[3] In the television series, Polastri was born in the U.K., allowing her to hold a British government job, but raised in the U.S., explaining her North American accent.

[5] Eve Polastri is an MI5 security operative whose job as "an intelligence agency grunt" once involved more paper pushing than intrigue,[3] her intellectual curiosity going unrewarded and underemployed by her superiors.

[4][1] Polastri becomes involved in a cat-and-mouse game with the psychopathic hired assassin Villanelle (portrayed by Jodie Comer), the two women becoming mutually obsessed[6] and sharing what has been called a "crackling chemistry... between bitter enemies and would-be lovers".

[3] Agent Polastri tracks assassin Villanelle across Europe, not as hero and villain but as "two broken women whose flaws bind them together in a twisted pas de deux.

Polastri has been described as a competent professional going through "a bizarre, uncontrollable awakening" and as an "awkward, smart, not entirely self-aware woman with an impressive mass of curly hair".

[10] Actor Sandra Oh remarked that Polastri lacks super-spy skills and James Bond gadgets, but has good instincts and general sense, a head on her shoulders and determination.

[3] While characterized as "a highly capable hot mess, the kind of unlikely hero who's always just on the edge of moral ruination", Polastri's determination is said to make up for her lack of guile.

Writer-showrunner Phoebe Waller-Bridge explained that Polastri has a "sense of self-consciousness and guilt" that cripples her—a perfect counterpoint to Villanelle, who, as Ashley Boucher noted in TheWrap, only does things that might bring joy.

"[14] Judy Berman noted in The New York Times that while men in Killing Eve play traditionally female roles, Polastri and Villanelle's characters differ from those in conventional spy thrillers, which almost never cast women as both cat and mouse, both hero and villain.

[7] In this context, series showrunner Phoebe Waller-Bridge added that these particular women "don't even have to see each other to feel each other's presence", their connection being more complex than romantic relationships: "It's sexual, it's intellectual, it's aspirational.

"[4] Matt Zoller Seitz noted in Vulture that Oh's Korean heritage was "refreshingly incidental" to her part, and, like Eve's Canadian accent, is not central to the story but makes the show "feel as if it's been warped in from some future date where colorblind casting is expected".

[15] Fennell claimed to show the killing as "far more honest and weird and distressing than what we expect", adding that "particularly for women, ... we spend so much of our time hiding how we feel, particularly when it comes to sex and anger and all those kinds of dark emotions".