Brian Truitt

USA TODAY

For a guy who has issues matching his socks, even Pierce Brown is a little amazed at how popular his color-coordinated sci-fi series has become.

His new novel Morning Star, the final book in his Red Rising trilogy, lands at No. 1 on USA TODAY's Best-Selling Books list this week, Brown's first ever appearance in the top spot. That’s just the first piece of good news, though. The second: Brown begins another three-part epic next year with Iron Gold, which expands on the cosmic saga of a multi-class struggle on Mars, he tells USA TODAY exclusively.

“It’s been fun to have it take on a life of its own,” Brown, 28, says of the Red Rising series, which centers on a lowly Red miner named Darrow who is transformed into a mighty Gold, the powerful ruling elite, to take down the oppressive Society from within. “I feel like I’m not even creating as much as I’m revealing things, and that’s a really lovely thing for me to have because it’s so fun to get to explore my own world.”

The first series, begun in 2014’s Red Rising (which peaked on USA TODAY's list at No. 82) and continued in 2015’s Golden Son (which landed at No. 14), was always meant to focus heavily on Darrow's quest. (A Red Rising movie is in development at Universal Pictures.)

The world of the books is comprised of a class system defined by a spectrum of colors, from the working-class Reds, servant Browns and militaristic Grays to priestly Whites, bureaucratic Coppers and the upper-crust Golds.

The new trilogy takes place after the end of Morning Star (Del Rey) and will center on the consequences of the hero’s actions as well as on those folks now living and growing up in a landscape that’s had its ruling order shattered.

“That is what the series will explore: Have they unleashed dark ages or a renaissance?” Brown says. “I think you can pretty much bet it’ll be dark ages for a little while.”

In addition to imagining what human colonies on other planets are doing while the Martian drama is going on, Brown wants to dig into “the cracks of civilization” and explore elements he’s only been able to touch on briefly, such as the Mafia-like Syndicate. Plus, the cast of the Iron Gold series will introduce new characters and bring back fan favorites such as Darrow’s loyal friend Sevro and the Gold girl Mustang.

Brown also sees the new trilogy making this universe more real to his readers, from the young-adult crowds to older fans of sprawling sci-fi epics, allowing more depth and storytelling the way Dune, Star Wars and The Lord of the Rings did for him growing up.

“Anyone who writes books is at least mostly an introvert,” Brown says. “It’s amazing to be able to share that internalized part of myself, that little world that no one really knows about. I just wrote down it down on a piece of paper just to be crazy, and people loving that is so strange.”