Two of the most consequential figures in the Trump legal soap opera have been a pair of Justice Department officials whose names the public wouldn’t typically know. The first is Deputy Attorney General Rod Rosenstein, who has run into one politically charged dilemma after another since being thrust into the role of supervising the FBI’s Russia investigation. The other is Rosenstein’s predecessor as deputy attorney general, Sally Yates, who became an icon of the anti-Trump resistance before being fired by the president in the wake of her refusal to allow the Justice Department to defend Trump’s travel ban.

Yates and Rosenstein have more in common than the sudden and unexpected fame they’ve both attained amid the turbulence of the Trump era. The DOJ officials have also shared an adviser, a former prosecutor from South Carolina named Scott Newton Schools. As the senior-most career attorney at the Justice Department, Schools is responsible for helping the deputy attorney general—the person who runs the DOJ on a day-to-day basis—in navigating the agency’s hardest, most sensitive problems and spotting potholes on the road ahead.

Schools is “the most important unknown person in D.C.,” said Gregory Harris, a defense lawyer who served alongside him in the U.S. Attorney’s Office in South Carolina. And while Schools’ job is one that “almost nobody outside of DOJ knows about or understands,” in the words of Obama-era DOJ official Kathryn Ruemmler, it has never been more crucial to maintaining the department’s stability.

Schools’ official title is “associate deputy attorney general.” There are five others in that position, and while on paper Schools doesn’t outrank them, the reality is that he was hired by Yates in October to be a leader—someone who would operate as an apolitical civil servant at the highest echelon of the department and provide counsel in times of tumult.

Over the past week, I’ve tried to find out exactly what kind of advice Schools has been giving Rosenstein and how much Rosenstein has relied on him while thinking through the high-stakes predicaments that have come his way. I’m not too proud to admit I’ve failed in this effort: The Justice Department declined to make either Schools or Rosenstein available for an interview.

However, according to multiple ex-DOJ officials I’ve spoken to, it’s undeniable that Schools, who is 55, has been better positioned than anyone else to help the deputy attorney general make numerous critical decisions. Those include Rosenstein’s move to appoint a special counsel to take over the Russia investigation—and to tap former FBI Director Robert S. Mueller III for the job—as well as Rosenstein’s own deliberations over whether he should recuse himself from the investigation. Given Rosenstein’s avowed respect for the DOJ’s career staff—as well as the fact that he only recently brought on a permanent chief of staff and a top political adviser—it would be surprising and dismaying, ex-DOJ officials told me, if he wasn’t seeking input from Schools.

“Scott Schools working closely with Rod is very reassuring,” said Julie Zebrak, who served as deputy chief of staff to Deputy Attorney General James Cole from 2013 to 2014. “Those of us who know them and who are watching what’s happening from the outside have a tremendous amount of faith that they will … preserve the integrity of the department and ensure the rule of law is observed.”

The main reason Schools is suspected to be at the center of the action at DOJ is that the man who preceded him as the agency’s top career lawyer was a figure of such unrivaled stature and influence. David Margolis, who died in July at the age of 76 after 51 years at DOJ, was the quick-witted and even-keeled Yoda of Justice—a trusted fixer who helped resolve the agency’s stickiest, most delicate situations, among them ethical and disciplinary problems involving DOJ employees. Schools has essentially inherited that job, as well as all the grand expectations that come with it.

“If you could say the institution of the DOJ was embodied and exemplified by one person, I think David was that person to a lot of longtime DOJ veterans and alumni,” said Matthew Axelrod, who served as Yates’ top deputy and left the department to join a private law firm a few weeks into the new administration. “He was known as someone who was there to guard the department’s institutional integrity and reputation, both sort of behind the scenes and externally.”

It was up to Margolis to decide whether John Yoo, a Bush-era political appointee in the Office of Legal Counsel, would be sanctioned for providing the administration with a legal defense for waterboarding and other forms of torture. (Overruling the conclusion of DOJ’s Office of Professional Responsibility, Margolis declared in a controversial report that Yoo’s actions did not rise to the level of professional misconduct.) He was also assigned the sensitive task of inspecting Vince Foster’s office after the Clinton aide’s 1993 suicide.

Margolis’ death left a gaping hole at the DOJ that Schools must now fill. In many ways, this was his destiny: When Schools first joined the leadership team at Main Justice—the Washington D.C. headquarters of the DOJ—in 2008, Margolis became the younger lawyer’s mentor and master. “I know for a fact that David Margolis shaped Scott’s legal life more than anybody else,” said Harris, Schools’ longtime friend and onetime colleague. “David had lived through every controversy that DOJ had gone through in the past 30 years,” added Ruemmler. “So he was this incredible source of institutional knowledge, and he really worked to impart that institutional knowledge to Scott.”

At the time of Margolis’ death, Schools had left the Department of Justice, having moved back to South Carolina and gone into private practice as a defense attorney. He had represented, among others, the state’s longest-serving sheriff, who stood accused of accepting bribes from a local businessman. Schools and his co-counsel negotiated such a good deal with the state—no jail time for the defendant—that the judge rejected it. (The sheriff ended up being sentenced to a year in prison.)

In the fall, about four months after Margolis’ passing, then–deputy attorney general Yates succeeded at coaxing Schools back to Washington to fill his mentor’s shoes. “When David passed away, there was only one choice for his replacement, and that was Scott,” said Heather Childs, who served in the deputy attorney general’s office during the Obama administration. “We immediately did everything we could to bring him back.” As Axelrod noted, Schools has “lived through so many difficult things, unusual things, [that] when you have an unusual thing, when there’s no real playbook on how to handle it, you can talk to [him].”

As an heir to a grocery store fortune, Schools could’ve chosen to pursue a life of leisure. (“If my grandfather had started the Piggly Wiggly [Carolina Co.] grocery chain, my ass would be in the Bahamas,” said Bill Nettles, a former prosecutor in South Carolina.) Instead, the Duke University and Texas School of Law grad chose to become a prosecutor, going to work as an assistant U.S. attorney in Charleston, South Carolina in 1989. He was in his late 20s but looked so young that people called him Doogie Howser. (Close friends still call him Doogie.) Almost immediately, he was assigned to work on what ended up being the highest-profile public corruption case in the history of South Carolina. By the time it was over, the bribery sting “Operation Lost Trust” had taken down fully 10 percent of the state legislature. Last year, the State remembered the shameful affair, in which law makers were caught on video taking $100 bills in exchange for votes, as “a line of demarcation in South Carolina government, a point from which we date events ‘before’ and ‘after.’ ”

The biggest—or at least most high-profile—case of Schools’ career was one he prosecuted in California, while serving on an interim basis as the U.S. attorney in San Francisco from 2007 to 2008. In that capacity, Schools signed off on an indictment against Barry Bonds on four counts of perjury and one count of obstruction of justice. The charges stemmed from grand jury testimony that Bonds had given in 2003, when he stated that he had not knowingly taken steroids. When a jury convicted Bonds of obstruction years later—while deadlocking on the more serious perjury charges—the verdict came in for criticism from civil liberties advocates as an example of dangerous prosecutorial overreach. (Bonds’ conviction was later overturned by the 9th Circuit Court of Appeals.)

Schools’ friends and colleagues in South Carolina speak of him with great reverence, but show an almost comical commitment to describing him in vague platitudes. “He’s got a nice touch with people. He’s smart as could be,” one lawyer told me. “His favorite saying is ‘keep your eye on the ball,’ ” said another. A third said, “He’s smart, dedicated, capable—all the adjectives you would use to describe a really dedicated, smart, capable federal prosecutor.”

What shines through this cloud of generic compliments is trust: Everyone who has worked with Schools seems confident that he always does what he says he’ll do, thinks carefully about the difference between right and wrong, and never tries to get away with anything. “Scott was someone who anyone could go to get an honest assessment,” Roy Austin, who served in the Obama-era Civil Rights Division, told me via email.

Last year, Schools’ old colleague Brady Hair, now the city attorney for North Charleston, South Carolina, enlisted him in the city’s efforts to respond to the police shooting of Walter Scott. “We consulted on a daily basis about things that were going on and how best to respond and how to handle it,” Hair told me. “Scott [Schools] was an integral part of a team of lawyers that I put together, and that I believe successfully handled a potentially volatile situation such that it didn’t erupt into the kind of violence that occurred in other parts of the country.” (In May, Michael Slager, the officer who killed Walter Scott, pleaded guilty in federal court to “deprivation of rights under the color of law” after a criminal trial in South Carolina ended in a hung jury.)

It doesn’t take anything away from Schools to point out that he does not enjoy the same legendary status within DOJ as his predecessor. For one thing, he has less experience than David Margolis and therefore a less encyclopedic institutional memory. For another, he does not carry himself with Margolis’ irresistible swagger: There are no stories about Schools wearing pink leisure suits and bell-bottoms to work as a younger man, no institutional lore about the days when he would smoke cigarettes in his office, and no catalog of famous Schools-ian quips. (Asked at a congressional hearing how many people worked at the DOJ, Margolis famously replied, “About 60 percent.”)

“They were very good friends, but everybody sort of joked that they were the odd couple,” said Childs, who worked with both men. “Margolis was jovial and extroverted … and he enjoyed his food and his wine and made crass jokes. Scott was much more quiet, reserved, and straight-laced.”

One significant difference between Margolis and Schools is that the former never let anyone know what party or candidate he supported, whereas the latter is clearly a conservative. According to public records, Schools was registered as a Republican as recently as 2008, and during the 2016 Republican primary, while he was working in private practice, Schools signed an endorsement of New Jersey Gov. Chris Christie for president. “I’ve always understood him to be a Republican,” said Roy Austin, the former Civil Rights Division official.

Schools’ former colleagues from Main Justice reject the notion that he brings his politics to work. Kathryn Ruemmler, the Obama-era DOJ official who worked with Schools in the deputy attorney general’s office from 2009 to 2010, said that based on his actions at DOJ, she had “no idea if he was a Democrat or a Republican or independent.” Lawyers in South Carolina further emphasized that Schools worships the DOJ and can be trusted to place the institution’s interests above any partisan concerns. “There was an emptiness that he felt” when he was in private practice, said former U.S. Attorney Bart Daniel, who hired Schools for his first prosecutor job and later started a law firm with him. “He yearned to be back in the public service sector, and in the Department of Justice specifically.”

Now that he’s back, Schools, who has never been married and does not have children, is said to be focused on his job to the exclusion of everything else. “If you followed him around,” said Brady Hair, the city counsel for North Charleston, “I think what you would see is that he gets up in the morning, he gets to DOJ, he stays there until late, he goes home and eats dinner … then he goes to bed and gets up and goes to DOJ.”

If the ex-DOJ officials I spoke to are correct, then a lot of Schools’ time at the office is likely being spent helping Rosenstein deal with the White House and all the unpredictable and destabilizing issues that have arisen in connection with the Russia investigation. Rosenstein has made a number of fateful moves already—writing his infamous Comey memo, for instance—and as the Mueller investigation continues and potentially expands, he’ll have to make a whole lot more. Whatever happens next, it’s a good bet Rosenstein will have Scott Schools whispering in his ear.