Given their tumultuous history, Las Vegas casino titan Steve Wynn would seem an unlikely inaugural party planner for President-elect Donald Trump.

Wynn, now a finance vice chair of Trump’s inaugural committee, once had nothing kind to say about his longtime gaming industry nemesis.

“He’s an incompetent... all hat, no cattle,” Wynn told a reporter for The Wall Street Journal in 1996.

Trump, meanwhile, was known for calling Wynn an “underachiever” and much worse.

But those were Hallmark sentiments compared to the allegations leveled in a 1999 litigation filed by Wynn’s Mirage Resorts against Trump Hotel & Casino Resorts Inc. Before reaching a confidential settlement in February 2000, court documents revealed representatives of Wynn and Trump engaged in a nasty behind-the-scenes battle that generated allegations of fraud, money-laundering, perjury, conspiracy, and the theft of trade secrets. Private investigators dug for dirt, and at one point a Trump detective turned “double agent” on behalf of Mirage’s lawyers, according to a Trump filing that accused his own agent of capturing private conversations with recorders secreted in briefcases and even a jock strap.

As the head of Mirage Resorts at the time of its 1999 suit, Wynn called the affair “the most outrageous misconduct, the most flagrant violations of law and decent behavior in the history of the resort hotel industry.”

Trouble was, Wynn’s offense was quickly subsumed by Trumps ferocious defense. According to court documents filed on behalf of Trump Hotels and several other defendants, a Mirage senior vice president ran an “undercover operation” that included recruiting and co-opting Trump organization investigator Louis “Curt” Rodriguez “through a series of illegal, unethical, and intimidating acts designed to induce a breach of his fiduciary duty” to his employer. A Mirage executive “directed Rodriguez’s unlawful and unethical activities,” information contained in Trump’s list of proposed witnesses stated.

Among the dirt Rodriguez traded while back-dooring information to Wynn’s camp: “While working for (Trump), Rodriguez learns that Mirage is the subject of an ongoing FBI and United States Customs criminal investigation into money-laundering violations,” a Trump document alleged.

It got worse. Trump’s defense team alleged that Rodriguez planted false information with the FBI, had surreptitiously taped a Las Vegas FBI supervisor, learned of a federal money laundering investigation into Mirage and collected information deemed useful in antitrust litigation involving Mirage’s thwarted 1995 attempt, opposed by Trump and others, to return to Atlantic City and build a billion-dollar casino resort in its marina district.

On a personal note, the Las Vegas case was additionally intriguing because Wynn’s camp was accused of suborning perjury to establish jurisdiction in Kentucky in a defamation lawsuit the casino king had filed against me over an investigative biography published in 1995. As the Wynn-Trump litigation heated up, the Kentucky lawsuit was dismissed.

With allegations of political fixing rampant and Wynn’s project foundering under the weight of delay, Mirage filed a federal antitrust suit in New York that alleged Trump and Hilton Hotels had been manipulating the process to prevent a Mirage entry into the market. (Given Atlantic City’s current level of dilapidation, that may have turned out to be a blessing in disguise.) Wynn’s side followed with the 1999 lawsuit in Las Vegas that led to the embarrassing Spy vs. Spy accusations.

Then, silence. A settlement.

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Trump and Wynn are a lot alike, including that both hate to be compared to anyone else. Both had graduated from the University of Pennsylvania. Trump was a silver spoon scion of a New York real-estate developer. Wynn was raised in the gambling racket, the son of a bingo king, but quickly rose to stardom as a casino phenom in Las Vegas.

For every generous remark they made about each other, there were a dozen daggers. “They hate each other’s guts,” longtime casino analyst Marvin Roffman told Philadelphia reporter George Anastasia in 2000. “It’s like poison.”

Wynn entered Atlantic City in style with the 1979 construction of the Golden Nugget, which dominated the market through the early 1980s. His departure from the Boardwalk in 1987 with a $440 million sale to Bally proved prescient. Not long afterward, Atlantic City began to slip and Wynn was making headlines as the creative force behind The Mirage and other mega-resorts.

Trump, meanwhile, unsuccessfully sued to block the sale of Bally to Wynn and increasingly talked about entering the Las Vegas casino market. At one point, he gave press interviews during a stay at Wynn’s Golden Nugget. But despite more talk about challenging the titans of the Strip, Trump remained in New Jersey and in March 1990 added his third Atlantic City casino.

Trump did, however, manage to lure away casino executive and former gaming regulator Dennis Gomes from Wynn’s company to work at the Taj Mahal. The move generated a nasty breach of contract litigation. Gomes eventually settled in 1994, but not before he painted a picture of Wynn as a volatile tyrant capable of abusing everything from corporate assets to cocktail waitresses.

But Wynn also built winning casino resorts. Trump spent the 1990s perfecting the art of the well-timed corporate bankruptcy reorganization—four times in the decade, according to Politifact. (And then twice more after the turn of the century.)

Trump’s propensity for running into bankruptcy gave rise to one of Hillary Clinton’s best campaign moments. In a speech, she observed, “He’s written a lot of books about business. They all seem to end at Chapter 11.”

Wynn sold Mirage Resorts to MGM Grand in 2000, then spent the decade building Wynn Resorts into a casino industry colossus in large part on the strength of its lucrative Macau operations. Trump’s casino ventures crumbled at their financial foundations, but he embraced the salesman’s role by branding his name far and wide to gaudy profit, a celebrity profile, and now the ultimate spotlight.

A funny thing happened when Trump joined the Republican presidential circus much to the entertainment of late-night talk show hosts. Wynn was among few corporate executives to state publicly that Trump had a strong business sense and a chance to win in a crowded field. Wynn also attended a victory celebration when Trump pulled off an upset in the Nevada Republican primary.

Although he declined to officially endorse Trump as fellow gaming goliath Sheldon Adelson had done, Wynn’s early warmth for the candidate stunned those of us who have followed the blood trail of their relationship over the past 30 years.

If Wynn—who now says he never committed to booking “specific performers” for his old enemy’s big party—could only persuade Garth Brooks or some of his other many friends from the entertainment world to perform or even just show their faces at the inaugural ball, he’d surely be President Trump’s best friend forever.