All of a sudden one of the world’s “pariah” leaders, the Saudi crown prince, Mohammad bin Salman, is welcome everywhere — including in Turkey, the scene of the crime that made him infamous. Can President Biden be far behind?

Prince Mohammad, long shunned for his role in the murder of an American resident, Jamal Khashoggi, was at Ankara today, kissing and hugging Prime Minister Erdogan. The warm reception for MbS, as the crown prince is known, contrasts with a half-decade of chill between the two countries. 

How? “It’s like that movie ‘Trading Places,’” a Mideast watcher at the Foundation for the Defense of Democracy, Jonathan Schanzer, says. In the 1983 comedy, a successful investor, played by Dan Aykroyd, is forced to switch roles with a street bum, Eddie Murphy, as two cynical billionaires try to prove how easily societal roles can be altered. 

After the murder of Khashoggi, Prince Mohammad was shunned by everyone. Mr. Erdogan was a major catalyst in the Saudi humiliation, slowly releasing painful footage and audio recordings from the Saudi consulate at Istanbul, where a group of Saudi operatives killed Khashoggi and dismembered his body.

Washington couldn’t get enough of the details that for weeks emerged from Ankara. Mr. Erdogan’s own human rights transgressions were overlooked, while the de facto Saudi ruler became a symbol of all that’s evil in Mideast tyranny. 

As if the two billionaires in “Trading Places” are making their little bet in the Mideast, fortunes have now turned. Mr. Erdogan presides over Turkey’s worst economy in memory. The lira has lost its value and inflation is at 70 percent. Meanwhile, as crude oil fetches $110 a barrel, the highest price since 2008, Saudi Arabia is being wooed by regional and world leaders. 

No matter how he tries to couch it, Mr. Biden’s mid-July trip to Riyadh is widely seen as a humiliating reversal of relations with Prince Mohammad, whom he once vowed to make a world pariah. It’s Mr. Erdogan who is now seeking favors from MbS, too.

When Turkey used the killing of Khashoggi to humiliate the Saudis, Riyadh shunned Turkish economic ties. Last year Turkish companies exported $200 million in goods to Saudi Arabia, down from around $3.2 billion in 2019.

As Mr. Erdogan suffers the worst economic misfortunes of his presidency with next year’s election approaching, he has little choice other than to beg the Saudis to renew trade, tourism, and additional ties. He is trying to repair relations with others in the region as well, including Israel, which until recently he had called a “criminal state.” 

Prince Mohammad’s Ankara visit is the last stop in a Mideast swing that took him to Egypt and Jordan in search of a strong coalition of Arab countries to counter Iran’s growing influence in parts of the region.

Blessing that budding coalition, and possibly adding Saudi Arabia to a circle of Arab countries that have formalized relations with Israel, was meant to highlight Mr. Biden’s trip next month. Some expect him to spin it as his own diplomatic achievement, following a string of foreign policy blunders. 

Yet, like Mr. Erdogan, Mr. Biden wants his newfound friendship with the desert kingdom to benefit America economically as well. With the Saudis likely to raise oil drilling quotas, prices at the pump would then, hopefully, be lowered. The effect on the Consumer Price Index would be harder to predict.

While political opponents sneer at Mr. Biden for appearing to forget the murder of Khashoggi and overlooking other Saudi sins, the president nevertheless seems to be realizing the time has come to drop the pretense of basing his foreign policy on human rights. Selectivity doesn’t work with such a strategy. Mr. Biden might, though, find that in reality Saudi Arabia is far from the Washington caricature of the world’s worst rights violator.

A conservative Sunni country leaning on harsh laws for decades, Riyadh has in fact made some improvements since the rise of Prince Mohammad, including by promoting basic rights for women. It was the murder of Khashoggi, a Washington Post columnist, that had pushed MbS out of favor, especially in Democratic Party circles.

Many in Riyadh still see Turkey as a top instigator in the Khashoggi affair. Mr. Erdogan has also raised Saudi ire by hosting various extremist Sunni factions considered enemies of the kingdom. Additionally, Egypt and other Arab regimes are angry with Turkey for its alliance with the Muslim Brotherhood, Hamas, and even some Islamist Shiite groups.

Mr. Erdogan now promises to sever ties with the Islamist extremists, which may prove difficult. A top Hamas official who has found a home in Turkey for years, Saleh Arouri, has been officially shunned. Yet, he keeps going in and out of the country unmolested. 

So how long can the Saudi-Turkish rapprochement last? “I think MbS will never forget what Erdogan did” in the Khashoggi affair or in his alliance with the Brotherhood, Mr. Schanzer says

After trading places, Mr. Erdogan and Prince Mohammad are, for now, friends. Mr. Biden, who until recently was riding a high human-rights horse, is next in line to kiss MbS’s ring.