Anonymous and LulzSec are planning something called "Payload #1" for Friday. It's the first major event for the two hacking groups' new activist-oriented collaboration, Operation Anti-Security, or AntiSec. But in a roundabout way, it's sort of a reunion for the two groups.

In a sprawling exposé out Thursday, The Wall Street Journal explains how the two groups trace their roots back to 2003 and prank-planning on 4chan, an anonymous image forum where the shenanigans of a small group of users got out of control. That collective became known publicly as Anonymous after an attack on the Church of Scientology made headlines. Following other high-profile hacks on PayPal, Sony and HBGary, an internet security firm that was secretly investigating WikiLeaks, a splinter group calling themselves LulzSec emerged with a more voracious appetite for aggressive assaults on major corporations and banks as well as national governments and spy agencies. Their ruthless and apparently unrelenting attacks on any secure target they deem laughable--"Lulz" stands for laughs, "Sec" for security--launched the group into the global media spotlight. Just after LulzSec announced joining forces formally with their old pals at Anonymous, kids started getting arrested.

Earlier this week, British police took into custody a suspected LulzSec ringleader named Ryan Cleary. The 16-year-old had been connected to hacking into the encrypted chatrooms of Anonymous, which then published his contact information, surely a strong lead for investigators scrambling to find anybody connected with the hacker groups. Though the media eagerly linked Cleary to LulzSec after police drew the connection to Anonymous, both groups have denied that Cleary held a leadership role. This arrest follows that of 19-year-old Martijn Gonlag, the hacker featured in WSJ's history of Anonymous, who admits to have taken part in attacks last year. Since his December arrest, Gonlag has grown disenchanted. Gonlag and other say the group's decentralized nature is a problem for everyone.

"People are starting to realize that Anonymous is a loose cannon," Gonlag told The Journal. Other sources told the paper that Anonymous is really more of "an idea" than a formal organization. This is a big problem for the law enforcement agencies trying to find the culprits in the many recent attacks on companies and governments. The groups are primarily young males--from teenagers to men in their early thirties--and many suspect the leadership of each to be five to ten that communicate over encrypted chats. "There is no one group, no one website," another Anonymous collaborator Gregg Housh said. "That is what makes it so powerful in my eyes."

The reunion of LulzSec and Anonymous could provide police with clues that could lead to more arrests. But as hacking expert and New York University professor Gabriella Coleman told The Journal, it doesn't really matter. "There are nodes of power and authority, but it is pretty decentralized, and no one is calling the shots for all the operations."

It sounds like the multi-headed Hydra. In Greek mythology, Hercules had to kill the Hydra as one of his Twelve Labors, but this proved challenging, as every time he cut off one of the heads, another would grow in his place. Eventually, he realized that burning the stumps closed to stop it from regenerating. The F.B.I. so far looks hardly Herculean, though. A Tuesday raid on a server bank in Virginia so far succeeded only in knocking out service to the Curbed Network and Instapaper. LulzSec tweeted after the fact, "Best watch out, they can't get us, so they're going after people they think might know us. Defend yourselves."