Bronies are on the march. One of the strangest, most volatile fanbases on the internet has exploded over a tiny change to a beloved character on the children's cartoon "My Little Pony."

Adult fans of the new Hasbro animated series "My Little Pony," have become the most visibly fanatic of the many strange fan communities on the internet. Thousands of (mostly male) nerds calling themselves Bronies spread their unironic love of MLP, as they abbreviate it, over Twitter and dozens of dedicated message boards and blogs. Bronies started on 4chan's anarchic /b/ board as an inside joke before mutating to a very sincere fandom. And like Anonymous, 4chan's other notorious hive mind, Bronies have adopted online collectivism with astonishing effectiveness—only focusing their hive mind on creating MLP fan art instead of crashing U.S. government websites.

So whenever a controversy erupts in the bronysphere, it goes full Krakatoa.

Currently, the Brony hive is waging the "Save Derpy" campaign, after show creators slightly changed a favorite character was changed slightly to be less suggestive of a person with a mental disability.

Of all the ponies in My Little Pony's fantasy kingdom of Celestia, none is more beloved by the Bronies than Derpy, because they created her. Derpy began as an unnamed background character in the first episode of the series whose eyes had been skewed by an animator as a joke. Fans seized on the weird horse, and named her. As a nod to the Bronies' role in the show's success, the animators included her in episodes with increasing prominence.

"It's great fun to sift through a new episode to see if the animators have stuck her pony model in a crowded scene for us to find," said a Brony who goes by the name Cereal Velocity and who serves as an editor for the Brony news blog Equestria Daily. "It became a weekly game and everyone involved with it had a lot of fun. Everyone in the community has a different interpretation of her character since she was never assigned one in the show—in essence, she was the community's pony."

Derpy's big moment, and her first lines on the show, came at the beginning of January in an episode called "The Last Roundup." ("Oh, I just don't know what went wrong!" Derpy says, as she clumsily tries to set up for an upcoming party.) It was Bronies' greatest triumph: A fan-created character on their beloved show. A video captures the flood of "ZOMG!!!" and "DERPY!!!!" in an MLP chat room where Bronies had assembled to watch the show live. (Incredibly, this video now has 139,828 views.)

But Derpy's new prominence also reignited a controversy simmering beneath the Bronysphere over whether or not Derpy's appearance and behavior were offensive. Some fans have claimed Derpy is one "giant retard joke": Derpy's name comes from 'Derp,' internet slang that started on message boards in the early 2000s and means something is stupid. Whether "Derp" explicitly mocks people with mental disabilities has been endlessly debated. But it's definitely related to those "retard" sounds idiot kids make at each other in high school halls, and it's disproportionately used to refer to people with mental disabilities in general and people with Down Syndrome in particular. (The Anonymous hackers who hit Gawker a couple years ago illustrated this.)

Hasbro, which has had a sometimes-rocky relationship with Bronies, sided with the Derpy critics. They replaced the episode on iTunes with a cut where Derpy's voice was changed to sound less dope-y, and her name was removed altogether.

"The 'My Little Pony Friendship is Magic' series has always been about acceptance and inclusion, and the series strives to convey that through the playful antics of a diverse cast of characters," Hasbro spokeswoman Nicole Angello told us over email. "Some viewers felt that aspects of the episode 'The Last Roundup' did not stay true to the core message of friendship which is the heart and soul of the series. Hasbro Studios decided to make slight audio alterations to this single episode."

Bronies did not agree. A petition on Change.org—usually home to campaigns about gay rights and debit card fees—has garnered nearly 40,000 signatures on a plea to "Return Derpy's scene in the Last Roundup to normal." The fan video to the left, which has over 150,000 views, stoked the tearful anger of the Bronies, who flooded every Hasbro employee they could find with pleading emails.

The hive mind also turned vengeful. They focused on one dedicated Derpy critic, a woman who goes by the name Yamino and who had written a number of Tumblr posts about Derpy's "ableism." The My Little Pony board on 4chan launched a raid on her Deviantart page. Here's just a sample of the abuse:

FUCK YOU DIE SHIT FUCK DIE BALLS YOU MOTHERFUCKER. WHY THE FUCK IS WRONG WITH YOUR STUPID BIMBO MOTHERFUCKING FACE DIE FUCK AND CUNT BURN DIE I FUCKING HATE YOU.

It got so bad that one of the show's animators had to take to his own blog and call off the mob.

Bronies have become a rather unlikely internet powerhouse, but it's unlikely they'll persuade Hasbro—who must feel both blessed and cursed by a fanbase as entitled and obsessed as that of any adult sci-fi series or comic book—to restore their beloved Derpy.

Cereal Velocity, of Equestria Daily, takes the long view: "This whole situation has been sort of depressing for most of us, but I think the best thing people can remember is that Derpy isn't the reason the show is awesome.

"The show," he explained, "is just awesome."

Photo by Ronald Hennessy via flickr.