The first season of Killing Eve subverted expectations at every turn, and British intelligence boss Carolyn Martens was no exception. Played to droll perfection by Fiona Shaw, Carolyn’s withering looks and iconic one-liners cemented her as the show’s most surprisingly hilarious character. Shaw spoke to The Ringer about anthropomorphic rats, fuzzy hats, and Killing Eve’s complicated characters.

What was it that attracted you to Killing Eve initially?

I was sent the first script, and I don’t think I’d read anything as exciting in the previous year. It was immediately brilliant. It was so unexpected. The language in it—these incongruous, amazing sentences. Just phenomenal. And I went and had lunch with Phoebe [Waller-Bridge], because I wanted to ask her why she wanted me. As it turns out, she had seen Medea on the West End when she was very young and really liked it. And I thought, “My god, what’s the connection between Medea and Carolyn?” [Laughs] When you see Phoebe, you see that you’re meeting the very edge of now. Her mind thinks in the most wonderful ways. She’s sort of the Dorothy Parker of the 21st century.

Carolyn is such a funny character. Was it easy for you to do that sort of dry, deadpan humor?

No, it wasn’t easy! [Laughs] It was quite hard. Because I kept wanting to allow Carolyn to see the humor of it, and the fun of it is that she can’t. It’s quite a complicated idea. The characters are witty themselves. That’s also what’s so complicated. I mean, Carolyn has a wit, and also the show is witty about her. So it’s double the wit, isn’t it, in the writing?

She has such great lines, like the one about the rat drinking a can of Coke with both hands.

Isn’t that amazing? “I saw a rat drinking from a can of Coke there once.” [Laughs] It’s everything you need to know about the interior of that woman’s mind. The rat line was a favorite, because in it, there’s this sort of black hole—you get swallowed up into the person’s mind. That line doesn’t go anywhere, it doesn’t come from anywhere, and yet it somehow carries huge energy about a random observation. It’s the most marvelous, poetic line, isn’t it? Another great one is when Eve realizes Kenny is her son, but “we haven’t got time for you to react to that right now.” [Laughs] I’ve also really enjoyed playing someone that educated. That’s been great. Someone that powerful and that … still. The stillness of her has been wonderful to portray.

What was it like working with such a talented group of women?

It was just great. From the producers to the cast. And obviously I had much more to do with Sandra [Oh] than everyone else, but I loved working with Kim [Bodnia]. Because, you know, I sort of leave the women in the second half, as it were, and head toward the Russian men. And that was great fun, too. But I very much enjoyed Kim, and talking with him about the seriousness of it. Because even though it’s light, the world of it is quite dark. So we spent a lot of time talking about that. But the girls are just tremendous, and it was lovely having Phoebe come and visit us, and having Sally [Woodward Gentle] as such a hands-on producer. And of course Ms. [Jodie] Comer coming in and out. But I had such great times with Sandra. We would go out to dinner and discuss the peculiarities of the plot, and the following day’s shoot. It was a very happy shoot.

Your character ends up in this ambiguous spot in the finale, and I have to ask—is Carolyn a double agent?

It would ruin it if I told you! Don’t you find that the pleasure of it is in the watching? Even I loved to see it all unfold. Part of the show’s pleasure is that it’s so generous in the human detail. And the plot is part of its importance, but not its only importance, by any means. It’s just … it’s a hoot!

What would you like to see from Carolyn in the second season?

I think the contradiction of a person is what’s being celebrated in Carolyn already. And I just hope that contradiction will continue. That you think you know somebody, and you don’t know them at all. And it’s a celebration of humans, and our potential, and as actors our potential, and I hope that’s just as much a challenge in the next season as it was in the last. I hope there are more surprises about Carolyn around the corner, because I think people are always intrigued by the mysteriousness of somebody, particularly somebody in that role. It’s a little bit like playing Professor Snape in Harry Potter, or like being a psychotherapist. You always want to know what is behind that person’s eyes.

There’s been a lot of discussion about the great costumes on this show, and Carolyn is no exception. That fluffy hat you wear in Russia is amazing.

That hat! I was very keen to wear a hat in Russia. So I brought that in and showed Phoebe de Gaye, who was the costume designer. And she was delighted with it. In a funny way of course, it is a cliché of going to Russia, but it is also a cliché that plays against the cliché. So I loved the hat. And I also had that gorgeous blue dress, in the cocktail lounge. And to my surprise, because a lot of secret service people wear ordinary clothes, I was delighted that Carolyn wears such divine clothing! [Laughs] We had a lovely time hunting for them. There was also a gorgeous dress that I wore in the household dinner scene. Sort of off the shoulder. The costumes have been superb. I know that Jodie’s pink dress has caught everybody’s eye, but I got some gorgeous pieces, in Russia particularly.

Killing Eve shows such a complicated, intimate relationship between women that’s pretty unique to what we’ve seen on screen before. Was that something that drew you to it, besides just the script?

I just loved that it was ... pansexual, as it were. That it wasn’t trapped by any version of unifying forces. I think it’s wonderful. I mean, the obsession that Eve has with Villanelle, of course has a sort of sexual overtone. But it also has a sort of Jungian undertone, doesn’t it? It’s as if they are not complete without the other. So there’s quite a unity at play in it, in a really good—I mean, I don’t want to be technical about it, but in a really good classical sense. There’s a real yin and a yang, or a yang and a yang, or a yin and a yin. They are two sides of something, and in some way, they are incomplete without the other. And that’s a really big theme that allows the series to be so free in the interim. But you never know in those scenes with the two of them, whether it is passion or hatred. You just don’t. It’s a roller coaster of feeling.