Taking the lead writing duties on any TV series would be daunting.

But stepping into Phoebe Waller-Bridge’s shoes as the lead writer of the Bafta TV-winning Killing Eve is a mammoth task.

Thankfully, Emerald Fennell - the writer given that hefty honour - is no slouch. A friend of Waller-Bridge, Fennell is the author of the children's book series, Shiverton Hall and penned a modern musical re-telling of Cinderella alongside Andrew Lloyd Webber and Tom MacRae.

She’s also an actor in her own right, with roles in Call The Midwife as Patsy Mount, The Danish Girl and soon as Camilla Parker Bowles in the Netflix royal drama, The Crown. 

Before series 2 launched, Fennell told journalists - including BT TV, about her plans for Eve and Villanelle.

***SPOILERS for series 1 ahead***

Were you a fan of season one? And did that give you a fresh perspective on how to approach season two?

I was a huge a fan of season one and I knew a bit about the show and its writing process from Phoebe Waller-Bridge, who is a good friend. However, nothing could have prepared me for how brilliant it was when it came out and, like everyone else, I was obsessed. We actually started writing before season one had come out, so had no idea it was going to be as popular with the world as it is. 

It's difficult to work on something when you're a fan. It's tempting to do what you have secretly dreamed of doing while watching it. I loved the characters so much and Phoebe was brilliant at building such a beautiful and rich world. Going in to it as someone who really loved the characters was heavenly to do.

Emerald Fennell, the lead writer of Killing Eve series 2

Killing Eve is a dance between the hunter and the hunted in season one, how does this dynamic evolve in season two?

Season one was a cat-and-mouse game between Eve and Villanelle, and the dynamic is still there. Eve and Villanelle are two women who cannot help but be in each other’s vortex. The question for season two, is how the power dynamic has changed in their relationship and what it means for these women’s lives.

How does the relationship between Eve and Villanelle evolve in season two?

It's constantly evolving, like all complicated relationships do. All of the hallmarks from last season are still there: the obsession, the fascination and inability to leave it alone, even though it is compromising. What we see this year is that the women are bonded in a sadomasochistic way by an act of extraordinary violence. It's changed their lives massively in different ways and is now more dangerous than it was.

Jodie Comer and Sandra Oh in series 1 of Killing Eve

What are the key story themes that continue and develop in season two?

The theme which was started so beautifully by Phoebe is that of the nature of good and evil: what makes you a good or bad person? What is fascinating about this show is that we have two objectively different characters. It seems clear-cut that Villanelle is an assassin and Eve is this kind, intuitive and empathetic person. But the question of who is good and who is evil isn’t always clear. No matter what Villanelle did, people still loved her, and the darker Eve got, people still felt the same towards her.

It's tempting to do the very spy genre thing and start the season six months later where everyone is healed. However, we wanted to pick up directly after the fallout. For me, the question is how do you get home - both physically and metaphorically - when you have done something so shocking?

I was also interested in looking at their relationship as some sort of addiction and how it is the worst hangover ever. It is the darkest night of the soul where you have done something bad and you have to face yourself. How do you look yourself in the mirror when you do things that you have been taught your whole life not to do? That’s at the core of the whole series.

The Call The Midwife cast at the 2016 TV Choice Awards

Killing Eve is an unusual show about two powerful and deeply imperfect women. Is this helping breathe new life into the spy genre?

Killing Eve is a spy show, but it establishes what it is to be a spy by showing all the mundane, real stuff. So much of the spy stuff that is out there is procedural, whereas in this show we try to shy away from that as it’s less interesting. What is interesting to us is how it compromises your relationships, how you learn to lie to those who are close to you, where you get a coffee if you are working in the MI6 building, and the day-to-day concerns. You rarely see that in the spy genre. It’s showing the ordinary even though you are dealing with extraordinary things.

“It helps if you have a horribly dark sense of humour and a fetish for violence!”
- Emerald Fennell

Do the light-hearted, comedic aspects of the show work to help the dark moments even more disturbing? How do they play off of each other?

The tone of Killing Eve is unique. It's reflected in Phoebe’s writing where there is a dark, savage, rich humour, and it’s a delicate line to tread. You have to be conscious that jokes aren’t too gaggy. The root of it is in the world she has established - things are funny because they are true.

They are also surprising because they are surprising and if people are shocked it's not for plot sake. Eve stabbing Villanelle is a moment of pure instinct. In most shows you would get a big build up for a plot twist like that. But with this show, it just feels like a part of someone’s journey. We are so used to seeing acts of violence on screen that we have forgotten to ask what it would feel like to actually look someone in the face and stab them.

The crucial thing is to be honest and then everything else falls into place. It also helps if you have a horribly dark sense of humour and a fetish for violence!

Killing Eve takes place in cities like Paris, Amsterdam, Rome and London. Do these different cities add a unique flavour to the backdrop of the show?

The locations are so important because where they choose to film in a city is very clever and not often obvious. You won’t have the Arc de Triomphe in Paris but you will have an underpass with some old French graffiti. If you are chasing after someone or running for your life, you are not going to be standing beautifully under the Arc de Triomphe!