By Shelley DuBois, reporter

Dropping a plot twist like a time traveling island to millions of obsessed viewers requires a different skill set than, say, reporting your first quarter earnings. But at the end of the day, it’s all business.

If that sounds like crazy talk and not the focus of your life for the past six years, you probably haven’t heard of Damon Lindelof, one of the writers of Lost. But you’ve probably heard of Lost. The six-season smash hit kept an average of 13.5 million viewers per year tuning into ABC, and a couple million watching online, downloading video on demand or buying DVDs.

Lindelof and Carlton Cuse took over the show after the first season, when J.J. Abrams ditched for other projects. Lindelof will be speaking at Fortune’s 2010 Brainstorm Tech Conference in Aspen. Hopefully he’ll share some insight about how to top his last TV mammoth, and how to use other media to successfully prop up a broadcast show when broadcast in general looks sickly.

When Lost started six years ago, it pretty much pioneered the nexus between social media and television. In retrospect, it seems necessary to the show’s survival. Lost probably wouldn’t have worked as broadcast-only—the plot is too tangled to jump back in after missing an episode. Also, Lost tapped into the realm of loyal nerdom that fostered followings for sub-cultural icons like Dungeons and Dragons, Star Trek and the Watchmen. This generation’s trekkies could recap and speculate about episodes in online communities.

Lost spawned fan sites, discussion groups, and its own open-source encyclopedia. It’s generated merchandise in the physical world too: books, action figures and cookies modeled after the ones that characters ate in a time warp. If you watched the show online, you could watch it with subtitles, pop-up-video style, to guide you through tangles in the plot. Viewers scanned episodes religiously, looking for clues in numbers that reappeared in episodes. Three guys in New York watched all 120 episodes of Lost back to back leading up to the finale, for charity. Damon Lindelof tweeted about it.

Which is another force that the writers had to contend with—viewers now expect a dialogue, along with a complex narrative. They develop a relationship with the characters and the story, sure, but also the writers and the actors. Lindelof has 72,377 followers on twitter. He and Cuse responded to viewer questions through a variety of media. It’s hard to imagine that user response didn’t partially shape the show.

And that’s the challenge that Lindelof mastered—how to make a hit sci-fi television series in an age where television is dead. It’s the biggest secret of the whole series.