If you’re a fan of Pedro Pascal — the star of the Disney Plus series “The Mandalorian,” and the cover subject of the Oct. 14 issue of Variety — odds are high the first time you learned about the actor was during his run on Season 4 of HBO’s “Game of Thrones.”

Pascal played Oberyn Martell, the cunning and charismatic prince of Dorne who blew into King’s Landing harboring a lethal grudge against the Lannister family, who he blamed for the rape and murder of his sister and her children. He was, quite simply, a badass — renowned both as a warrior, which had earned him the nickname the Red Viper, and as an unabashed lover to women and men alike.

Oberyn was also — SPOILER alert for the biggest TV show of the last 10 years, not to mention the massively popular “A Song of Ice and Fire” novels by George R.R. Martin — doomed. When he agreed to fight the Mountain in a trial by combat on behalf of Tyrion Lannister, Oberyn nearly triumphed, but he ultimately didn’t quite have his head in the game. (Which is to say, he died.)

Pascal had landed the role after he convinced his good friend Sarah Paulson to send his audition to her best friend Amanda Peet, who is married to David Benioff, the “Game of Thrones” showrunner with D.B. (Dan) Weiss for its eight-season run. He brought such charisma and presence to Oberyn that he became one of the biggest breakout actors from the show, launching Pascal’s career to its current heights.

For Benioff, the key to that success is clear.

“He figures out who the character really is and then he portrays that man, scouring off all falsehood,” he told Variety in an email interview for the cover story on Pascal. “Plus, he’s really f—ing handsome.”

In a rare interview, Benioff shared his insights as to how and why he and Weiss cast Pascal, what Pascal’s first day on the set was like and whether he regrets killing Oberyn off.

What were you looking for in an actor to play Oberyn? What did you need him to be able to do for the role to succeed?

That was such a tricky role to cast. Oberyn entered the story mid-stream, but required the swagger of a character who had been sparring with the other players off-screen for years. We were looking for an actor with charisma, sexual energy, physical menace and depth. He had to be seductive to both men and women; he had to be someone the audience could believe as a killer. Oberyn has a core of white-hot rage that motivates him, and we wanted someone who could convey that anger but also be funny, when called upon, and sensitive, when called upon.

When you received Pedro’s first audition for Oberyn, what struck you about him?

First of all, it was an iPhone selfie audition, which was unusual. And this wasn’t one of the new-fangled iPhones with the fancy cameras. It looked like shit; it was shot vertical; the whole thing was very amateurish. Except for the performance, which was intense and believable and just right.

What was Pedro like on the set?

His first day of shooting was a very long two-hander with Peter Dinklage, the scene where Oberyn agrees to serve as Tyrion’s champion. Dan and I were in a different country, working with the other unit, and I remember emailing with Pedro. He was nervous. I was nervous, too, because it was such an important scene and we weren’t there to watch our brand-new cast member in his first scene with No. 1 on the call sheet.

We got the dailies the next morning. Watching those dailies made me happy. I sent Pedro an email, and told him he nailed it. I’m not sure if he believed me, or thought I was just being nice.

Did you anticipate how popular his performance would become with fans? Did you anticipate how popular Pedro would become in the industry? What was it like to witness both unfold?

Once we saw the entire season there was no doubt Pedro was going to be a star. I thought he deserved more recognition, frankly. Was he nominated for any awards? He should have been. But Dan and I were thrilled that we gave Pedro a job that helped his ascent, because he’s an absolute gem of an actor and a man.

Was there ever a moment where you and Dan thought, “Maybe we shouldn’t kill Oberyn?”

Nope. I mean, we love Pedro. And we loved that character. But his death at the hands of the Mountain was one of our favorite brutal killings from George’s books (which feature a few thousand brutal killings, so that’s saying something). Part of the reason people remember Oberyn is because he died so horribly. And if we hadn’t killed him, poor Pedro never could have done “Narcos.” So, it worked out. Not for Oberyn. But for the rest of us.