This piece contains spoilers about Season 3 of “House of Cards.”

Heather Dunbar rode into Season 3 of “House of Cards” as the one white hat in a sea of grey, but left just as muddled as everyone else. That’s what happens on Beau Willimon’s Netflix series, where manipulation, backstabbing and even outright murder are all part of the very fabric that makes up the U.S. government.

Played by Elizabeth Marvel, “House of Cards” first introduced Dunbar in Season 2 as she investigated Garrett Walker’s involvement in the Raymond Tusk-Xander Feng money laundering scandal. But in Season 3, Dunbar became Frank Underwood’s key opponent in the battle to win the Democratic nomination for the 2016 presidential election. The Huffington Post spoke to Marvel, who said she had “no idea” she’d return for such a major role on the show, about the political figures who inspired Dunbar (the Clintons!) and how she constantly feared getting killed off.

It’s so refreshing to see a strong female character like Heather Dunbar on “House of Cards.” What’s it like to be one of the few truly committed to justice?
It’s fun, but it’s a little nerve-racking. Every time a script would be released, I was just waiting for the assassination attempt or some horrible, dastardly thing to happen to her. But it’s interesting because no one is black and white and no one gets away unscathed. It was very satisfying to play someone who has such clear ideals and goals and was motivated for good.

By the end of Season 3, what are Dunbar’s thoughts on Frank as POTUS?
It’s hard to say. I think her perspective is evolving as she gets deeper into the process. By the end of Season 3, I’m willing to use Claire’s diary [where the truth about her abortion is written] to my advantage. I begin to get my own hands dirty and I also begin to develop an appetite for power myself. Which I think anybody in that position must have, to go through what people go through to achieve power in our American political arena. I think in this day and age, it would have to extend beyond a sense of righteousness and working towards a cause. You have to have a bigger appetite and a bigger ego than that.

Were there any politicians who inspired Heather?
I did a lot of research on Bobby Kennedy for this role. He was who I used as a model. But I realized, trying to put Bobby Kennedy into the current environment, I don’t know what that would look like.

So did you find inspiration from anyone currently in politics?
I looked at Elizabeth Warren a lot. I looked at Bill Clinton a lot for body language and on-camera demeanor. And Hillary [Clinton], of course, for the same reasons. How do you stand tall and strong as a woman while trying to be the smartest woman in the room and try to remain non-threatening? Americans, I think in general, they want a daddy. They’re still not ready to have a mom. [Laughs] So it’s an interesting balancing act for women.

Near the end of the season, Dunbar shifts and says she knows she’s meant to be the president. Is that due to a craving for power or is her motive just about beating Frank?
That’s hard to answer because I have my own ideas, and so much of it is what the writers’ think that is. I don’t know what direction she’s going. But where I was at that point was someone who believes the ends justify the means. In contrast to the current Underwood administration, Heather believes that she would be a righteous leader, a just leader. But also, she has not been tried, she has not been tested. It’s all theoretical to her still. But she has had a taste of what it’s like to have people devote themselves to you and your cause. I think that’s very thrilling, especially when you think your cause is a righteous cause.

When she’s willing to use the journal against Claire, is she desperate to win or is she starting to become corrupt?
I think it’s both, really. The corruption, it’s begun to erode some of her ideals. She also is growing up in the process, she’s having to make decisions that I don’t think she believes would actually have to be made. Now she’s at the big game and it’s a different set of rules. It’s one of those situations where you either get on board or you get out. If this is what it’s going to take to play in this arena she’s gonna do it, because at the end of the day she would make a better leader for the country.

But do you think she knows what Frank is capable of?
That’s a really good question. Does she know? Does she want to admit that? I don’t think so. I think she’s such an idealist and has such deep-rooted respect for the office that I don’t think she’s quite ready yet to admit the full truth of what he’s capable of. But is it it in her consciousness? Yes. Does she get the sense of it? Yes. I think when he says he would fucking kill her, there’s a piece of her that fears for her life, yes.

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Do you envision Dunbar sticking to the platform next season, or do you think she could easily become more corrupt as the campaign continues?
I have no idea what direction they will go. I have my own ideas, and as we know, power corrupts. It can really eat people alive. When you talk through what exactly happened to Howard Dean on the campaign trail, what Bill Clinton must have lived through, what the daily grind of doing what these people have to do. And they can never lose their temper, they can never be tired and they can never slip up or it’s on-camera and it’s everywhere and it’s over. The pressure these people live with for years at a time is incredible. But then the flip side of that is the adoration and the worshipping they receive. How that effects this particular woman who has now realized this whole other potential in herself to become a leader, that could take her many, many directions.

Would you say being on the show has changed your perspective on politics and election season at all?
No. It’s been really interesting and I’ve had the pleasure of meeting some awesome people, like Neal Katyal, who I got to do the Supreme Court episode with. That’s been very cool and certainly talking with the writers and Beau [Willimon] has been fascinating. But my personal relationship to American politics has remained unchanged. I’m skeptical of all of it and always have been. [Laughs]

This interview has been edited and condensed.

Season 3 of “House of Cards” is available on Netflix.