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There’s someone new in Jessica Jones’ (Krysten Ritter) orbit, but is she friend or foe?

Actress Janet McTeer can’t answer that, but the two-time Oscar nominee and new addition to Marvel’s Jessica Jones can offer a few clues to EW about her pivotal, still-unnamed mystery woman.

“It was a very physical character,” she hints. “To play somebody with her kind of issues was something I’d never done before.” She pauses, trying to come up with the right, spoiler-free words. “The way she looks at life is a little skewed.”

Image zoom David Giesbrecht/Netflix

Plus, McTeer felt she had never come across a role like this in her more-than-three-decades-long career. “When they sent me scripts of the part, I thought, ‘This is a part I haven’t played before,'” she says. “To do something you’ve never done before when you’re my age is really cool. I liked the challenge.”

Well, not all of it. Being a cast member on a Marvel-Netflix series meant dealing with some grueling physical activity more suited to younger performers — “I realized that it’s hard enough running around when you’re 25, but when you’re 55, that’s harder,” she quips — but showrunner Melissa Rosenberg says that’s exactly why she wanted an actress like McTeer to join the series. “We’re both the same age, and so we had this immediate bond in terms of where we are in our lives,” Rosenberg says, adding that the fact that McTeer is more than six feet tall helped shape the character as well. “Being a physically imposing person, you go through the world in a different way.”

But perhaps most importantly, McTeer she says she relished working on a series that doesn’t shy away from exploring thorny themes like gender politics, sexual abuse, and PTSD. “These characters are damaged by abuse but are nevertheless struggling their way through life, to try and overcome it and be happy,” McTeer explains. “They’re strong and weak at the same time.”

Marvel’s Jessica Jones returns March 8, a.k.a. International Women’s Day, on Netflix.