Stephenie Meyer says her best story ideas come to her when she’s alone. The author and movie producer came up with Twilight—the young-adult vampire-fantasy series she is best known for—after a dream she had in 2003. Three years later, the idea for her novel The Host was born while she was on a solitary road trip in the United States.

“I was really bored, and I tell myself stories to keep my mind busy,” Meyer told the Georgia Straight during a recent interview at Vancouver’s Sutton Place Hotel. “I somehow ended up in the middle of the idea of having two people in one body, both in love with the same person—because I love a really good complicated relationship.”

The Host, published in 2008, tells the story of Melanie Stryder, one of the remaining “free humans” alive after Earth has been invaded by an alien race called Soul. After sustaining a serious injury, Melanie wakes up to find that a Soul named Wanderer has entered her body, with access to all of her memories, including ones of a former lover named Jared. Together, Melanie and Wanderer struggle to find Jared.

“I initially assumed that this movie was unfilmable; I didn’t think you could do it,” Meyer said, describing her reaction to turning The Host into a movie. There were details in the story that she knew would be difficult to re-create visually.

“There are a lot of things you just can’t do on film, which in writing you never have,” Meyer said. “If I want a person to fly, they’re going to fly. In a movie, well, we don’t have the budget for them to fly, so they’re going to walk instead. There’s always that kind of compromise that you have to make that you don’t make when you’re writing.”

After reading the screenplay by Andrew Niccol, who previously penned The Truman Show, and talking to coproducer Nick Wechsler, who helped bring Cormac McCarthy’s novel The Road to theatres, Meyer signed on to help produce The Host (which opens in Vancouver on Friday [March 29] ). Casting the movie was a challenging experience for Meyer, who said that her vision of Melanie was very different than the appearance of 18-year-old Irish actor Saoirse Ronan, who won the lead role.

“I actually imagined Melanie to be half-Hispanic, so she was a lot darker in tone, and older for [her] age,” Meyer said. “She’s 20 at the beginning of the novel, but I always imagined her as, like, 25 because she had to have such maturity and such growth.”

However, seeing Ronan’s performance in 2011’s action thriller Hanna changed Meyer’s mind, and she said she’s excited for audiences to watch Ronan take on the role of Melanie.

“Her range is really unending, and I don’t think she’s had something she can’t do,” Meyer said. “She is one of a kind.”

Although writing remains Meyer’s first passion, she looks forward to gaining experience as a movie producer through her company Fickle Fish Films.

“With each movie that I’ve worked on, I’ve kind of gotten more involved,” she said. “It’s always something that’s very 3-D—your involvement—it’s very real. There’s always real people involved, and they’re bringing things that you couldn’t have even imagined.”