons. She’ll soon star with Eric Bana in the drama “Berlin Nobody,” about a psychologist investigating a cult.

Right now she’s focused on the double whirlwind of promoting “The Whale,” directed by Darren Aronofsky (“Black Swan”), and preparing for the final season of “Stranger Things,” which will shoot next year. Like her Max character, Sink’s character in “The Whale,” Ellie, has a no-holds-barred approach to life, an attitude that insists you best get out of her way.

“Ellie is definitely a tough pill to swallow,” Sink says. “But I think, hopefully, by the end of the movie, you kind of get into her brain a little bit more and begin to understand where she’s coming from. At least, that’s what I hope.”

If Ellie is abrasive, she has her reasons. Her dad, Charlie (Fraser), in love with another man, left her and her mother when Ellie was a child. Charlie has since eaten his way into near immobility and toward an early grave. When Ellie reenters her father’s life it’s with both guns blazing. Deeply resentful of his absence, with no qualms about commenting on his appearance (created with the use of a fat suit), Ellie is the prodigal daughter with a monster chip on her shoulder. And Charlie isn’t the only target of her wrath. She also takes pleasure in tormenting a local missionary (Ty Simpkins) who can’t seem to stay away from Charlie’s apartment, where Charlie’s best friend (fellow Oscar contender Hong Chau) handles him with tough love, and Ellie seems to skip the love part entirely.

“She’s definitely angry,” Sink says. “But I think it’s really just this immense amount of pain that she’s in that obviously started from a young age when Charlie left her. Over time, this pain and confusion that she’s felt has just manifested into this rage and cruelty.” But Ellie is so complete in her hostility, and Sink is so invested in the character, that humor starts to creep in from the edges. “Oh yeah, it’s funny,” Sink says. “She’s brutally honest.” Some audiences see the humor; when “The Whale” played at the Toronto International Film Festival in September, viewers laughed freely. But when it premiered at the Venice Film Festival right before, only a few were noticeably amused.

For Sink, the big draw was Aronofsky. She was already a fan of his work, and she’s a bigger one after working on “The Whale.”

Aronofsky, working from a script by Samuel D. Hunter (who adapted his own play), put the cast through extensive rehearsals, a rare experience for film or TV. “He kind of treated it as a play, as if we were a theater company,” Sink says. This approach really spoke to Sink, a former theater kid who would like to return to the footlights soon.

“Not only is he a great visual director, but he just really knows how to work with actors,” she says. “And the rehearsal period — the way he handled it and the way he worked on our characters with us — was just really, really helpful. By the time we got to the actual set, and by the time we were shooting, we knew the material so well, and the characters so well, that now we could just play.”

Aronofsky says the pleasure was all his.

“Sadie is as precise as a surgeon’s scalpel,” he says in an email. “She’s a firecracker of emotion and a complete professional.”

Sink is grateful to the film’s star, Fraser. He’s the comeback story of this awards season and the frontrunner at the moment to take home the Oscar, which would be his first. The scenes between Fraser and Sink, fraught with simmering tension, are the most powerful of the film.

“He’s so unbelievably patient, and, especially given the circumstances that he was under, he’s so generous as a team partner,” Sink says. “It’s a very tricky dynamic that the two of them have because they really don’t know each other. But at the same time, they really do. Charlie knows Ellie better than she knows herself, or anyone in her life ever has or will.”