By Kelly Connolly
Updated February 02, 2016 at 12:00 PM EST
Ed Araquel/Fox

Rhys Darby isn’t likely to forget his first collaboration with X-Files writer Darin Morgan anytime soon.

“I’ve never had so much dialogue in my life,” he laughs.

EW caught up with Darby to talk about his turn in “Mulder and Scully Meet the Were-Monster,” the third installment in The X-Files’ six-episode event series. The hour (SPOILERS FROM HERE) turned the classic were-creature storyline on its head, revealing that Darby’s downbeat cell phone salesman, Guy Mann, had been a blissfully ignorant lizard-like creature until a bite from an animal control officer (Kumail Nanjiani) caused him to transform into a man by day — and sometimes by night. Morgan’s dense script gave Darby a lot of heavy lifting to do, and the Flight of the Conchords actor and comedian didn’t want to disappoint.

“It’s kind of like, ‘Okay, I’m on the biggest show in the world, and now I get to do this thing I’ve always dreamt about, and look how many words I’ve got!’” Darby tells EW. “Luckily a lot of it’s sort of voiceover; it’s a monologue. And then [Morgan] said to me, ‘I need you to know it all, because I want you to do it to camera as well.’”

“I’m used to sort of improvising a lot when I do my comedies,” Darby explains. “The writers and directors usually let me go off script, and I knew that wasn’t going to happen on this one, so I had to be a good boy and stand up straight and pull my socks up and do what Darin said.”

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Doing what Morgan said included playing with a dog, “being naked in a forest and then sort of waking up naked and creeping over and stealing someone’s clothes — that was weird,” and acting out a fantasy sex scene with Gillian Anderson’s Dana Scully.

“It was sort of a bit nervous for both of us,” Darby says of filming the exaggerated scene. “But I think I put her at ease. We both had a good laugh.”

But in a twist that sounds straight out of Morgan’s famously existential scripts, Darby says that the laughs turned surreal when prosthetics transformed him into a monster: “I watched myself slowly devolve into something otherworldly. That was certainly off-putting.”

“But then I thought to myself, ‘Well maybe this suits me, you know?’” Darby jokes. “I’ve always felt different to other humans. Finally I’m in my flesh.”