The star's new film is a homey affair, written by his girlfriend and co-star Zoe Kazan and directed by his "Little Miss Sunshine" collaborators.

“The more personal it is the more fun I seem to have,” says Paul Dano.   

He’s phoning from Chicago, discussing his twin roles as producer and star of the offbeat romantic comedy “Ruby Sparks,” and it’s about as personal a project as you can imagine.  The film was written by and co-stars Dano’s girlfriend, Zoe Kazan and it’s directed by the spouses Valerie Faris and Jonathan Dayton, in whose 2006 hit “Little Miss Sunshine” Dano had his first popular success.

Since then, Dano has been widely acclaimed for his electric performances as a set of twins in “There Will Be Blood” and appeared in such disparate films as the action blockbuster “Knight and Day,” the sci-fi western “Cowboys & Aliens,” the shot-in-Oregon pioneer tale “Meek’s Cutoff” and, earlier this year, the father-son drama “Being Flynn.”  He’s shown intelligence and daring in his roles as well as droll comedy and a strange, gangly physicality.  He’s 28 and has been in movies for more than a decade, but he feels like a still-emerging talent.

In “Ruby,” which opens in Portland on Friday August 3, Dano plays Calvin Weir-Fields, a novelist who had massive critical and commercial success a decade ago with his first book and has been unable to follow it up.  Hobbled by writer’s block, he follows the advice of his therapist and starts to write about a girl who could accept him flaws and all.  The experiment is so successful that he not only writes dozens of pages but the girl herself -- the Ruby of the title -- shows up in his house in the flesh.  He has, in effect, created his own real-life sweetheart out of his head.

The skinny, skittish Calvin, with his fastidious manners and nerdy spectacles marks, another absorbing turn for Dano.  As the actor explains, although Calvin has the trappings of success, what appeals about him as a character is the way that he’s broken and needy despite his superficial good fortune.

“As an artist I was immediately empathetic toward the idea of people asking something of you and wanting you to be something,” he says.  “I don’t think being labeled as a genius at 17 or 18 is a great thing, so there’s some sort of arrested development there, potentially.  And I think of the other things about him:  He’s lonely.  He’s got love from his brother, but that’s about his only friend.  His father has passed away, and he has a significant ex-girlfriend and he has this dog to try to help him meet people.  But that’s not really working.  I think those are all emotional things, and I guess I felt empathy or sympathy for him immediately.”

Dano was aware from the start of Kazan’s screenwriting process that he was intended to play the role, but he says that he kept as much distance from her creative work as he could.  

As he remembers, “About three to five pages into reading it for the first time, I said, ‘Are you writing this for us?’ And she said ‘Yeah.’ She would show me pages and I’d try to a) be a good boyfriend and b) be a good bounce-board and ask good questions.  But I didn’t want to have a say in it, because I like to be surprised, and I want to be challenged, and it was better to engage her in talk about the whole thing and not just about Calvin.”

Other than acting the lead, he also took on some of the responsibilities of a producer, in part, he explains, to protect Kazan’s vision of the story.  “We knew that we wanted to be in it,” he says, “but we also knew that we wanted to see it get made in the right way.  So it was important to us to be involved to a certain degree, and mostly that meant sending it off to the right people to start with. Jonathan and Valerie were our dream directors and out first choice.  And from that point on it was a collaboration: getting involved in more aspects of the filmmaking process than I normally do as an actor -- casting and little parts of pre-production.”

It’s only coincidental, according to Dano, that he appears as a writer in two films this year:  “Ruby” and “Flynn.”  In fact, he continues, the characters he plays in the films are, in his mind, completely distinct.  “The Nick Flynn character, I don’t think of as being bookish,” he says.  “I think he discovered himself being a writer.  The defining quality of him for me was being an addict and having issues with his father.  Calvin is defined by being a writer and by being a writer who’s had success and is having writer’s block.”

And, of course, Flynn’s is more or less a real-life story while Calvin’s tale is purely fantastical -- even though it has emotional reality to ground it.  “Flynn” can feel gritty and despairing; “Ruby” recalls the romantic whimsy of Woody Allen’s “Midnight in Paris.” “I think the beauty of (‘Ruby’) is that it walks a line tonally,” Dano says.  “It was important for us to have the highs -- the magic of romance and of fantasy.  But also to explore the full range of it, and hopefully there’s depth and even moments of darkness.  One of my favorite things about the film is that it has an element of the unexpected to it.  You don’t know where it’s gonna go with what it’s doing.”

Dano has many more films in the pipeline as an actor, but he admits that “Ruby” has definitely given him a taste for producing films.  “I’d like to be able to help get more films made that I’d want to appear in or want to see or that I think I have something to offer an audience,” he says.  “I’d like to be more proactive in that.”

But acting, he explains, will remain his chief pursuit.  “Once we were filming, it was all Calvin for me,” he explains, “and that’s how it would always have to be.  Setting up the film and helping find the right people was where my producing duties fell, and then, when you’re working with people you trust, you don’t have to worry about small things.  Finding people you share a point of view with is what’s important.  On this film, I was working with people who I had a rapport with and a friendship with and trusted 1000%, but at the same time we were doing something new together, and we had an intimate collaboration.”