At the heart of BBCAmerica’s hit, Killing Eve, is the obsessive relationship between Eve, an MI5 agent portrayed by Sandra Oh, and the psychopathic killer she is tasked with finding, played almost-too-convincingly by Jodie Comer. Dr. Mark Freestone, Senior Lecturer in Psychiatry at Queen Mary University of London, served as the show’s psychiatry consultant, and we couldn’t wait to ask him all about what makes someone like Villanelle tick.

BBCAmerica.com: As a professional, how would you describe/diagnose Villanelle?

Dr. Mark Freestone: Villanelle is what a psychiatrist might call a “primary” psychopath: she sees people as a means to an end, feels no remorse for her actions, lies easily and without hesitation, and relates to other people in a very distorted way. However, unlike most psychopaths of this type, Villanelle is highly impulsive and can behave unpredictably, appearing aggressive and clumsy in situations where most of us would follow a very clear social convention. Some psychologists believe that psychopathic disorder is actually the mind’s way of defending itself against a traumatic upbringing; a mask of sanity laid over a very conflicted, confused and maybe even vulnerable individual.

BBCAmerica.com: If you were conducting the therapy session that took place in Episode 2, what would your takeaway be?

MF: I like to think that the purpose of the therapy session is not to “treat” Villanelle but for the Twelve to be reassured that there’s no sign that she is “decompensating”: that her psychopathic defense remains intact and nothing she is doing is starting to cause the mask to crack.

However, there are clues in some of Villanelle’s reactions that “something is up.” Psychopaths are continually playing games, particularly with people in authority, to try to assert their power and control, and Villanelle throws in a lot of curveballs to taunt the psychiatrist in this scene, but my question would be: why bother? Why pretend not to speak Russian and wear such a ludicrous dress? Psychopaths are not prone to doing anything without an ulterior motive, even if it’s not a conscious one, and I’d be suspicious that this game was masking a deeper, emerging issue, and I would want to know more about that.

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BBCAmerica.com: So, what does happen when you tell a psychopath they’re a psychopath?

MF: In my experience, either they make a big show of being very angry and storm out of the session, or they smile in a slightly unnerving way that suggests “well, I told you so,” and then brag to their fellow prisoners about how psychopathic they are. However, nothing is ever a sure thing with a psychopathic client; I have been threatened with some pretty unspeakable things, and one of my colleagues once had their head smashed against a table for giving some unwelcome news to a psychopath. Your mileage may vary.

BBCAmerica.com: There has been much written about psychopaths and their sexual behavior (sometimes promiscuity). How do you think Villanelle embodies this?

MF: Primary psychopaths tend to view other people as they view clothes: things to be used for as long as they are valuable, then thrown away. This can make them very promiscuous, but they can also fake their way through marriage-like situations if they think they can milk their partner for money, sex or… less salubrious opportunities. Villanelle is too impulsive to keep up the pretense, so sexual partners become highly disposable and very forgettable; perhaps she even hates them for being such easy prey.

BBCAmerica.com: Sociopath or psychopath — people often confuse the two. How would you tell the difference, especially in someone like Villanelle?

MF: A sociopath is someone with an antisocial personality, who can be callous, aggressive and lack empathy, but will also often be quite vulnerable. True, primary psychopaths are far less common, but they are more narcissistic and so less reliant on other people’s perceptions of them, and can use violence and aggression in an instrumental or calculating way, rather than in anger or self-defense. A sociopath wouldn’t survive a week in Villanelle’s job.

A sociopath wouldn’t survive a week in Villanelle’s job.

BBCAmerica.com: What’s the biggest misconception about the word psychopath?

MF: When I started working in forensic mental health, the word used to make me think of someone with a deep, disturbing and cunning intellect like Dr. Hannibal Lecter. The reality is that psychopaths only very, very rarely have the kind of life that allows them to develop intellectual skills and high social, cognitive, or emotional intelligence. Most of them have had terrible upbringings, full of abuse and neglect, and sometimes you almost think, “There but for the grace of God….” Psychopaths are not super-human predators who are immune to fear and other emotions; they are missing something quite fundamental that helps define what makes everyone else human. What we haven’t figured out yet is how to give this back to them, and that is our failing.

BBCAmerica.com: Eve comments that Villanelle is “showing off.” Is this what another psychopath might do? What’s driving that?

MF: Psychopaths, particularly impulsive ones like Villanelle, are very prone to boredom, so will often trying to “spice things up,” even when their job is something based around extreme violence, or one-up their last performance just to remind themselves how wonderful they are. A former client of mine was a great example of this: he set up his own personal bank, funded from the proceeds of crime, to finance his lavish, illicit tastes, and was eventually caught when he seriously abused a prostitute and rather than paying cash, left her a check, which then bounced. She went to the police, he was caught, and the rest is history. But had he paid cash, or even bothered to check his balance beforehand, he might still be free today, which is an unnerving thought. With Villanelle, though, I wonder if the showing off reflects a bit more than just a need for ever greater risk and stimulation, if maybe at some level she is sending a message for the right person to decode that something in her is unravelling.

BBCAmerica.com: Why do you think she’s so attracted to Eve? And vice versa?

MF: I think Eve represents something to Villanelle that she never had; a stable mother figure who takes a deep and genuine interest in her. The fact that Eve wants to capture and prosecute Villanelle, or use her in quite a calculating way to get to her mysterious employers, is not really interesting to Villanelle; she just cares that Eve represents something fascinating and undefinable that she knows she wants, but not how to get it because neither violence or seduction will work in this case.

BBCAmerica.com: How would you diagnose Eve if at all?

MF: Eve at the beginning of the story is a very believable, neurotic British civil servant, and I love how mundane her job seems despite the perceptions of the security service being glamorous. She is very “thin-skinned” and terribly traumatized by the violence she encounters; but then as the series goes by she starts to become calloused to even very extreme acts of violence and mutilation, and there are signs that she despises herself for this. So it’s possible that she has developed a form of post-traumatic stress disorder, but what is so interesting is that this emotional desensitization actually makes her much more like Villanelle.

BBCAmeirca.com: And overall, would love to hear about your experience on Killing Eve overall and working with the team.

MF: I met up with the writing team at Sid Gentle and from my first meeting, I was impressed by how authentically Luke Jennings had captured Villanelle’s psychopathic character in his novels. Phoebe Waller-Bridge wanted to take the character in a more nuanced direction, so the challenge they put to me was how to do this without “copping out” and giving Villanelle a heart of gold or some other cliché that would make her an implausible psychopath. This was a new and fascinating process for me: what stuck out was the sheer volume of ideas that good writers have about their characters, and it was exhausting – but so rewarding – work trying to provide a context for these ideas that would fit with the existing – very limited – scientific understanding of how psychopaths function, and why. I also have quite a black sense of humor – I suppose it comes with the territory – so when I finally saw the finished product I was delighted by how it perfectly captured the unpredictable core of the psychopath: that unnerving mix of seduction and aggression, and what idiots the rest of us look like when trying to deal with it. I’m extremely grateful to Vicky, Henrietta, Sally, Lee and the rest of the team for involving me in such a dark, funny, satisfying project.

Don’t miss the season’s explosive conclusion SUNDAY at 8/7, only on BBC America.