Any good marketer today knows their brand isn't their own -- it belongs to its fans. But living that philosophy takes a bit more fortitude for some brands than for others.

Evidence The Hub.

In October, the kids' cable network, partly owned by Discovery and toymaker Hasbro, reimagined "My Little Pony," a cartoon that had its roots in the 1980s, when Hub CEO Margaret Loesch was CEO of Marvel Entertainment and executive producer of the program. The new series, "My Little Pony: Friendship Is Magic," drew, as intended, many viewers aged 2 to 11. But a funny thing happened on the way to Ponyville: Adults also started watching, including a male teen-and-older demographic of webheads that go by the name of "bronies."

Praise for the series, created by Lauren Faust ("Power Puff Girls"), started bubbling up on chat board 4chan, and almost overnight the show became a cult internet phenom, spawning hundreds of YouTube mashups, memes, fan fic and dozens of pony fansites, including Equestria Daily (so named after the kingdom the ponies live in), that as of today has garnered more than 71 million hits. There are podcasts called Bronyville and a Big Apple gathering, BroNYCon, in which the faithful come to mingle with the show's voice-over actors and composers of such show songs like "Art of the Dress." As word spread virally, show viewership doubled between seasons one and two.

The Hub could have distanced itself from this but, to its credit, did not. The show "is popular with kids and a loyal group of adults, and we tried to embrace that ," said Ms. Loesch.

And so, with a wink, the show has written in subtle pop culture references to things like "Chocolate Rain" and "The Big Lebowski." What really tickled the bronies, however, was a YouTube takeoff on Katy Perry's "California Gurls" called "Equestria Girls" that calls them out: "our bronies know we're awesome fillies."

"We decided to salute and embrace all the viewers who have embraced our brand," said Ms. Loesch. Or, in the show's parlance, "everypony."