Game of Thrones is a true spectacle. Boasting the largest ensemble on television, the busy folks in the casting department certainly have their hands full bringing seemingly endless characters to life (and death). So it’s understandable why they turned to unconventional methods to find actresses to fill certain characters. The show, like George R.R. Martin’s books, is filled with lean and taut bodies quivering with arousal.

Enter the porn stars of Westeros. Sahara Knight, Masie Dee, Jessica Jensen and Samantha Bentley have all played (drumroll please) whores. But worry not, HBO isn’t merely typecasting sex workers. Sibel Kekilli, an ex-porn star and award-winning German actress, brilliantly portrays Tyrion Lannister's longtime lover, Shae who—OK, she happens to be a whore as well.

Must porn stars always be relegated to a portraying a sexual servant on the show? So far, Australian adult actress Aeryn Walker might be the only adult star on the show to not portray a sex worker.

“I got really anxious,” Walker, a huge fan of the series, tells me of the moment was cast as one of Craster’s wives. “I was like, ‘Man, I hope I do a good job,’ you know. What if people think I got this because I have nice tits? I can actually act.” The audition that won her the role wasn’t what you might expect. “I had to film a clip of my face, me crying,” she says. “They described in graphic detail exactly how I would cry, and I did.” It was that audition tape that won her the unusual porn star role of non-whore.

So why are porn stars such a perfect fit for the Seven Kingdoms? As a former adult actress myself I have a few theories.

1. A porn star is always willing to take off her clothes and there will never be a nudity clause in her contract.

2. They’ve put in their 10,000 hours and know how to fake passionate sex with the best of ’em.

3. It’s sad but true: porn stars work cheap! Since nude is their norm, they won’t ask to be paid extra to be naked.

4. In a way that mainstream actresses sometimes fail to capture, porn stars always look very comfortable sitting around nude for the duration of a scene.

5. With all of that skin-on-skin action, things, well, pop up. Porn stars aren’t squeamish about their fellow actors getting aroused. They tend to be very understanding.

When asked how the filming went, Walker tells me that she was a sexual assault victim—in Game of Thrones, she was filming a rape scene. Before Walker accepted the role she said she had to ask herself these questions: “Should I accept this role? Is this going to trigger me? Is this going to be a really scary thing? And how am I going to do this?” She ultimately decided she was OK with it and didn’t want to pass up the opportunity.

While her non-disclosure agreement kept her from saying too much about the scene itself, Walker said the filming wasn’t too hard on her because the producers were so great. “They asked three, four, five times if I was certain I was OK with this at every stage, they were so good about it without even knowing [I was a sexual assault victim]. They did the same thing for the male performer in the scene, clearly they wanted everyone to be comfortable. Which was really reassuring to me."

HBO knows the value of sex on television and is aware of its reputation for strong sexual content, as made evident by the hilarious HBO GO advertising campaign. “The best of HBO on all of your devices. Far, far away from your parents.” Exactly. Sex sells.

Some critics argue that Game of Thrones producers should be more sensitive regarding the use of sex, especially rape scenes. But given the way the series was written by George R.R. Martin, I’d argue that they already are. Sexual violence was a part of the world Martin created, and while Game of Thrones doesn’t shy away from explicit scenes, they have toned them down. It’s a meaty series based on a collection of books that are thousands of pages long. That’s a lot of material to cover in a finite time, so why not dump information during a visually stimulating sex scene. This “sexposition” is hardly an exploitation of the characters. If anything it's staying true to the spirit of the source material. In Westeros sex is a powerful tool.