The last time we saw Dexter Morgan, it seemed that his creators were finally killing him off. Starting in 2006, Michael C Hall had played the vigilante serial killer through eight series of Dexter, followed by an apparently fatal reprise in Dexter: New Blood. But not so fast…

In US television, it’s a bold network that kills off a profitable idea, so the story of a sociopath who masquerades as a forensic expert and channels his bloodlust towards slaughtering evil-doers was too rewarding to end.

Next summer, fans can look forward to Hall’s return in Dexter: Resurrection. But first comes a prequel, Dexter: Original Sin, with a younger actor depicting the making of the murderer. “The Dexter universe is expanding in both directions [backward and forward],” explains Clyde Phillips, the show’s original showrunner, who has now returned to the franchise.

Why has Dexter lasted so long? “It’s important to give the audience credit for being smart and attracted to the complexity of it all,” says Phillips, citing Jodie Comer in Killing Eve and Jason Bateman and Laura Linney in Ozark as examples of anti-heroes who charm the audience despite their crimes.

“Michael C Hall’s voiceover is important too – [it is] Dexter’s inner monologue, and [the reason] why we invite a serial killer into our home every week,” he adds. “It brings us his vulnerability, his fears, his process, and it lets us in as he tries to blend into normalcy.”

The prequel takes us back to the start of his grisly path. A 20-year-old Dexter – played by The OA’s Patrick Gibson – joins his father, Harry (Christian Slater in a feat of inspired casting), in the fictional Miami Metro Police Department as a forensics intern. This allows Dexter to indulge his bloodlust while Dad drills him at home in a code to kill master criminals while staying under the radar.

The idea to return to the first kill came from Paramount Co-CEO Chris McCarthy. “Chris had worked on Yellowstone, where they thought to show how all the characters got there,” recalls Phillips. “So, they did 1883, and then 1923, all leading up to what we already know with Yellowstone.”

“Dexter is Paramount’s biggest franchise, and one of the ways to grow is to get those ‘Dexter-Nexters’ – that’s not my phrase, but they’re right.” While the younger cast appeals to a new generation, a prequel also lets longstanding fans delve into the lead character’s psyche, discovering more about what shaped him.

Irish actor Gibson, as the young Dexter, leads a star-studded cast featuring Christina Milian, Patrick Dempsey and Sarah Michelle Gellar. “We got all our first choices,” says a satisfied Phillips.

As a natural chameleon, Gibson has won many varied Stateside roles. He relished the challenge of Dexter: “It’s an unconventional role in the sense that Dexter doesn’t feel anything, and usually the [actor’s]  job is to channel emotions,” he says.

“I was interested in the idea that, although Dexter is an outsider, we can empathise with that. Most of us have experienced that kind of feeling where you’re outside, looking in. Like a lot of people at that time in life, Dexter is trying to understand himself and his place in the world. It’s a defining moment in his life.”

In other words, as well as blending the genres of horror, drama and police procedurals, Original Sin contains a coming-of-age element. As a 20-year-old trying to fit in, we see Dexter take on challenges like attending a dance and double-dating, all with the show’s deliciously dark humour that lifts what otherwise might be a weighty watch.

Narration is still provided by Michael C Hall. He passed on to Gibson his knowledge about the character before shooting began in June. Gibson says: “I spent a lot of time watching the eight seasons, especially the first, as that’s the closest link we have to Original Sin. But nobody knows Dexter like Michael C Hall. He said Dexter was relatable because every interaction he has is an act. As humans, we do that a lot. We’re all different around different people, and we wear a lot of masks.

“But Michael also gave me permission to make it my own. So even though I studied Dexter’s exterior manifestation, it needed to be an essence rather than a complete impression because Michael was so comfortable and free in the role.”

Gibson used a dialect coach to perfect his young Dexter - to impressive effect. Uncannily, he adopted key mannerisms: head tilts, wry smiles, dead-eyed feigning of emotion. 

Filming for the first series continued until the end of November, just days before the December launch. It was cutting it fine but, with “a generous budget” and Phillips at the helm, the production was a well-oiled machine.

Phillips was the showrunner for the four first Emmy-winning seasons, after which he returned from LA to his New York home. “I realised I was working for a life I wasn’t living,” he says. As well as working on Original Sin, he is overseeing Resurrection. How does he manage the workload?

“I have the bandwidth of an elephant, and I don’t get flustered. I delegate and only hire people to whom I can delegate. If something big and gnarly comes along, I’ll deal with it, but usually I just have other people deal with it until it gets to me.”

Such as? “The most difficult decision is killing off an actor, like when we killed Rita (Julie Benz), Dexter’s wife, at the end of season four. That was a really hard thing to do.”

To create Original Sin, Phillips, who was a showrunner on Nurse Jackie, used a tried-and-trusted process. It began with a writers room and plenty of whiteboards. “I write mystery novels too, and it’s the same in that we start with the ending and build towards it.

“Anything can happen between the beginning and the end, and in the writers room we have a board called ‘NPO’ – No Particular Order – where we write scenes we’d like to see: a subway crash; this character falls in love; a building explodes. About a third of them make it into the show, but they also trigger other events. For example, if you have a subway crash, it’s because they’re running from something.”

Once the scripts are complete, he hands over to his directors, Michael Lehmann and Monica Raymund, and production designer and long-time collaborator Eric Weiler, who helped create the aesthetics of the two eras in which the action happens: 1991 (with student-era Dexter) and 1973 (when Harry meets Dexter’s mother).

“Everything is different in those eras –  you can imagine how big the computers were. The music and cultural references are completely different too,” says Phillips.

Following Resurrection, there are rumours about a spin-off focusing on Dexter’s son, Harrison, and there’s every chance we could return to Dexter’s murderous youth. Phillips says: “Obviously, the network is going to wait to see how Original Sin performs. We in the writers room think it’s going to perform magnificently, so we’ve been noodling out some ideas and growth for Dexter. He’ll only be 21, after all.”

That’s plenty more time to make a killing – or several.

Dexter: Original Sin is streaming now on Paramount+