Question: What is the job of a novelist on the set of the movie adaptation of his book? When John Green arrived to watch The Fault in Our Stars being shot in Pittsburgh on a cold morning last September, it was a bit like Aslan making an appearance in Narnia: here comes the benevolent deity, padding amiably through his creation. Everybody wanted to say hi. Shailene Woodley–who plays the hero, Hazel–said hi. The director, Josh Boone, said hi. The guy holding the boom mike said hi. “I don’t know what authors are supposed to do on movie sets,” Green admitted, and it wasn’t clear that anybody else knew either. But everybody was happy to see him anyway.
That’s the thing about John Green, or one of the things anyway: people are generally glad to see him. Green is the author (or co-author) of five best-selling young-adult novels, of which The Fault in Our Stars is the most recent and the most best-selling (though they’re all pretty popular). But he’s also what is commonly and increasingly less oxymoronically called an Internet celebrity, presiding over a sprawling social-media empire that runs largely on his immense personal charm. With his brother Hank he heads a YouTube channel with 2 million subscribers and an organization called Nerdfighters that advances social causes and generally celebrates nerdiness. He has 2.4 million followers on Twitter. In an inversion of the natural order of things, Green is more famous than a lot of the actors in the movie.
Just as Green is a different kind of author, The Fault in Our Stars is a different kind of story from Twilight and The Hunger Games and the other major young-adult franchises of the past decade. Most obviously it’s a work of realism, inspired by five months Green spent working as a chaplain in a children’s hospital, as well as by his friendship with a teenage cancer patient named Esther Earl, who died in 2010. The book’s heroes, Hazel and Augustus, are two clever and charming teenagers who live in Indianapolis. They both have cancer. Hers is in her thyroid and her lungs–she wheels around an oxygen canister to help her breathe–and he lost a leg to it. Hazel and Augustus meet in a cancer support group. They fall in love.
Without the cancer The Fault in Our Stars would just be an intensely wise and charming book about teenage romance. But the fact that the main characters are terminally ill makes it something more. Watching Hazel and Augustus summon up the courage to love each other, even in the face of constant pain and an almost certain early death, is a deeply, powerfully moving experience. The Fault in Our Stars is a great romantic comedy, but it has the long, dark shadow of a great tragedy.
Still, it wasn’t supposed to be a movie, for the simple reason that Green didn’t want it to be one. “I did not want to sell the movie rights for The Fault in Our Stars,” Green says. “It was a very personal story for me. Also I’d had some unhappy experiences before, and I didn’t want a movie I didn’t like being made from a book that’s so important to me. This book frankly is more important to me than my other books.” (He laughs. But he doesn’t take it back.)
It’s important to a lot of other people too. The Fault in Our Stars has 10.7 million copies in print, and after 77 weeks it’s still No. 1 on the New York Times young-adult best-seller list. Naturally Hollywood called–but Green said no. “Everyone was like, ‘Oh, it’s a Love Story for a new generation!’ And I was like, ‘That was the worst thing you could’ve possibly said to me.'” That’s where things stood until he heard from two producers, Wyck Godfrey and Isaac Klausner, whom he knew already from an earlier project. When they described the movie they wanted to make, it was the same one that was in Green’s head. “I wanted it to be a funny movie and a sweet movie,” he says, “but I also wanted it to be a movie about asking the question, What constitutes a good life? And whether it’s possible to have a good and meaningful life even if you have a short life.”
The movie was greenlighted with a budget of $12 million, which now seems like a steal for a movie that is shaping up to be one of the summer’s blockbusters. But at the time it seemed like a risky proposition. It was a lot of money to be spending on a movie about dying children. “The idea of having a female lead in a movie wear a nasal cannula for every moment in the movie,” Green says, “that’s a very difficult thing to convince a studio to do.”
Green was involved with preproduction–he watched the auditions and made notes on the script–but he didn’t plan on spending a lot of time watching the movie actually get made. Then a funny thing happened: he couldn’t stay away. “I was going to come just for the first few days, just to get a feel for the set and say hi to all the actors and whatever. But immediately they were like, ‘Just come back and stay the whole time!’ And I was like, ‘All right!'” So for most of the shoot, he flew to Pittsburgh on Sunday nights and then back to his home in Indianapolis for weekends. “It’s like having a great audience right there,” Boone says. “He’s so pure. He’s not movie-obsessed. Like his favorite movie is Die Hard 4. I don’t think he was joking when he told me that.”
On this particular day they were shooting a scene set in the home of a fictional writer named Peter Van Houten, who is Hazel’s favorite author but who turns out to be kind of a jerk. When Boone called action, Woodley, who is in reality a healthy and relatively extroverted 22-year-old, somehow sank into herself and became thin and pale and quiet and 16. (It helped that Ansel Elgort, who plays Augustus, is 6 ft. 4 in. She looked tiny next to him.) The scene called for Hazel to tell Van Houten, played by Willem Dafoe in soiled pajamas, “Go f-ck yourself!” She delivered the line 10 times in 10 different ways. Then they did an extra take where she told him to go to hell, in case they needed a version for TV.
For Green part of the appeal of being on set is the company. Writing novels is a solitary pursuit: if there’s a collaborative element to it, it’s between writer and reader, two people who generally never meet. “You never get to see that collaboration happen,” Green says. “It all happens alone in their room and you’re not there. And if you were there it would be superweird, like watching someone sleep or something. Here I feel that collaboration you have with readers, except I get to witness it and be part of it.”
Though witnessing it can be a little uncanny. “It’s like I’m hallucinating something I imagined six years ago,” Green says. “So it’s like an extremely delayed hallucination.” One crucial scene in the book takes place at the Anne Frank House in Amsterdam, and even if you’re not the author, it’s a bit surreal to walk into a darkened warehouse in Pittsburgh and find a meticulous, full-scale reproduction of Anne Frank’s home inside it. Witnessing it can also be upsetting: making The Fault in Our Stars brought back some of the raw emotions that inspired the book in the first place. “I think the first thing that I saw was Hazel’s house,” Green says. “When they opened the door–I f-cking cried. I was thinking a lot about Esther, because Shai with her puffy cheeks looks a little like Esther with the cannula–it’s very difficult to describe.”
In fact, if there’s one thing everybody agreed on about Green’s role on set, it’s that it involved a lot of crying. “He’s encouraging,” says Boone. “Mostly he’s crying behind the monitors. Like I showed him the first cut of the throwing-eggs scene at Monica’s car and he laughed uproariously the whole time and then cried at the end. And then he asked to see it two more times.” Green confirms this, up to a point. “Here they think I’m such an emotional person,” he says. “I really don’t cry that often. But I do cry every day when I’m on the set. They make fun of me. Nat Wolff”–who plays Isaac, Augustus’ best friend–“said, ‘John Green cries at a good meal.’ And that’s not true! That’s not a fair assessment at all.”
The actors studied him for whatever bits of himself he put in his characters, which they could then take and use in their own performances. “Until I met John I didn’t really understand the tone and the voice of Augustus,” Elgort says. “This superconcise, supersmart way that’s so witty but not annoying. Once I heard John talk, it made sense to me.” Green also functioned as something like the movie’s conscience. After a take, people often glanced over at him to get his reaction, to confirm that what they were doing matched up with what was in his mind. “If you’re getting something wrong, he doesn’t say much,” Godfrey says, “but there’ll be a look on his face where you’re a little bit like, O.K., what’s up? And he’ll say it.”
Green, though, insists he hardly ever overruled anybody on set. The only example he can come up with is the time he tried to get Elgort to take off his Knicks cap, because–as is made quite explicit in the book–Augustus doesn’t like basketball. But it turned out Elgort wasn’t in costume. He just happened to be wearing a Knicks cap that day. It stayed on.
If Green had a job on set, it may just have been to radiate his particular brand of enthusiasm. It was to be John Green. “Everyone has their biggest fan on set when John is here,” Woodley says. “He is my biggest fan, he is Ansel’s biggest fan, he is Josh Boone’s biggest fan, he is the boom operator’s biggest fan.” In between takes, Green met Dafoe for the first time, and they rapidly established that Dafoe’s parents lived near the house in Florida where Green grew up, and one sensed that before long Green would be Dafoe’s biggest fan too.
As the world’s ultimate authority on the work of John Green, he’s in a position to say, You got it right. “The problem with movie sets is that everybody has an important job,” Green says, “and that job naturally comes with some stress. But I don’t have an important job at all here. And when they’re all like, ‘This take, that take, this take, that take,’ I’m like, ‘But you know what? They were all pretty good though.'”
This appears in the June 09, 2014 issue of TIME.