Mills’s The Obsoletes (Skybound, May) is a coming-of-age story about Darryl and Kanga, two basketball-obsessed brothers who must hide the fact that they are robots.

You’ve worked on this book for 18 years. Was it always going to be about robots?

Robots were definitely not in the first draft. The original novella sat around for seven years. I got some feedback on that version, and I’d also been writing some robot stories when it just came to me: “They’re robots!” Then I rewrote the whole story. From that point forward Darryl and Kanga were more alive than they had ever been before.

How did you approach the themes of humanity and what it means to be human?

The fact that I had originally written these characters as regular humans made it easier for me to give them the qualities that make us human. Whenever I was writing about the more technical aspects of how they exist as robots, it was nice to default to the way a normal teenager or person would feel about it. There would be a different physiological explanation or outcome for what they were feeling, but their emotions wouldn’t be different. It was freeing to know that that was the strictest rule I had for myself.

You’re a middle school teacher. Does your work give you insight into the adolescent mind?

Definitely. Being around students lets me see their emotional reactions and the pace at which they think, process, and react to each other. That really does help when I’m trying to write a scene about that environment. The novel takes place in the early 1990s, when I was a teenager, and being a middle school teacher reminds me that adolescence is a really tough time where we don’t have it all figured out yet. But I’m heartened by kids and their willingness to accept people that are different from themselves, much more than when I was that age. It makes me hopeful about the future.

Why set the novel in the 1990s?

One reason I was drawn to this time period was using the Magic Johnson HIV announcement as an anchor in the novel. It was very inspiring for me to have one of my favorite basketball players and heroes go through something so hard, and I wanted to draw from all the uncertainty surrounding the announcement at the time. And then I just appreciated that the early 1990s was the last time that doesn’t really resemble this time in terms of technology. In a novel about a weird, advanced technology, I liked that the era didn’t include a lot of the modern technology that we rely on today.