Viggo Mortensen finds his most challenging role: a flawed father

Viggo Mortensen has certainly played his share of characters living on the edge.

Best known as the brooding Aragorn from the "Lord of the Rings" saga, the actor also has played a small-town diner operator hiding his gangster past from his family ("A History of Violence") and a man navigating a post-apocalyptic wasteland with his son ("The Road"). Yet the 57-year-old calls his latest role in "Captain Fantastic" - Ben Cash, a father living off the grid with six precocious children in the Pacific Northwest woods - "probably the most layered, complex and challenging" part he's ever had.

That doesn't mean that the gently comic drama, which won a directing prize at Cannes for writer-director Matt Ross, was as physically arduous as the naked knife fight Mortensen filmed for "Eastern Promises." The demands, in this case, were largely "emotional and intellectual," according to the actor, who lives in Madrid with his girlfriend, the Spanish actress Ariadna Gil, and who spoke by phone from the film's New York press tour event.

"It's subtle," he says about the irony of a character who is trying to prepare his children to navigate a world from which he has, despite the best intentions, largely shut them off. "There's nothing like doing your honest best - working really, really hard - and then coming to realize: No, you're on the wrong track. It's disheartening. But I like movies that make you feel that something you're doing is wrong."

After the death of the children's mother, Ben and his brood load up the family vehicle - a refurbished school bus nicknamed, for some reason, Steve - for a road trip to her funeral, and a journey of self-discovery when they clash with civilization.

A father himself (of 28-year-old actor Henry Mortensen, with his ex-wife, singer Exene Cervenka of the band X), Mortensen admits to sharing only a bit of Ben's eccentric parenting philosophy, which includes Navy SEAL-style survival skills, a tolerant embrace of a child who idolizes Pol Pot and regular Socratic discussions of literature and politics.

"The one way in which I am most like Ben," he says, "is that I am not a no-because-I-said-so dad."

Be that as it may, Mortensen dived into the role headfirst, scouting the shooting location in rural Washington state before filming had begun and volunteering to do advance planting of seasonal vegetables to establish a garden of the sort the family might have. He also visited a home he owns in Sandpoint, Idaho, six or seven hours away, loading up his pickup with personal possessions that could potentially be used as props.

Mortensen says he brought "sleeping bags, a canoe, bicycles, clothing, blankets, books, pots and pans - all things that I knew these people would have. It looked like 'The Beverly Hillbillies.' " Most of it made it into the film, including a loud patterned red shirt that the actor had squirreled away from his 1987 wedding.

Similarly, filmmaker Ross, who is raising a 13-year-old daughter and a 9-year-old son in Berkeley, California, describes Ben as something of a "fantasy version" of himself. Like Ben, the 46-year-old director (better known as an actor on "American Horror Story" and "Silicon Valley") celebrates "Noam Chomsky Day" on Dec. 7 (the far-left public intellectual's birthday). Ross also describes his own free-range childhood - "my mother was a rambler and a bit of 1980s hippie" - as including summers sleeping in a teepee not unlike the one that Ben and his family use.

"When I was growing up," Ross says, "some of our homes had electricity and plumbing, and some had neither. I can remember my brother and I just walking on the land for hours and hours and hours. In one house, we were eight miles from a cement road, 45 minutes from a general store, an hour from a town of 1,000. But I also went to public schools. I played football."

According to Ross, who spoke by phone from California, he never considered anyone other than Mortensen for the role of Ben, putting the production on hold for two years while waiting for the actor's schedule to open up. The idea for "Captain Fantastic," Ross says, arose not merely out of a question - how does one impart one's values to the next generation? - but also from a close examination of his own core parenting principles.

"I'm very conscious of trying to create compassionate, caring, tolerant global citizens who are empowered and benevolent," he says. "It's important to be physically fit and mentally well. Like Ben, I encourage my kids to be voracious readers and to challenge me - to challenge everything."

At the same time, Ross says, he lets his son play video games.

"I don't allow him to play first-person shooter games that are not appropriate for his age, where he's going around murdering people, but I think there are some games with some beautiful Japanese animation," he says

Mortensen says the film is much more than a modern-day "Mr. Mom."

"There is a real polarization in society," he says. "I felt it when I first read Matt's screenplay. And I felt it when we were shooting. In some ways, I feel this movie speaks to that theme, indirectly. Watching the movie now, in this year of 2016, with all of the polarizing rhetoric of the political campaign and the response to the shootings, the film echoes something that is real."

Like Ben, Mortensen says, too many people who mean well "have retreated into their camps, and they're not communicating."

Parenting is a lot like democracy, he adds, in which the tension between order and freedom is in constant flux.

"You have to know when to put your foot down and when to allow discourse," he says. "It's a balancing act. It's important to think before you shoot your mouth off, even if it's someone you may not agree with, or whose values you may disdain."

Mortensen says "Captain Fantastic" is not a message film, yet he manages to find one anyway - one that, like the film, sounds very much of its time: "Just because it's not possible to be a perfect dad or to be Captain Fantastic, that doesn't mean it's not worth trying."