He’s written a handful of blockbuster books, launched a pair of robust online communities, and cultivated an incredibly large T-shirt collection. Oh, and he hosts the mental_floss YouTube channel. Here’s how John Green made a generation believe in the power of awesome.

BY JESSICA GROSE | PHOTOGRAPHY BY JASON WALLIS

It's about 10 minutes into our conversation that John Green starts talking about the meaning of life. “I find it totally unconvincing to argue that everything happens for some discernible reason,” he says.

He’s describing the seven months he worked as a student chaplain at a children’s hospital, and the sentences spill fully formed from his mouth. “We have to grapple with the world as we find it, and we find a world that’s either random or else acts in a way that’s identical to how it would act if it were random.”

At 22, he watched 8-year-olds, who suffered every day of their short lives, die. It was difficult and sobering, but the experience also inspired The Fault in Our Stars, his latest novel. TFiOS (pronounced “Tiffayos” by fans) skyrocketed to the top of the young-adult charts without pandering to type: It’s a love story told by a heroine with stage four thyroid cancer. There are no vampires or mean girls in its pages.

But TFiOS is just the latest in a long line of Green’s achievements. He’s written four young-adult novels—three of which were simultaneously on the New York Times’ bestseller list. He’s cultivated a blockbuster YouTube channel with five different shows, all either hosted by him or his brother, Hank. He has millions of fans, or “nerdfighters,” as they’re lovingly called—who hang on his every word on Twitter and Tumblr and, of course, in print. And then there’s Brotherhood 2.0—the video experiment that began in 2007 when Green and Hank realized they were talking to each other only once or twice a year. To improve their relationship, they committed to communicating daily via YouTube, enforcing silly penalties when they missed a deadline. Six years in, they’ve not only grown a rabid fan base, they’ve charmingly discussed everything from religion to gay marriage to, well, songs about pants. Today, even celebrities are paying attention. Rapper Lupe Fiasco is addicted to Green’s YouTube history show and likens it to crack. Sherlock actor Benedict Cumberbatch has been caught in photos throwing the nerdfighter gang sign (two Vulcan hand signs placed across one’s chest). Yet Green’s appearance is hardly that of a celebrity. With slightly disheveled sandy hair, wire rim glasses, and a seemingly bottomless closet of polo shirts and tees, the quirky fast talker is like the enthusiastic Apple Genius Bar expert you have a secret crush on.

His guiding mantra—the one he constantly shares with readers—is “Don’t forget to be awesome.” The nerdfighters have not. As of this writing, through the microloan organization Kiva, more than 40,000 of his fans have given $3,148,825 to small-business owners in underfunded parts of the world. Green makes it a point to give back to his nerdfighters too. He personally signed every copy of the 150,000 first-print run of The Fault in Our Stars with a Sharpie, ensuring that anyone who couldn’t make it to one of his cross-country readings still had access to a signed book.

Of course, it isn’t just nerdfighters Green has touched. Though his most devoted cheerleaders tend to be teenagers, his books have reached millions of people of all ages. I first heard about The Fault in Our Stars from my 60-year-old mother-in-law. Time declared TFiOS the best fiction book of 2012. His fellow YA star author and sometime collaborator Maureen Johnson says she believes Green’s work is popular because “there’s something about him himself that’s coming through, and it’s not particularly sugarcoated.” It might not be shiny and happy all the time, but it is emotionally honest, and people respond to that.

It’s this hyper-contemporary combination of endless curiosity, Internet community engagement, and a do-gooder spirit that has made Green the pied piper of a certain kind of young nerd. Not only can he spin a great yarn, he’s pinpointed the next generation’s sweet spot, somewhere between self-reflection and the desire to do good.

Green comes by his sense of community involvement honestly. He grew up in Orlando, Fla., where his father was state director of the Nature Conservancy, and his mother was a community activist and organizer who worked in low-income neighborhoods. His interest in theology notwithstanding, he wasn’t raised in a religious household. Green, in fact, jokes that his brother has no patience for such “crap.”

Though they weren’t avid churchgoers, the Greens were encouraged to talk about big issues at the dinner table, where they were nightly reminded “what the meaning of life was and what your values should be.” Arguments with his parents were often about philosophy and ethics. “I’m sure it was infuriating for them to have this pseudo-intellectual kid who wasn’t very informed about this stuff that he was preaching about,” he says.

Green’s description of his teen self sounds like one of his characters. The heroes of his books are smart, funny, well-read outsiders, proud of their arcane knowledge. Miles “Pudge” Halter, the narrator of Green’s debut, Looking for Alaska, memorizes famous last words. Colin Singleton, from An Abundance of Katherines, is a math prodigy determined to derive a theorem that will predict the future of any relationship (he’s motivated by the fact that 19 consecutive girls named Katherine have dumped him).

The most fervent John Green fans—ahem, nerdfighters—are outsiders too. They love to read and write and don’t quite fit into the mainstream. The Nerdfighter Ning—a mini social network for diehard John and Hank Green lovers which Hank helped start—has nearly a hundred thousand members and provides a good illustration of the typical superfan. It has large subgroups for writer nerdfighters, nerd nerdfighters (apparently not a redundancy), gay-straight-alliance nerdfighters, and more than one theater geek nerdfighter coven. On Tumblr, a nerdfighter has put up a photograph of John and Hank rocking out like goofballs, overlaid with the text “John and Hank taught me not to care what other people think. Just be yourself. Your best nerdy self.”

What beams through Green’s work, aside from the humor, is his authenticity. In Looking for Alaska, teenage Pudge goes to boarding school in Birmingham, Ala., like Green did. At Indian Springs School, Green was in awe of his fellow students. He loved the atmosphere and the conversations; it’s a large part of why he writes for teens. “There’s this intense kind of almost joy,” Green said, of tackling philosophical issues for the first time. “Maybe we were talking about girls while we were talking about this stuff too, but it gave a certain intellectual charge.”

At Kenyon College, a liberal arts school in central Ohio, Green studied religion with a focus on early Islamic history. “I was interested in becoming an Episcopal priest,” Green remembers. “I don’t know that I thought it through very carefully.” Postcollege, however, he didn’t see many other career options. “It didn’t seem like anyone was hiring someone who had read a lot of Mark Twain. That didn’t seem like a job to me.”

He got into the University of Chicago Divinity School, but before enrolling, he began working at the children’s hospital. “It was difficult and traumatic,” he says. “I’ve never done anything harder than sitting with a parent as their child died. That happened every day.” When Green talks about his time as a chaplain, a slightly different self comes through. In conversation, he’s still like the online John Green, just dialed down a few notches. “He’s not always that shouty and spinning around in a chair,” Johnson says.

Green skipped divinity school and instead landed as a temp at the review journal Booklist, where he worked for the next six years, an experience that changed him. That seems to be a recurring theme in Green’s professional life. He follows his passions and through hard work, a bit of luck, and a boatload of natural talent manages to succeed beyond his wildest expectations. Around that time, he began writing about his experience at the children’s hospital.

Green describes this first attempt at a novel as “super embarrassing and humiliating” to read now. It was about teenagers fighting illness but “also about this alcoholic, 22-year-old, handsome hospital chaplain and which hot doctor he would hook up with next.”

But it was his mentor at Booklist, children’s author Ilene Cooper, who helped usher his first real book—Looking for Alaska—into publication. Though these days, when everyone and their mom seems to be writing a YA book to get onto the money train, Green says, “I sold my first book for $8,000. It wasn’t that much of a business opportunity.” He had another reason for writing for teens. “The world of adult publishing just seemed so packed and competitive and catty,” Green says. Besides, the books that were still the most important to him were the ones he’d read as a teen. As Green puts it, 16-year-olds see no problem with their two favorite books being a literary book like The Catcher in the Rye and a fantasy like Twilight.

In January 2007, following the publication of Looking for Alaska, the Greens launched Brotherhood 2.0. They were inspired by the work of Internet video pioneer Ze Frank, who uploaded a video every weekday, referred to his viewers as “sports racers,” and launched projects like having two people on opposite sides of the Earth place a slice of bread on the ground to create “an Earth sandwich.” “There was something so invigorating and special about those communities,” Green says.

Early on, the brothers had a few hundred dedicated fans. Friends thought they were crazy. Johnson says that when she first heard about the project, she thought, “That’s dumb—that’s superdumb. Why would you do that instead of writing?” Then, seven months later, Hank uploaded a song about Harry Potter, and the brothers’ YouTube channel exploded to 8000 viewers overnight. On the one-year anniversary of TFiOS’s release, John and Hank brought their Brotherhood to the stage at Carnegie Hall and sold out the place. Nerdfighters had united.

Let's go back to that stuff about being busy for a minute. Because these days Green also hosts videos for Crash Course, AP-level history and biology classes geared toward high school students and written by Green’s high school history teacher, Raoul Meyer, among others. John and Hank sell music, posters, T-shirts, and other merchandise through their DFTBA (Don’t Forget to Be Awesome) Records, and they organize VidCon, an annual conference for emerging YouTube stars that expects to draw 25,000 people this year. Meanwhile, he’s raising two young kids, both under 5 years old, with his wife, Sarah Urist Green, who curates and hosts a show for PBS Digital called The Art Assignment, in which he also appears. If you’re wondering if he ever wants to take a nap, the answer seems to be not really.

“It’s a privilege to have a platform to talk about things you care about, but it’s an irrevocable privilege. I try to take it seriously,” he says. And that includes admitting when he’s wrong. “Early on, I made a video where I made fun of Young Earth creationism. That seems like the safest joke in the world,” Green says, but “so many people were hurt because they felt like they were part of something [as a nerdfighter] that had been turned against them.” He still stands behind his pro-evolution beliefs but feels bad about being snarky. “It’s wrong to make people feel other and separate.”

That spirit of inclusion is at the big beating heart of what Green’s fans love about him. Mostly, they are bright teenagers who feel alienated from their peers. In Green, they’ve found a mentor—a kindred spirit who encourages them without pandering.

In a recent video, Green tells the nerdfighters about his experience on set at The Fault in Our Stars, and he connects it to a grander statement about humanity in his singular way. “I would argue that curiosity is not the most important human trait—the urge to collaborate is,” Green says. “Only we have the ability to cooperate, to make online communities and space telescopes and imaginariums and movies, so the great thrill of this whole experience is seeing humanity do what I think it’s best at, which is not competing, it’s cooperating.” At the moment, Green looks less pied piper and more Mr. Rogers, another figure who turned down ministering in a church to make people feel special. And as Green races from project to project, working relentlessly in every medium to bring in outsiders, it becomes abundantly clear: This guy knows what it means to be a good neighbor.

This story originally appeared in mental_floss magazine. Subscribe to our print edition here, and our iPad edition here.