Next month, Audible will release the recorded version of John Scalzi’s upcoming novel Head On, a sequel to his 2014 thriller Lock In. Like Lock In — but unlike most audio editions — this release will come in two versions: one narrated by Star Trek: The Next Generation’s Wil Wheaton, and the other by Buffy the Vampire Slayer’s Amber Benson, who are each popular audiobook narrators.

In Lock In and an accompanying novella Unlocked: An Oral History of Haden’s Syndrome, Scalzi depicts a world facing a unique medical crisis: a global flu pandemic that killed millions of people and left a small subset of the survivors suffering a condition known as Haden’s Syndrome, which left them fully aware, but paralyzed — or “locked in” to their bodies. In the aftermath of the event, the United States initiated a moon shot-style program to help the so-called Hadens interact with their surroundings and developed a system by which they could pilot robotic bodies called Threeps, nicknamed after Star Wars’ C-3PO. Some Hadens also purchase the services of people called Integrators, who can allow Hadens to take over and pilot their bodies. Lock In follows a character named Chris Shane, a new FBI agent tasked with solving a murder committed by an Integrator — or more likely, an unknown Haden controlling him.

When Scalzi wrote Lock In, he made a creative decision to not reveal Chris’ gender, creating a character who readers could read as male, female, or neither. He explained that he did it as a writing challenge, and realized that in this world, gender might not be easily distinguishable for a Haden using a robotic body. Chris grows up with Haden’s Syndrome, which means interacting with the outside world through a series of readily swappable machines, which can be presented in any number of ways to the general public.

In Scalzi’s upcoming novel, Head On, Chris is back with a new case, this time investigating the death of a Haden playing a particularly violent sport known as Hilketa, in which players try to rip the head off a robotic member of an opposing team. Audible released a pair of audiobooks for Lock In, and with Head On about to hit stores, it’s bringing Wheaton and Benson back to narrate another pair of editions, highlighting the fact that Chris could be male, female, or non-binary.

Benson told The Verge that this approach is particularly important in 2018. “Framing things within the lens of an ascribed gender, it comes with a whole set of rules,” she says. When she first voiced Chris in Lock In, she went into the story not knowing about Scalzi’s decision, but picked up on it, noting that she’d previously read a mystery series with a gender-neutral protagonist. “I found that talking to people about it, they don’t realize, and I think most people make an assumption.”

“I think we are living in a time when gender is becoming more and more fluid,” she says. “There are more non-binary ways of looking at gender. I personally feel that the idea of what it means to be male, female, some sort of mix, or non-binary is created by the society we live in.” She says traditional definitions and assumptions have begun to change. “These kinds of stories are ways to change that conversation, to make it a better place for people to be who they are,” Benson says.

Wheaton concurred and noted that it’s extremely rare for two narrators to work on the same story. He told The Verge that he didn’t think of the novel’s character as having a gender, and that while people will likely assign one to Chris based on which version of the audiobook they’re listening to, he doesn’t think that it’s especially important to the story.

By its nature, audio narration adds an additional layer of information and context for the listener, and releasing gendered versions of the book changes how listeners will approach it. “When my voice is attached to the character,” Wheaton says, “I think the listener probably feels like it’s male, while when Amber reads it, they probably feel that the character is female. But because John [Scalzi] specifically never gendered the character, I chose not to gender Chris.” Benson explained that the two versions help challenge the inherent assumptions that readers bring to the character. “We have a set of parameters that we put characters in based on their gender. And when you read it, I hear the character in my head, so I can imagine it’s disconcerting when you listen to an audiobook and it changes the gender on you.”

More authors have been overtly considering the role gender plays in science fiction. Ursula K. Le Guin notably explored genders beyond the typical binary male and female presentations in 1969’s The Left Hand of Darkness. More recently in the Imperial Radch series, Ann Leckie depicts a society where she / her are the default pronouns. Other authors, like Mike Brooks in his Keiko trilogy and R.E. Stearns in her space opera Barbary Station, similarly depict non-binary characters. Mainstream audiences are becoming more aware of gender depictions in popular culture, as shows like Amazon’s Transparent have pushed the issue, while highly visible figures and policy decisions have stirred up debate across the country. Novels like Head On inform the discussion by questioning the depictions of individual characters and making readers aware of their own internal bias.

Wheaton says he doesn’t see Head On as a work that particularly ties in with America’s larger considerations of gender, but says, “We’re at a moment where we as a society are willing to look at gender as a construct, [and] I think it is wonderful that in that context, with this story, we are not experiencing this narrative character through the prism of gender at all. We’re experiencing them through their intellect, personality, and relationships.”