From left, then-British Prime Minister Theresa May, German Chancellor Angela Merkel, U.S. President Donald Trump, Canadian Prime Minister Justin Trudeau, French President Emmanuel Macron and Japanese Prime Minister Shinzo Abe gather for a photo at the 2018 G-7 summit in Charlevoix, Canada. (Evan Vucci/AP)

Leaders of some of the world’s largest economies will convene in Biarritz, France, on Saturday for the annual Group of Seven summit. The G-7 consists of the United States, France, Germany, the United Kingdom, Italy, Canada and Japan. (Russia got kicked out after it annexed Crimea in 2014).

It’s a meeting that promises awkward handshakes, a “family photo” against a scenic backdrop and tense tête-à-têtes on the sidelines.

On the agenda: trade, international economic rules and climate change — particularly as the Brazilian Amazon burns.

As French President Emmanuel Macron prepares to host this year’s summit, he is endeavoring to ensure that it goes smoothly — particularly after Trump unceremoniously left last year’s meeting in Canada without signing a final joint statement.

Still, the summit — which runs through Monday — will put world leaders’ friendships and antagonisms on stark display. Here are a few key relationships to watch this weekend:

Macron and President Trump

President Trump shakes hands with French President Emmanuel Macron in Normandy, France, in June. (Ludovic Marin/AP)

For a time, President Trump seemed to have a soft spot for 41-year-old French President Emmanuel Macron.

The two men have publicly celebrated the long-standing friendship between France and the United States — and photographers have captured a number of physical exchanges between them that included white-knuckled handshakes and tender embraces.

But the Trump-Macron bromance has proved a tumultuous one. One moment they’re feting each other at a military parade in Paris or a state dinner at the White House. The next, Trump is taking swipes at Macron on Twitter.

Apart from an uncomfortable physical interaction, this weekend’s summit will likely bring renewed conversation about Iran as tensions in the Persian Gulf region simmer. France hopes to preserve the Iran nuclear deal, which Trump pulled the United States out of last year. Macron has sought to position himself as a mediator between the United States and Iran, and he met with Iranian officials ahead of the G-7 to discuss a de-escalation strategy, the Reuters news agency reported.

Macron is also expected to defend his government’s new tech tax, which will hit American companies such as Amazon and Google. (Amazon chief executive Jeff Bezos owns The Washington Post.) Trump threatened to tax French wines earlier this summer in retaliation.

Trump, meanwhile, is likely to float bringing Russia back into the fold next year. CNN reported that Macron expressed openness to the idea in a phone call with Trump this week, though Macron has publicly said the Crimea issue must be resolved before France would welcome Putin back.

German Chancellor Angela Merkel and Trump

German Chancellor Angela Merkel and President Trump pictured during the 2018 G-7 summit in Canada. (Handout/Getty Images)

Merkel has been the target of Trump’s ire perhaps more than any other world leader. A photo of the two staring each other down at last year’s G-7 summit went viral, and their relationship hasn’t improved much since then.

Trump has repeatedly singled out Merkel for what he considers to be Germany’s insufficient contributions to NATO defense spending.

In addition to reiterating calls for higher military spending, Trump is also likely to press Merkel on trade. He has often fixated on the United States’ trade deficit in goods with Germany and the strength of the German economy.

“Germany sells 30 year bonds offering negative yields. Germany competes with the USA,” he wrote in a tweet that took aim Thursday at the U.S. Federal Reserve — another favorite target of Trump’s.

Expect Merkel, who is inching closer to retirement, to counter Trump’s go-it-alone attitude by emphasizing the importance of international cooperation.

Macron, Merkel and British Prime Minister Boris Johnson

From left, British Prime Minister Boris Johnson, German Chancellor Angela Merkel and French President Emmanuel Macron. (LEFT: Jeanne Frank CENTER: Krisztian Bocs RIGHT: Philippe Wojazer/LEF: Bloomberg CENTER: Bloomberg RIGHT: Reuters)

Macron has cast this year’s G-7 summit as a defining moment in his quest to ensure Europe — and multilateralism broadly — survives. Looming over the gathering will be Brexit, which British Prime Minister Boris Johnson has said will occur Oct. 31 with or without a deal with the European Union.

Both Macron and German Chancellor Angela Merkel met with Johnson ahead of the summit. Merkel, who spoke with Johnson in Berlin on Wednesday, suggested they try to reach an agreement on the Irish backstop in the next 30 days, the Associated Press reported.

The backstop, which would tie the U.K. to the E.U. customs union at the Northern Ireland border, has been a point of contention in talks between British and E.U. officials.

Macron, who met with Johnson in Paris on Thursday, called the backstop an “indispensable guarantee” for preserving stability in Ireland and throughout the E.U.

Like Merkel, Macron expressed optimism that reaching an accord before Oct. 31 would be possible. But he stressed to Johnson that any deal should resemble the withdrawal agreement E.U. leaders had already negotiated with Johnson’s predecessor, Theresa May.

Johnson and Trump

Boris Johnson and President Trump pictured in 2017. (Brendan Smialowski/AFP/Getty Images)

Similarities between Donald Trump and Boris Johnson abound, from their mops of blond hair to their penchants for making inflammatory statements.

The G-7 will mark Johnson’s debut on the world stage after the former foreign secretary and ardent Brexit backer took over 10 Downing Street last month.

Trump and Johnson are scheduled to eat breakfast together on Sunday, Bloomberg News reported. The two have already called each other several times since Johnson took office, and Trump told reporters on Tuesday that his British counterpart is “going to do a fantastic job.”

But getting too cozy with Trump would put Johnson in a tricky spot, since many Britons oppose Trump and his policies. Johnson will need to make nice with European leaders as he hammers out Brexit plans — so things could get awkward for Johnson if Trump greets him too warmly.

Japanese Prime Minister Shinzo Abe and Trump

President Trump speaks during a news conference with Japanese Prime Minister Shinzo Abe in Tokyo in May. (Evan Vucci/AP)

Like Macron, Japanese Prime Minister Shinzo Abe has enjoyed a (mostly) amicable relationship with President Trump. Abe and Trump have spoken dozens of times in recent years, and Abe has called their bond “unshakablecb When Trump visited Japan in May, Abe treated Trump to golfing, sumo wrestling tickets and a robatayaki meal.

That doesn’t mean there aren’t points of tension. Trump has downplayed the significance of North Korean missile tests that have sparked concern in Japan. He has disparaged the Trans-Pacific Partnership, an Obama-era trade deal that included Japan. And he has threatened to levy 25 percent tariffs on Japan’s auto industry.

Japanese Economy Minister Toshimitsu Motegi and U.S. Trade Representative Robert Lighthizer met in Washington this week to discuss trade ahead of a conversation between Trump and Abe at the G-7, Reuters reported. Trump apparently hopes to announce a trade deal at the summit.

Italian Prime Minister Giuseppe Conte and Macron

Italian Prime Minister Giuseppe Conte and French President Emmanuel Macron. (LEFT: Stefan Wermuth RIGHT: Gonzalo Fuentes/LEFT: Bloomberg RIGHT: Reuters)

It’s an awkward time for Italian Prime Minister Giuseppe Conte to be rubbing shoulders with other world leaders. He’s making an abrupt exit from Italy’s most powerful post after his own interior minister, the far-right Matteo Salvini, brought his populist coalition crashing down.

Still, Conte’s interactions with Macron are worth watching. Relations between Italy and France have been unusually strained in recent years, as they tussled over a high-speed rail link and Mediterranean migration. At one point, they soured so much that France briefly recalled its ambassador from Rome.

Macron and Conte have usually managed to patch up their differences — and now they may find a common foe in Salvini, who has praised the French Yellow Vest movement challenging Macron.

Will his lame-duck status embolden Conte to speak out against Salvini at the G-7? It’s certainly a possibility. Meanwhile, expect other heads of state to snub the Italian leader; Conte is the only leader with whom Trump has not scheduled a one-on-one meeting, for instance.

Canadian Prime Minister Justin Trudeau and Trump

President Trump talks to reporters during a meeting with Canadian Prime Minister Justin Trudeau in the Oval Office on June 20, 2019, in Washington. (Evan Vucci/AP)

Trump and his younger counterpart to the North have had a somewhat fraught — and at times, bizarre — relationship.

Justin Trudeau, Canada’s 47-year old Liberal Party leader, has been described as the “anti-Trump,” and Trump blasted him as “weak” and “dishonest” in a Twitter firestorm after the last G-7 summit. The two have apparently exchanged digs via snail mail, as well, Vanity Fair reported.

Trudeau is facing a tough battle at home ahead of Canada’s elections in October — particularly after he was recently called out by a Canadian ethics watchdog for violating ethics laws. The G-7 may give him an opportunity to bolster his image as an antidote to Trump on the world stage.

He’s also expected to meet with Johnson to discuss trade during the summit, CBC Radio Canada reported.