Though she conceived “Crashing” in her early 20s, it did not air until she was 30 years old, just months before “Fleabag” hit TV. By anyone else’s standards, it was a remarkable television debut, but for her, backward motion is a kind of torture. She is always working to keep one step ahead of her audience. When she is out with Ms. Jones at movies or plays, she has this annoying habit of turning to her friend and whispering precisely what’s about to happen next. Ms. Waller-Bridge constructs her own stories to be “Phoebe-proof,” Ms. Jones says, which makes them “most-people-proof.”
Ms. Waller-Bridge works instinctively, prying open new possibilities and savagely deleting existing plots and characters as she goes. She often consults Ms. Jones, who says that she is “such a perfectionist that it is terrifying.” She regularly chucks out early drafts that blow Ms. Jones away. (Ms. Waller-Bridge has said that she is somewhat less inclined to show her work to her boyfriend, the playwright and director Martin McDonagh).
Her ad hoc process can be a challenge in television, where she has teams of writers working beneath her. Writers may tell her about a scene they wrote that they really loved, and she’ll have to inform them: “Ooh, that person died, I’m really sorry. I killed that person.”
She views casting as the secret second half of the writing process, as if her words aren’t inked until they come out of the actor’s mouth. The final scene of the first season of “Killing Eve,” in which the unlikely spy Eve stabs the master assassin Villanelle, was worked out in Ms. Waller-Bridge’s mother’s kitchen. Sandra Oh, who plays Eve, seized a pencil and jumped on Ms. Waller-Bridge, and they tussled until they lit upon the precise psychosexual energy of the act. “That’s how the moment came,” Ms. Oh says. “Not discussing it over wine.”
Though she is in demand as both a writer and an actress, Ms. Waller-Bridge has no interest in making a star vehicle for herself. She initially considered staking out a role on “Killing Eve,” but she wrote herself out of the story almost by accident. In the novellas, both Villanelle and Eve are in their late 20s, but she made Villanelle an early-20s angel-faced psycho and Eve a 40-something woman with “a big bag and stress eyes,” leaving a perfect gap for Ms. Waller-Bridge herself, who was then “30 years old and not bendy at all.”
Another secretly brilliant move: disappearing into a writing project just as her face was hitting Hollywood billboards.
