Since Ros isn't a part of the novels, can you explain how you joined the show?
I was supposed to be in one scene in the pilot, the scene she has with Tyrion in the brothel. Just after they got the greenlight, I got an email from David [Benioff] and Dan [Weiss] and they said, "We love your character, we really like what you did. Would you consider coming back if we wrote you in?" So they kept sending me scenes and it went from there. It progressed naturally as they were writing the season.
Did not being a character from the books put you at a disadvantage? How much of the story did you know?
For David and Dan, it gave them the liberty to use her and write her in as they need her. I read as far as Book 3 ('A Storm of Swords'), so I didn't spoil too much for the story for myself. I think if my character had been in the book, I wouldn't have read them because I wouldn't have wanted to know.
For the fans, some love her because she's not in the books and because she's fresh and brings a different element in. But lots of hard-core book fans... they hate her.
Ros has had some memorable scenes—with Theon in Season 1, telling him to get a wife; in Littlefinger's brothel. Do you have a favorite?
Scenes that I did with Theon are the ones I enjoyed shooting the most. Alfie [Allen] and I work so well together; he's such an easy actor to work with. We just clicked when we were on set. I look back at those scenes and I am proud of them. Ros takes no bullshit but she knows how to play guys. Theon is an upstart, he's so gobby and arrogant. They work perfectly together because they have that great dynamic, that push-pull.
I also like the scenes with Varys, in Episodes 304 and 110. There's a similarity in their characters: They're both trying to make the best of where they came from and they're both definitely climbers, as we've learned. Shooting the scene in Season 2 where I have to beat the other prostitute, and the scene with the baby killing were the hardest two for me.
Ros managed to gain the confidence of both Varys and Littlefinger. What is about her that made them trust her?
Everyone thinks she has lower expectations. I think people underestimate her because she's not someone who's trying to marry the king or steal the throne. She's on a different level. But she is so clever at being a woman. She knows how to use her feminine wiles to gain trust, so people have that confidence in her, but they're underestimating how ambitious she is.