There's a funny thing with female psychopaths in pop culture: they're nearly always called 'femme fatales'. Sharon Stone in Basic Instinct, Rosamund Pike in Gone Girl and Kathryn Turner in Body Heat: these are heartless and violent women who men just can't resist.
Killing Eve's Villanelle, then, who returns to our screens this week, is neither visibly unhinged - like Angelina Jolie's Lisa in Girl, Interrupted - nor a noirish seductress. She's a ruthless killer (who likes "the breathy ones") but loves fancy dress; she's sexually promiscuous but distracted by reminders of her ex-girlfriend and, while cunning, Villanelle is also undeniably endearing.
She's a cuddly, wide-eyed kind of psychopath with an irresistibly dry sense of humour.
But is she believable? As with other psychological conditions - autism and schizophrenia spring to mind - psychopathy has found itself depicted in hackneyed terms on screen. Mark Freestone, the psychologist who consulted on Killing Eve, explains that this is partly because "nobody wants to watch any [real psychopaths], it's not fun for anyone."
A senior lecturer in the centre for psychiatry at Queen Mary University of London, Freestone was brought into the development of the BBC America series in December 2016. At this point, writer Phoebe Waller-Bridge and Luke Jennings, the creator of the novels which inspired Killing Eve, were still thrashing out the first series in a room where Post-It notes read things such as "stabs him in the eye".
"They said, 'We want to write a psychopath but we didn't really know what that means," Freestone recalls. He mined his experience working in Dangerous and Severe Personality Disorder units in prisons from Durham to East London to channel into making Villanelle "true to form and funny".
A case in point: the Season One scene where Villanelle dons a fake beard and workwear to surprise Konstantin, the closest thing she has to a boss, also happened to Freestone. "I had a patient in his early 20s who would always wear tracksuits and immaculate trainers," he explains. "After working with him for about three months, he turned up wearing a shirt, a gilet and corduroy trousers. He'd ordered them through the occupational therapy service. Everyone was like, 'Why are you dressed like Dr Mark?'."
Freestone says that psychopaths "don't know what to do to signal their connection to someone". Hence the outfit change: "It leads to incongruous behaviour - sometimes psychopaths will wrestle someone to show they have some affection or attachment to them."
What further complicated the construction of Killing Eve's anti-hero was the lack of information surrounding female psychopaths. "The problem is, we don't know a lot about it because we've used a male model of psychopathy," explains Luna Centifanti, a senior lecturer in clinical psychology at the University of Liverpool.
Psychopathy emerged in the 1950s after psychiatric tests were made among members of the male prison population. While the Psychopathy Checklist devised by Robert D Hare is theoretically equally applicable to men and women, more recent studies have found that traits of psychopathy differ between the genders.
Callousness and unemotional traits, such as the inability to recognise or understand fear or upset in others, are far more typical of a male psychopath than a female one. Similarly, psychopathic women are more likely to be manipulative and have a grandiose sense of self. Furthermore, in order to fulfil the clinical diagnosis of a psychopath, the patient needs to have a criminal record, which can also affect the gender differences.
For Centifanti, Villanelle exhibits plenty of psychopathic traits - but ones that are typically male. "The writer hit the mark, but only if she was a man," Centifanti says. "Women with psychopathy tend to be quite manipulative, and Villanelle seems to use manipulation to have fun, rather than to get what she wants."
Centifanti adds that Villanelle's hedonistic taste for casual sex is typical of female psychopaths: "Not very loyal and looking for a good time." Similarly, her overconfidence - interpreted as arrogance by others in the show - could be seen as the grandiosity stereotypical of female psychopaths. "She knows that being female gets her certain privileges and having beauty disarms people."
But, crucially, would Centifanti diagnose Villanelle with psychopathy? "To be honest, she seems more like The Terminator," Centifanti laughs. "She just doesn't seem realistic as a human! And I'm not sure I could classify a robot."
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