Inspired by a Scandinavian fairy tale, “East of the Sun and West of the Moon,” Edith Pattou’s YA novel East introduced adventure-seeking Rose, who embarks on a dangerous quest after accepting a white bear’s mysterious offer to live with him in a distant castle in exchange for securing her ailing family’s health and prosperity. The 2003 romantic fantasy received multiple honors, including selection as an ALA Notable Book, and 15 years after its publication, Pattou has written a sequel. This month, HMH is releasing West, in which Rose sets off on another perilous journey, this time to find her missing love, Charles (whom a curse had trapped in the bear’s body), and her new mission involves the highest of stakes: the fate of the entire world is at risk. Pattou spoke with PW about what moved her to write both sagas, and what might—just maybe—lie ahead for her intrepid protagonists.

How and when did you come upon this classic Scandinavian tale—and why did it inspire you to write East?

Growing up outside of Chicago, I was a big reader, and I remember finding at the library The Blue Fairy Book by Andrew Lang, a collection of stories from many different cultures. I fell in love with “East of the Sun and West of the Moon,” a Norwegian story about a heroine who had no name—but who was everything I wished I was. She was so brave, resilient, and honorable—she had a moral compass to her. She sets out on a journey with a white bear—one of the fiercest predators in the animal kingdom—to save her family. I remember vividly loving the idea of this girl riding on the backs of the winds to get to different lands—she was a true inspiration.

The years passed, and when I was in grad school studying to become a librarian, the first novel I read that was based on a fairy tale was Beauty by Robin McKinley, which gave me some insight into how you can make a layered novel from a relatively short fairy tale. At the time, there were no novels I could find based on “East of the Sun and West of the Moon,” and I decided I wanted to try to write one—and to put my own spin on the tale. I’m not sure why, but I decided to set the novel in 1500s Norway and I wanted to build a world to inform readers about what life was like then. I did a lot of research—in fact I still have folders filled with information about weaving, compasses, map-making, the Arctic—and of course white bears.

An obvious question, given the time lapse between the pub dates of East and West: what inspired the sequel after so many years?

I’d always thought of East as a stand-alone book, and never thought I would write a sequel. I continued to get so many letters from readers asking for more about Rose and her white bear, and I’d think to myself, “I already gave these two their happy-ever-after—I even gave them four children for heaven’s sake!” And then about two years ago, I had a “gotcha” moment that arrived as a “What if… ?” I can’t say specifically what it was—that would be a spoiler—and it took me a while to figure out the story, and who or what might not want Rose and Charles to live happily together. I also needed to discover how to make Rose—I probably shouldn’t say this!—the same kickass character. So I began to weave a new journey for her—with even higher stakes. She’s a mom, but she’s still a very strong action heroine. She is an adventurer—that’s in her soul!

Was it tough to reconnect with Rose and Charles as you continued their story, or were their voices easy to resurrect?

It was not difficult to reconnect at all—it was a total pleasure! Rose and Charles are both so dear to my heart. I always felt a little sorry that I hadn’t given Rose’s mother a voice, so I shifted some of the perspective from her father to her mother. It was wonderful to revisit these characters, especially since I’ve learned from letters I’ve received from young women over the years—letters both heartfelt and heartbreaking—that Rose represents a beacon of hope for them. She lets them know that if you can hang in there, despite obstacles life throws at you, you just might get your own happy-ever-after. That’s what the girl in “East of the Sun and West of the Moon” represented to me so many years ago.

Do you feel as though you leave Rose and Charles in a good place at the conclusion of West—and might there be more of their story to tell?

I’m very happy with where these characters are. I think the ending of West has a bit of an echo of the ending of East. I feel that Rose and Charles grow so much in West—they barely knew each other in the first book, but in the second they get to know themselves and each other so well. They’ve gone through a lot together. And they’re survivors.

In terms of the future, readers have asked me, “Can there can be a North or a South?” I’ve learned from my mistakes not to rule anything out—and I do have some ideas, but to take away Rose and Charles’s happy ending yet again seems a bit sadistic! I might have to play with the idea of going into the next generation and focusing on their children. They just may have an adventure ahead!

West by Edith Pattou. Houghton Mifflin Harcourt, $17.99 Oct. ISBN 978-1-328-77393-7