We are sitting at one corner of his sprawling complex of offices, just a few blocks from the U.S. Capitol, where he employs 250 youthful activists to dig dirt on Republicans, plant stories in the press and punish pundits who step out of line. They work for groups with bland names that conceal their importance–Media Matters, Correct the Record, American Bridge, American Democracy Legal Fund, to name a few–on two floors that don’t look anything like a D.C. political office.

Think Cupertino startup meets Buddhist retreat meets the Jetsons, with bright molded-plastic furniture, exposed ceilings, colorful art, the occasional Japanese paper wall. Brock doesn’t look anything like a D.C. operative, either. At 53, he wears his silver hair long and pomaded behind his ears; he likes tailored shirts that fit too tight, pocket squares and skinny ties. When he drafted the office lease, he wrote in a clause for Toby, the pet schnoodle who accompanies him to work.

The question is simple and should be easy. When was the first time you saw Hillary Clinton after you defected from the conservative movement? He’s told the story before; it all happened more than a decade ago, for God’s sake. But his voice is halting. Then it cracks.

It was a Senate lunch in 2002, he says, just after he had published his third book, Blinded by the Right, a confession of all the rotten things he had ever done to liberals–from his “little bit nutty and a little bit slutty” slander of Anita Hill, who had accused then Supreme Court nominee Clarence Thomas of sexual harassment, to his discovery of Paula Jones, which forged a trail to Bill Clinton’s impeachment.

In an ornamented room, he told the Democratic leaders about their right-wing enemy, talking for nearly an hour. Clinton, then a Senator, sat in the back, immobile, hard to see over all the balding heads and charcoal suits. “She didn’t say anything, so I was starting to wonder,” he says. “And her hand went up at the very end.” This is where he starts to lose it. “And … she just summarized everything I said. Better than I said it. And it was amazing.”

I ask if something is wrong, if he is really as emotional as he appears. “Yeah,” he says. “It was a big deal.”

Now Hillary Clinton is rising again, along with the scent of scandal and the frenzy of her enemies, and Brock has pledged to fight by her side. To understand his commitment, you must first understand the most bizarre entanglement in modern political history, which has turned Brock into one of the most powerful players in Democratic politics. Among other jobs, he currently coordinates message strategy with the Clinton campaign, leads her rapid-response super PAC, raises money and sits on the board of a separate “independent” super PAC that will pay millions for her TV ads, and has set up the group that creates all the federal Democratic opposition research for the 2016 campaigns.

In total, over a little more than a decade, he has personally raised more than $150 million from rich liberals to fund his sprawling empire, which also includes a group that files mostly spurious ethics complaints against Republicans and another that mercilessly attacks both Fox News and the New York Times. This is no small feat for a reformed liar who has never held political office. And to hear his defenders tell it, he has done it all with aplomb.

“Brilliant,” several of them tell me when I ask about Brock’s talents. “He’s like a minister,” says John Stocks, the chairman of the Democracy Alliance, an umbrella group for wealthy progressives. “He is like an artist in my mind,” explains Susie Tompkins Buell, a progressive activist, Clinton supporter and Brock’s first major donor.

But talent is not all Brock has. His relationship with Hillary Clinton is at the root of everything he has accomplished. Salvation came first to Brock, who in 1994 found himself suicidal, sitting in a running Range Rover in a closed garage in Laguna Beach, Calif., suffering for the lies he had peddled about Anita Hill. He stepped out of the car and into his next project, a takedown biography of Clinton, which had earned him a $1 million advance. But instead of writing what everyone expected, he wrote the truth as he saw it, a glowing tribute to a courageous woman. “In struggling to find Hillary’s humanity, I gradually found my own,” he explains in his latest book, Killing the Messenger, due on store shelves Sept. 15.

Salvation came to Clinton years later, after her husband’s affair with a 22-year-old White House intern became a national disgrace. As the furor grew, Brock, who remained a member of the conservative elite, became her eyes and ears, a secret agent feeding the White House real-time intelligence by way of Clinton adviser Sidney Blumenthal. Brock detailed it all, from the leaks coming from the independent prosecutor’s office to the secret sources of Internet bad boy Matt Drudge.

When Clinton went on NBC’s Today show in 1998 to warn the country of a “vast right-wing conspiracy,” she was describing a picture Brock had painted. It was Hillary who kept a chaotic White House focused on its tormentors that year, and it was Brock who gave Hillary the ammunition. “Having knowledge restored a sense of normalcy,” Blumenthal would later write of Brock’s contribution to Hillary during those dark days.

Over time, both Bill and Hillary Clinton found they shared something else with Brock: an unnatural focus and fierceness. “What I appreciated from the right wing was you had to have political power before you could make the changes you wanted to make,” Brock explains now. “And I wasn’t afraid of that. There was a culture in the Democratic Party of weakness and nonresponse. I think some of what we did helped change that culture.”

Political knife fighting turns out to be far more complicated than the real thing. The best practitioners conceal not only the knife but also the fighter. They distort the truth without getting caught in a lie. Most important, they submerge their cutthroat instinct in a redemption story, a fight for justice and goodness, which allows people to believe in the cause–and in the need to shed more blood in its name.

Brock has such a story. Last year he traveled to the Clinton Presidential Library in Little Rock, Ark., to make his case that the person he used to be still exists in the conservative firmament. The dark enemy would return. “I know from personal experience that the best efforts of the right wing to market political smut did not defeat the Clintons,” he said. “The truth won out in the end. And it will again.”

This time, he promised, the fight will not play out as it did before. If the New York Times stumbles in a Page One story on Hillary’s email scandal, Brock is there, penning a letter demanding an editorial “review” of the paper’s “flawed and fact-free reporting.” If Jeb Bush takes a dig at Hillary for failing to promptly turn over her emails to the government, Brock’s deputy asks the Florida state attorney to open a criminal investigation into Bush for his possibly “knowing and willful” violation of Florida public-records laws. If Trey Gowdy, the head of the House Select Committee on Benghazi, asks for Clinton’s personal server, Brock counters with an open letter to Gowdy demanding the public release of “your own work-related and private email.”

Candidates have long sent kids to track their rivals with video cameras, hoping to capture a public slip-up. But Brock’s operation is the first to have a team of about 30 trackers live-stream the footage back to headquarters so that it can be more quickly cut and sent out to reporters. He has also begun to plot new ways to get his trackers more involved–in asking questions of Clinton’s rivals, perhaps even setting up dummy groups so they can buy their way into fundraising events.

Such undercover work, a trademark of conservative activists since the Nixon era, has lately been frowned on by liberals. “I am very aware of what the Democratic culture will tolerate,” Brock says. By this he means he continues to push for change, though he maintains that he will never return to peddling falsehoods. “If people understand what propaganda is,” he says, repeating a koan of his craft, “it ceases to have an effect over time.”

As time has passed, the Brock trophy case has grown. By creating bursts of outrage, he helped get Don Imus kicked off MSNBC, ended Lou Dobbs’ run at CNN, chased Fortune 500 advertisers away from Rush Limbaugh and organized a boycott of Glenn Beck’s Fox News show before its cancellation. A local Brock tracker was the first to uncover Missouri Senate candidate Todd Akin’s bizarre comment about “legitimate rape” in 2012, and his opposition research helped ensure that Tea Party candidate Richard Mourdock won the Senate primary in Indiana, thus ensuring a Democratic pickup in the general election.

Chances are your views on Charles and David Koch, the biggest backers of conservative politics, have been shaped more by Brock’s research machine–which paints the brothers as greedy moneybags with selfish interests–than by their own multibillion-dollar operations. Before he entered the race, Jeb Bush was tripped up on camera over a question on his support for the Paycheck Fairness Act, a Democratic effort to increase wages for women. Brock’s people not only recorded the exchange, they also planted the question. Back in 2010, he even wrote a secret memo proposing the impeachment of Justice Clarence Thomas, a radical idea that Blumenthal forwarded to Clinton. “After the ’13 and ’14 cycle we went back and we measured the TV coverage of any piece of research that was original to us,” Brock says. “And we monetized it as if you went out and bought it as advertising. It was over $225 million in publicity, and we spent $15 million to produce it.”

Ask Brock where it ends–this constant innovation, the institutional expansion–and he gives an ice-cold answer. “The only place it can end is with the defeat of the extreme elements of the Republican Party,” he says. “A third of the Republican base thinks Obama is the Antichrist. You just can’t reason with them.” This is the language of zealots who welcome peace talks only after the total surrender of their rivals. I point out that most liberals would not talk like that. “Probably not,” he agrees.

Last January, some Democratic opponents of Brock attempted a sort of palace coup. They didn’t like his growing power, didn’t like his fundraising methods–his business partner earns a commission on nonprofit donations, an unusual practice–and they wanted to maintain the Obama hold on the party’s richest donors. A disparaging story appeared in the New York Times, detailing the complaints, and Brock abruptly quit the board of Priorities USA, the Clinton advertising effort, threatening a rift in the high-dollar Democratic-donor community. “This is the kind of dirty trick I’ve witnessed in the right wing and would not tolerate then,” Brock wrote in his resignation letter.

Within weeks, Hillary Clinton’s allies stepped in, and Brock won back what he wanted, almost completely. Obama insiders were dispatched and demoted, a Clinton confidant was put in charge of the organization, and Brock was invited back to the board, with the promise of a joint fundraising plan he had long proposed. In the coming months, even as he advises the campaign, he plans to raise millions for a joint fund, which will split its money with the pro-Clinton group he founded. Not much has been raised yet, but hopes are high. “I think we came up with 800 donors who could give $1 million or more,” he says. “That doesn’t mean they will. But they could. So that’s not a terrible number.”

As for the current scandals swirling around Hillary, he refuses to give an inch. On the private email server: “I don’t feel any criticism is due.” On the Clinton Foundation’s raising money from people Bill Clinton helped through public appearances overseas: “The attacks on the foundation are almost the most despicable because of all the good work the foundation does.” Any reason for concern over the creation of a private consulting firm, Teneo, that employed Hillary Clinton’s State Department aides while aiding Clinton Foundation donors? “No. I haven’t seen anything,” he says.

This is David Brock. When he thinks of Hillary, he doesn’t think about an awkward politician with a mechanical laugh who has lost as many public battles as she has won. He thinks of the “deep well of personal integrity” he wrote about in his 1996 book. He thinks about the time she invited him to the Clinton summer rental in Sagaponack, N.Y., when her whole family was there, the siblings, spouses, kids and dogs. He thinks about eating pizza and sipping soft drinks by the pool, then looking up after a couple of hours to see the Secretary of State walking around the yard with a trash bag, picking up garbage. “Just like something my mom would do,” he recalls.

Does that sound like propaganda to you? You could call it that. Or you could call it politics. But for David Brock it is also the truth, a lodestar for the person he has become.