Even by lone wolf standards, William Tell stands apart. Or so he tells himself. Out of prison and playing poker for money, Tell breaks his self-imposed isolation when he’s approached by La Linda, a sultry and mysterious backer of gamblers.

“I’m always looking for a good thoroughbred,” La Linda says with a sly smile, before dipping her head to sip a drink. It’s a key moment in Paul Schrader’s “The Card Counter,” a scene between Oscar Isaac and Tiffany Haddish that catalyzes their relationship, one of the film’s two major storylines.

But the dialogue was not in the script. “I pitched that line about seventeen times,” Haddish says with a gleeful laugh. “Paul would say no, but I kept dropping it in.”

Sure, Schrader had cast the comedian seeking the alchemy you get “when you take a natural performer outside their comfort zone,” but he had then spent rehearsals stripping the comedic rhythms and sensibilities from Haddish’s performance.

It was taking away the essence of what earned her renown in “The Carmichael Show,” “Girls Trip” and in her ruthlessly committed comic performance in a supporting role in Eric Andre’s outrageous “Bad Trip,” which she had filmed just before “Card Counter.”

Haddish acknowledges that she’s someone who’s “always searching for the punchline “and when the camera comes on I get my comedy backpack on to make heavy situations lighter. It’s a defense mechanism and I had to turn that off.”

From working with Isaac, Haddish, who is usually physically expressive (she raises her eyebrows, wrinkles her forehead and swivels her neck while saying that to make her point), learned that you could “just be still. I felt vulnerable—all that movement is protection—but it was beautiful and gratifying.”

Still, Haddish insisted that some part of her belonged in La Linda. “She is using her charisma and playing to his ego,” she says of that moment. She respects Schrader’s singular vision for his movies— “It’s refreshing to work with someone who knows exactly what they want; that’s the kind of man I want in my life”—but she knew what her character needed.

Her persistence paid off.

“That line is not one I would have written but Tiffany is so bright and intuitive, and it was her character and it helped her own the role,” Schrader says, adding that not only was Haddish a “firecracker” but that “her work ethic put the rest of us to shame.”

That work ethic, combined with her comedic skills– “As a kid people treat you better when you make them happy”– helped her escape a traumatic childhood in South Central Los Angeles: her mother suffered a brain injury and became violent, she later landed in foster care and also was raped.

Haddish won awards doing Shakespeare monologues in high school competitions, but she discovered stand-up comedy and drama faded into the background.  Still, she loved the idea of working with Schrader. “His movies are dark and beautiful and mysterious, and you think five, seven, eight, ten different things,” she says. “The people are always deeper than what they’re action or their job is.”

Like Schrader’s characters, she knows how to navigate the world without revealing her true self. “I’m wearing a mask right now,” says of her typically buoyant behavior. “I’m in Atlanta working on my next movie but there’s a big part of me that would much rather be in Los Angeles curled up in bed next to my grandma, giving all the healing, loving energy I can so I can keep her for a year or two but that’s not what’s happening right now.”

Haddish briefly choked up while talking about her grandmother, but she quickly returned to her exuberant persona, saying, “Let me put the mask back on now.”