Six months into the dumpster fire of Elon Musk’s ownership of Twitter, in which the social media company has lost more than $20 billion in value, some are hailing the appointment of new CEO Linda Yaccarino as the billionaire’s last best hope of salvaging this misadventure.

“If I were a stockholder in Twitter, and I were gonna sell my stock yesterday, I would keep it today based on the fact that Linda went there,” a media industry insider who has worked with Yaccarino for several years told Fortune.

But whether Yaccarino will manage to turn around the company’s fortunes depends on her ability to tame its unruly owner. How this will play out is the subject of fevered speculation: Is it a “glass cliff,” in which a woman leader is brought into a can’t-win predicament? Is Musk looking for a responsible, maternal figure to play the foil to his impishness, a la Gerri Kellman?from Succession? Or has Musk finally brought in a leader with the spine to stand up to his whims?

Those who have encountered Yaccarino during her dozen years as an ad executive at NBC, and nearly 20 years at Turner Broadcasting System, say she’s a force to contend with in her own right. Yaccarino is not a typical executive, and her background and tenacity could set the stage for one of the unlikeliest of comeback stories. “I’ve long been inspired by your vision to create a brighter future,” Yaccarino tweeted about Musk on May 13, in her first public acknowledgment of accepting the CEO job. “I’m excited to help bring this vision to Twitter and transform this business together!”

Fortune spoke to seven people who have worked closely with Yaccarino in order to get to know the woman who Musk is counting upon to lure back the advertisers who have fled the increasingly toxic social media platform.

A fearless leader in a male dominated industry, who leads her team through intense SoulCycle sessions

In an industry full of strong personalities, Yaccarino stands out for her grit. During her three decades in the media and ad industry, Yaccarino, a native of Long Island, New York, has sparred with ambitious, internal rivals, managed relationships with demanding clients, and spearheaded high-stakes industry battles over ad measurements.

She “has driven some of the best relationships on the client side and the agency side of anybody I’ve ever seen,” said Michael Kassan, CEO of MediaLink, as well as a friend and colleague of Yaccarino for over two decades. “She embraced technology, really embraced the understanding of the cross platform opportunities early,” he added, highlighting what could be an important skill as Yaccarino makes the transition from television media to social media.

Known for being a sharp-dresser—she’s often seen in thick framed glasses, stylish heels, a colorful power suit to match—and for her confident demeanor, Yaccarino is easy to spot in a crowd. That’s especially the case because, according to one source, the staffers surrounding Yaccarino often adopt her fashion style and her mannerisms. The bonds within Team Yaccarino are reinforced during intense SoulCycle sessions that Yaccarino leads and to which favored employees are invited. Loyal staffers are often rewarded with promotions (not always merited, one source snickers), and indeed there are already rumblings that Yaccarino is looking to poach employees from NBC. According to Bloomberg, NBCUniversal ad executive and Yaccarino deputy Krishan Bhatia may follow his boss to Twitter.

Sources describe Yaccarino as a “tough,” traditional Italian, “Long Island lady” who can both inspire and terrify the people who work for her. She has an identical twin, who’s a nurse.

Her fearless attitude in the male-dominated ad business is undoubtedly one of her biggest strengths, and could be an important part of her professional relationship with Musk. She’s capable of playing the long game, said a source, describing her rise at NBC: “She came in knowing that she was going to run the whole thing, but she started with cable and she took over broadcast.” Two sources also told Fortune she’s a sharp negotiator, which will help her when it comes to crafting a smart employment contract with Musk.

“She stood up to a lot of misogyny. She stood up to a lot of men,“ the source recalled during her time working with Yaccarino. “There’s nothing demure about her.”

Her values are well documented, too. She’s a devoted Catholic and staunch Republican. When former president Donald Trump was elected to office, Yaccarino attended his inauguration, one source told Fortune. Then, in 2018, Trump appointed Yaccarino to serve a two-year term on the President’s Council on Sport, Fitness and Nutrition, alongside big names like New England Patriots head coach Bill Belichick and Incredible Hulk star Lou Ferrigno, Adweek reported. One source said she joined “just to get near Trump.”

Some have speculated that Musk chose Yaccarino because their political values aligned. Yet, according to Lou Paskalis, CEO of the marketing consultancy firm AJL Advisory, and a client of Yaccarino’s for 35 years, Yaccarino always kept her political views “fairly private.” That sensibility could provide the needed counterweight to Musk’s tendencies, Paskalis reckoned: ”She’ll probably be able to temper [Musk’s] enthusiasm for extreme commentary, but introduce more balance.”

How do you solve a problem like Elon?

Yaccarino’s relationship with Musk appears to be relatively recent, with many observers pointing to an on-stage interview she conducted with Musk in April at a Miami conference as a key moment.

During the talk, entitled “Twitter 2.0: From Conversations to Partnerships,” the pair discussed a litany of topics like Musk’s controversial tweets and his idea of “freedom of speech.” Yaccarino asked hard questions, and even though Musk often answered with platitudes like “freedom of speech is not freedom of reach,” Yaccarino kept pressing him.

Multiple sources told Fortune that many people in the industry saw this as her job interview for the CEO gig. “There was chemistry there,” said Paskalis.

The on-stage interaction between the two powerful executives offered hints at how Yaccarino might go about keeping Musk in check at Twitter—something that will be critical not only to her ability to turn Twitter around, but to ensuring that her own reputation doesn’t go up in flames in the process.

“You’ve said you probably shouldn’t tweet after 3 a.m.,” Yaccarino said, alluding to Musk’s middle-of-the-night, and often ill-advised, tweets. “Will you commit to being a little more specific and not tweet after 3 a.m.?,” she pressed him. While Musk didn’t promise to honor the edict, he appeared at ease with the chiding, without the defiance and sarcasm that has sometimes flared up in other recent interviews.

Soon after that conversation, NBCU and Twitter revealed a major renewal of their ad partnership surrounding the Olympics, and speculation quickly mounted about whether or not she was gunning for the chief executive role. Eventually, veteran tech journalist Kara Swisher broke the news styled as an educated guess on Twitter, and Musk confirmed it the next day.

Despite the challenges facing Twitter, multiple sources told Fortune that Yaccarino was made for this role. Advertisers are completely spooked by Musk’s antics, such as defending the “QAnon Shaman” who stormed the US Capitol in 2021, and she might be one of the few people who has what it takes to fix those burnt bridges. Paskalis estimated that it will take Yaccarino “about six months” from her start date to convince advertisers to consider Twitter for their 2024 plans.

“Linda is probably the most highly respected of all of the people on the revenue side of the advertising industry,” he said.

Still, Yaccarino will have to not only convince advertisers to come back to Twitter, but she will have to do it with the wildcard of Musk tinkering in the background. Musk has said he will become Twitter’s chief technology officer, and executive chairman, pushing his “vision” to transform Twitter into a multipurpose app he calls X, while Yaccarino keeps the trains running.

But Musk, the second richest person in the world, is famously impulsive. Shortly after striking a deal to acquire Twitter in 2022, he tried to back out of it, and now acknowledges that he overpaid for the company. His tweets, about everything from trolling PBS and NPR to a photo of his bedside table, featuring two guns and precisely four cans of diet coke, regularly create public relations crises, and even problems with regulators like the SEC.

From NBC glitz to “gutter brawling content”

Yaccarino will be walking into a messy situation at Twitter. Since Musk bought the company for $44 billion in November, more than 75% of the staff has been laid off or quit, and by Musk’s own admission, the value of the company has been cut in half.

And with its disheveled engineers, in-office cots and occasional toilet paper shortages, Twitter’s San Francisco headquarters is a world apart from the glitzy media halls of Manhattan. Yaccarino’s Instagram features a catalog of selfies with celebrities like Kim and Khloe Kardashian, Andy Cohen, Rami Malek, Vin Diesel, several cast members of SNL, the list goes on. “There is not a stage she doesn’t like,” a source close to Yaccarino told Fortune. “So this is a big win for her. And him [Musk]. But it’s not NBC.”

“It’s gutter brawling content. Not prime time streaming pristine content,” the same source added. “So will be interesting how she adjusts to that vibe.”

Despite Yaccarino’s Republican bona fides, some of Musk’s rabid fanbase of supporters have already claimed she’s a “superspreader for the woke mind virus.” Yaccarino chaired the future of work task force for the World Economic Forum, a group of influential political figures and global business leaders that Musk has openly criticized (calling it “boring”), the Washington Post reported. Additionally, as the chair of the Ad Council, Yaccarino collaborated with the Biden White House in 2021 to develop a coronavirus vaccine campaign that prominently featured Pope Francis.

The people who may be rooting for Yaccarino the most may be shareholders at Tesla, the electric car company at which Musk is also the CEO (he’s also leading SpaceX, the space exploration company, Neuralink, a brain computing company, and tunnel-making company The Boring Company).

Shares of Tesla rose 2.1% after the news emerged that Musk had found someone to replace him as Twitter CEO. Wedbush analyst Dan Ives cheered the move in a note to Tesla investors on May 12, describing it as the end of the “Twitter nightmare.”

When it comes to how all this shakes out for Twitter, Paskalis says Disney or NBC would be prime candidates to acquire Twitter, but likely for closer to $8 billion. If Musk wants to see any return on this investment, Paskalis said he’s smart to have chosen Yaccarino to take the helm. Now, Musk’s job is to get out of her way, and let her make money. Whether Musk is able to achieve that remains to be seen.

“I also think he recognizes that he’s been a complete failure at running Twitter. Virtually every decision he’s made has impacted advertisers’ trust in the platform, and they’re 95% of his revenue,” Paskalis said.

“Linda is the last card Elon has left to play,” Paskalis said. “Because if she can’t fix advertising revenue on the platform, then there’s no hope for him ever.”