Ruby Sparks defies easy categorization. That’s not because it’s so original; it isn’t. Writer’s creation comes to life? Definitely seen it before. Its bigger stumbling block is that it can’t decide whether it’s a funny drama or a serious comedy.

And then there’s Paul Dano, who, as good an actor as he can be, isn’t quite right as Calvin Weir-Fields, a 29-year-old writer who produced a successful and much beloved novel at 19. A decade later, he hasn’t written a follow-up, though he has published some well-received short fiction.

When Dano’s playing the comedy of Ruby Sparks, he’s on target. When he’s playing the drama, he’s creepy and mildly demented, a contemporary version of There Will Be Blood’s Eli Sunday.

So what is Ruby Sparks about? Control. Nothing more. Nothing less. Calvin, struggling with writer’s block, tells his psychologist (a charming and amused Elliot Gould) about his problems and the shrink encourages Calvin to write one page, even if it’s bad.

Ruby (Zoe Kazan) has appeared in several of Calvin’s dreams and before long he’s heeding the shrink’s advice and typing away about her with joy on an old, standard typewriter. (The standard typewriter, usually a hipster tool, stands in as a creaky metaphor for Calvin’s uneasiness with new things.)

Some of Ruby’s clothing shows up in Calvin’s apartment. Then one morning she’s there, asking him what he wants for breakfast. When Calvin figures out he isn’t crazy, he begins having the best time of his life with the girl of his dreams.

Things go awry when Ruby wants to live her own life, including meeting Calvin’s friends and taking art classes. Calvin finally introduces Ruby to his brother, Harry (Chris Messina, who couldn’t look less like a Paul Dano relation), and, once Harry determines his brother is sane, warns him about trying to control your significant others while also encouraging him to test Ruby’s limits.

As Ruby, Kazan is delightful. She moves past the manic-pixie-dreamgirl intimations of the character (and as Kazan is the screenwriter, she should) and rounds Ruby out as much as she can be rounded out when she’s a living figment of her creator’s imagination. Kazan has some truly funny moments when Calvin adjusts Ruby’s personality to be more needy, and when he tries to write her as blissfully happy.

The last 15 minutes, when Ruby learns who she really is and Calvin’s worst controlling impulses come out, teeter between repellent and relieving, but not because that’s the correct tone. Dano looks queasily orgasmic as he makes Ruby, literally, dance for him. Then again, Calvin is essentially having sex with himself for an entire movie, so maybe the denouement isn’t such a leap.

Ruby Sparks wants to think it’s asking questions and letting its audience find answers, but don’t worry yourself. The movie isn’t that deep. It’s better treated as a pop confection. Enjoy it and try not to think that if you knew Calvin in real life, you’d find him a total twit.

Directed by Jonathan Dayton and Valerie Faris / With Paul Dano, Zoe Kazan and Annette Bening / UA DeVargas, R, 104 min.