Fans of the Stephenie Meyer novel The Host can rejoice: there could be lots more to come.

Meyer — who turned the vampire love story Twilight into a multi-billion-dollar movie franchise — is working on a sequel to The Host, a futuristic love story about a world that is occupied by aliens who take over the minds of humans. The book, which was No. 1 on The New York Times’ bestseller list for 26 weeks, has become a film starring Saoirse Ronan as Melanie Stryder, one of the last surviving humans, and Max Irons as Jared, her love interest.

After the second book, there could be more as well.

“I hope so,” Meyer said Monday from Vancouver, one of the cities on her North American tour to promote the film. “I’m working on a sequel now. I don’t know about a third one. I have the outlines and everything.”

But that doesn’t mean it’s coming for sure. It depends on where the characters take her.

“A lot of time a book surprises me in the writing, where they go in a direction you’re not planning,” Meyer said. “It’s always tricky to anticipate one further along than the one you’re on.”

She said a similar thing happened with the Twilight story, which was written as one book and turned into a trilogy.

“The character that took me by surprise in that one was Jacob Black, who wasn’t supposed to be a major character and then ended up influencing so much of where the novels went,” Meyer said. In The Host, the surprising character was Ian, a rival for Melanie’s affections, “who was not supposed to be as involved and then become one of the main leads.”

She added, “Which is always the most fun when you’re writing: when the characters sort of take over and seem to do it on their own, it’s a real cool experience.

The Host opens March 29.