Who hasn’t fantasized about becoming a character in their favorite book? Author James Riley has turned that idea into a bit of wish fulfillment by creating the briskly selling Story Thieves series (S&S/Aladdin), whose first two books have sold more than 170,000 copies combined since the publication of book #1, Story Thieves, in January 2015. The paperback edition of Story Thieves has been on the New York Times bestseller list for 20 straight weeks to date.

In the first volume, regular kid Owen sees his classmate Bethany climb out of a book in the library. He soon learns that she’s a half-fictional girl (her mother human, her father fictional) in search of her missing dad, and insists on joining her quest, by traveling into one of his favorite fantasy series to procure some help. By book #2, The Stolen Chapters (Jan. 2016), Owen needs to team up with boy magician Kiel (the hero of his beloved series), solve a real-world mystery, and rescue Bethany from disaster. But at that book’s end, the author leaps into the action, too, adding a whole new level of complexity.

“I used to get so drawn in to stories like the Chronicles of Prydain [by Lloyd Alexander] and other fantasy stories,” Riley said of what sparked his Story Thieves idea. “I wanted to write about characters who were jumping into stories and wondered how much I could do on a meta level. How could I write the characters while self-examining the book? There were lots of fun things for me to play with. I started out in the vein of The Phantom Tollbooth, but then moved away from that and kind of insinuated that I was the villain of the story – named “Nobody” – as well as the author. I wanted the book’s characters to meet their author, because the author is their worst enemy. I wanted to be sure and let them have some sort of confrontation.”

That confrontation is the setup for book #3, Secret Origins, due out in January, and according to Riley, is a “superhero story.” He explained his master outline for the scope of the series: “I planned it out as five books from the beginning,” he said. “I wanted each one to be a different type of book.” So far, he’s delivered a fantasy-adventure tale in book #1 and a mystery for book #2. “I’ve just finished book #3, which is a superhero story,” said Riley. “Book #4 is a play on a choose-your-own-adventure style of book, and the fifth book wraps it all up. So far, I’ve followed out my plan.”

But Riley is excited about a small tweak in the plan for book #3, inspired by his fans. “The kids really go off in their own direction, asking if they could jump into this or that story,” he said of the questions readers pose during his appearances. “They really seem to get into it. In fact, I’ve been playing with the idea of crossing over into another author’s series,” he added. “Brandon Mull is working on a new sequel to his Fablehaven series [Dragonwatch, spring 2017]. He and I were touring together [in 2015] and we came up with an idea for my characters Owen and Bethany to jump into one of his Fablehaven books. There is a spot that works without disrupting his book. It’s a bonus story that will be in my third book. It will tie in with the stolen chapters I write about in my second book, and it will help introduce what is coming up in Bandon’s new series.”

And the series-jumping departure is not the only change ahead for the series. “They’ve ramped up the frequency of the books,” said Riley, meaning that book #4 is scheduled to be published six months after book #3. “This is the first time I will have written a book in six months!” he said, noting that he still maintains his day job as an editor at USA Today as well.

Riley’s success so far is the result of a steady climb that began with his debut, the fractured-fairytale-flavored Half Upon a Time trilogy. And, according to his editor, Liesa Abrams, v-p and editorial director of Simon Pulse and associate editorial director of Aladdin, Riley is right on track. “He provides a shining example that the traditional publishing model can still work in today’s world of ‘overnight blockbusters,’” she explained. “Every year, James has sold more books than the previous year, and it was his fourth book – in paperback! – [Story Thieves, the first volume in the series] that landed on the bestseller list.”

Riley had hoped, of course, that the scenario would play out this way, but wasn’t sure. “My first book came out in 2010 and my editor told me that if I came in at a moderate advance I could grow, and slowly build an audience with each book,” he recalled. “It’s hard to see all that at the beginning, but it’s actually happening. One of the great things about success is proving her right, and also seeing kids who know my books. Oh, and getting into the Scholastic Book Club catalog! That was huge for me for lots of reasons, but mostly because I remembered how much I loved that catalog when I was a kid. It’s been so fun.”

Abrams said she knew she wanted to work with Riley because of the qualities she saw in his writing. “When I acquired Half Upon a Time, back in 2009, his humor captured me instantly,” she said. “Nothing works in middle grade like humor does! Pair that with his innate sense for great adventure storytelling, and I knew we had something special.” In Abrams’s view, Riley’s own passion for books expresses itself in the ways that both of his series feature characters merging from the real world with a fictional one. “With these blurred lines and a meta approach,” she added, “readers can see themselves so easily in these stories. He strikes the perfect balance between playful jokes that gently mock familiar tropes and clear respect for why those archetypes work.”

Marketing and publicity for the books has grown along the way, too. This past January Riley went on a seven-city tour, including an appearance at the ABA Winter Institute. Story Thieves was one of the prizes of the Boys’ Life annual “Say Yes to Reading” contest (sponsored by S&S) in the magazine’s summer reading program, and was the featured title of a Reading Arcade Takeover on funbrain.com. Riley is comfortable engaging with his fans online, too. As one example, he makes time whenever possible to respond to email questions on his website. Not long ago, he said, he received a letter from a mother about her son who has dyslexia. “When she read him the Half Upon a Time, he told her he wanted to read the other books on his own,” Riley recounted. “I don’t know how to handle that. It seems impossible that a kid would want to read something of mine so much that he would overcome a difficulty just to find out how the story goes. To get that kind of response warms my heart.”

But paramount for now is Riley’s work on the next Story Thieves title, the pick-the-plot volume scheduled for summer 2017. And that’s fine by him. “It’s always been my dream to be a fulltime writer,” he said. “My mom used to let us stay up late if we were reading, but not if we were doing anything else, so we learned early on that it was a good thing to do. I loved it. And now I love that something I do could be a springboard for kids’ imaginations.”