By James Hibberd
Updated June 05, 2011 at 12:00 PM EDT
Credit: Helen Sloan/HBO

Sunday’s episode of Game of Thrones contained an unexpected treat for fans of George R. R. Martin’s novel when menacing Dotharki horse lord Khal Drogo entered into a life-and-death brawl for leadership of his tribe.

The added scene gave actor Jason Momoa, who’s also pumping up another iconic muscle-bound warrior this summer in the Conan the Barbarian reboot, a chance to show why Drogo is so feared. Showrunners Dan Weiss and David Benioff tell EW this addition to the first season of Thrones was actually Momoa’s idea — but it took awhile for the actor to talk them into it.

“Jason had good ideas about Drogo,” Benioff says. “He had a high batting average of ideas he’d come to us that we liked and ended up using. And one thing he said fairly early on was, ‘I’m supposed to be the baddest man on the planet, I got this long braid because I’ve never lost a fight, and everybody is afraid of me. But nobody sees me fight, and isn’t that kind of lame?'”

The producers argued with the actor — at first.

“We told him, ‘No, it’s good, you’re so badass you don’t have to prove himself. You’re the victor of a thousand battles Jason, go back to your trailer,'” Benioff jokes.

But the more the producers thought about it, the more they realized Momoa was right. “There was something kind of strange with not getting to see this guy do what he does best.”

Adds Weiss: “You have this amazing asset in this actor and it’s a shame not to use it.”

So the producers figured out a way to work in a short fight that was also memorably graphic. “We did it in the Dothraki way, with lots of bloodshed, and it ended up being one of our favorite fights in the season,” Benioff says.

Benioff then wondered about the wisdom of admitting an actor convinced them to change the script. “This is going to come back and bite us on the ass.”