LOS ANGELES (Reuters) - "Twilight" author Stephenie Meyer brings her romantic futuristic thriller "The Host" to movie fans on Friday, trading the vampires and werewolves for aliens who invade planet Earth, taking over human bodies.

The film stars, Saoirse Ronan as Melanie Stryder, whose body is taken over by an alien soul called Wanda. Eventually the two-in-one female team work to save the human race from total annihilation.

Meyer, 39, who was raised Mormon and attends church regularly, talked with Reuters about "The Host," working as a producer on the project and how her life has changed since the first "Twilight" film came out in 2008.

Q: How did Saoirse Ronan play Melanie and Wanda in the same body?

A: They have conversations throughout the entire film, but (she plays) two different characters that have different chemistry with two different guys. She's one person, but emoting a separate person when she's with Jared and another when she's with Ian.

Q: How did things evolve for you that you are now producing your adaptations? It didn't start that way on "Twilight."

A: It's not normal for an author to be very involved. On "Twilight," I think they were nervous about me, but I totally behaved. I came on set, I was excited, so they didn't mind having me around. With each movie I was able to be more involved.

I worked really closely with ("The Twilight Saga: New Moon" Director) Chris Weitz, especially with the casting of the side characters. We saw eye to eye really well.

Q: Did the success of "Twilight" give you producing clout?

A: After "Twilight" did really well, I think my opinion had more weight. With "The Host," from the very beginning (producer) Nick Wechsler came to me and said, 'Let's do this together.' And he meant it. I was going over the (script) notes with Andrew and the actors would come to me and say, 'What do you think?' It was a nice group. All our opinions were valued by each of us.

Q: You live in Arizona, just north of Phoenix. Do you ever think you should move to Los Angeles and work full-time in Hollywood?

A: I would never come and live here. No offense to the people that do, but I can't imagine raising kids in this town. There are a lot of plastics, even kids getting plastic surgery. And the materialism - that overwhelming sense of what you look like being the most important thing, I think that would be really difficult to live with every day. It's hard enough to be here for a week at a time. Every day you start feeling less-than because everyone's so beautiful and polished.

Q: Your three sons range from ages 10 to 15. Do they think you're the coolest mom ever because you created "Twilight?"

A: I think it's a detriment for them. It's embarrassing to have your mom be that "Twilight" lady. They would all love it if nobody knew my name. (With my oldest), people tease him a little bit. I know a lot of girls talk to him who might not otherwise. My middle son (Seth), he has a fake name. For a while it was Bernard. 'He'd be like, Hi I'm Bernard.' He doesn't like the reaction when people say, 'Oh you're that kid.'

Q: How has life changed for you since your film success?

A: People let me make movies, which is kind of cool. That certainly wasn't something anyone was going to let me do before. I've grown a lot in my confidence and in my ability to do interviews. I don't freak out as much about all these people taking pictures. I do have to be away from my kids more than I'd like, but they're so cool and mellow about it.

Q: Have you been able to fulfill any personal wishes since "Twilight" brought you to the pop culture forefront?

A: I'll tell you a story that's in the first "Twilight" book, where a little piece of me sank through to the novel. When Bella sees Edward's piano for the first time, she (vows) if she ever had a windfall, she would want to get her mom a piano like that. Well I was able to get my mom a piano like that. It was really exciting to get to do that.