Helen Klein Ross established herself as a writer and creative director at top ad agencies like FCB and Ogilvy, but in the last five years she’s reinvented herself as a social media renegade.

In 2007 she launched AdBroad, an AdAge Power 150 blog covering her corner of the advertising industry. Then, at SXSW 2009, she coined the term “brand fiction” to describe her unique hybrid of branded entertainment and fan fiction and launched a boutique content agency, Brand Fiction Factory, shortly thereafter.

The idea behind brand fiction is to give brands a life of their own on social media channels, growing the brands’ mythology along with their number of followers.

Her unofficial, Webby award-winning @bettydraper Twitter feed tops out at 31,000 followers, illuminating the inner life of the fictional 1960s housewife in AMC’s Mad Men.

Other Mad Men characters have Twitter profiles as well (some voiced by Ross, some by other fans), creating an ongoing conversation that draws on the show’s plotlines. This develops their personalities while giving new and die-hard fans something to chew on between episodes.

But “Mad Men on Twitter” extends beyond Twitter. Klein Ross and her cohorts even put together a Twepisode titled “Don takes Sally to the Beatles” that imagines how the characters in Mad Men would have experienced the legendary Beatles concert at Shea stadium if Twitter were around in 1965. There’s also a blog, Welcome to the Drapers. (Mad Men’s creator, Matt Weiner, and AMC have given their blessings but declined to officially endorse the project.)

During this year’s StoryWorld Conference in San Francisco, Sparksheet editor Dan Levy caught up with Helen Klein Ross, who explained what brand managers and TV producers stand to gain by bringing some fiction (and fun) to their brands.