President Trump listens during a news conference with Canadian Prime Minister Justin Trudeau in the East Room of the White House on Monday. (Jabin Botsford/The Washington Post)

As President Trump stood on the world stage with Canadian Prime Minister Justin Trudeau on Monday afternoon, he carefully read from a script in a binder, adding emphasis to words here and there but refraining from using his hands to do the same.

“Prime Minister Trudeau, on behalf of all Americans, I thank you for being with us today,” Trump said flatly, without looking at his fellow world leader. “It is my honor to host such a great friend, neighbor and ally at the White House — A. Very. Special. Place.”

Trump had arrived at the lectern with a frown and remained deeply serious as he described the relationship between the two countries, alluding to tension points but not going there as he might at a campaign rally. As Trudeau took his turn speaking, Trump stood stoically, gazing out at the reporters assembled in the White House’s lavish East Room. He did not fidget quite as much as usual.

For a man who has long been fascinated by celebrities, the opportunity to share a stage with another world leader is the ultimate reminder of just how far he has unexpectedly come. His demeanor is remarkably different in these moments. It appears as though he has been cast by a Hollywood director to play the very serious role of President of the United States.

The country first got a glimpse of this version of Trump in late August when, amid upheaval in his presidential campaign, the businessman traveled to Mexico City for a hastily organized meeting with Mexican President Enrique Peña Nieto.

Japanese Prime Minister Shinzo Abe is greeted by President Trump on his arrival at the White House Friday. (Melina Mara/The Washington Post)

Trump built his campaign on attacks on Mexico, accusing the government of sending dangerous criminals into the United States illegally and promising to build a massive wall along the southern border. But at a news conference with Peña Nieto, Trump was quietly deferential, solemnly listening to remarks through a translator and then offering a diplomatic message of his own — without mentioning rapists, making Mexico pay for the wall or any of the other things that were key to his campaign messaging.

Trump instead focused on the history of the “close and honest relationship” between the two countries and the potential for “working beautifully together,” with broad mentions of commerce, trade, religion, security and quality of life in the two countries. On immigration policy, Trump struck a softer tone as he focused on the humanitarian crises created by illegal border crossings and drug cartels. As he read from a script, Trump’s vocabulary became more varied and his sentences more complex.

“A strong, prosperous and vibrant Mexico is in the best interest of the United States and will keep and help keep — for a long, long period of time — America together. Both of our countries will work together for mutual good, and most importantly for the mutual good of our people,” Trump said at the time. “Mr. President, I want to thank you. It’s been a tremendous honor, and I call you a friend. Thank you.”

The political chattering class marveled at the pivot in tone it thought that it had just witnessed. But hours later, Trump got into a Twitter fight about the wall with Peña Nieto, then delivered an impassioned speech about immigration at a campaign rally in Arizona. Even though he again read from scripted remarks, his usual, brash style was back — lashing out at the media, threatening to deport millions of undocumented immigrants and telling the stories of Americans killed by immigrants.

At one point, he declared: “We’re like the big bully that keeps getting beat up.”

President Trump holds a joint news conference with British Prime Minister Theresa May on Jan. 27. (Melina Mara/The Washington Post)

Since becoming president last month, Trump has entertained British Prime Minister Theresa May in late January, Japanese Prime Minister Shinzo Abe late last week and Trudeau on Monday. Israeli Prime Minister Benjamin Netanyahu is expected on Wednesday.

With each visit, the president has continued to play the role and has focused on relationship-building that appears to be based more on personality than geopolitics. He seemed to hint that at any moment, this act could end — publicly submitting world leaders to the same treatment given to political rivals, dissenting Republicans, reporters, federal judges and anyone who gets in his way.

“We have a very, very good bond, very, very good chemistry,” Trump said during Abe’s visit. “I’ll let you know if it changes, but I don’t think it will.”

Peña Nieto canceled a scheduled visit to Washington in late January as Trump continued to insist that Mexico would pay for the border wall. At a joint news conference with the United Kingdom’s May, a reporter asked Trump about his relationship with the Mexican leader.

“I have great respect for Mexico,” Trump said. “I love the Mexican people. I work with the Mexican people all the time. Great relationships.”

He added: “I think a very good relationship, the president and I. And we had a talk that lasted for about an hour this morning. And we are going to be working on a fair relationship and a new relationship.”

At the same news conference, a British journalist asked Trump about his praise of Russia — prompting Trump to joke that the question might sour his relationship with May.

“[President Vladimir] Putin and Russia — I don’t say good, bad or indifferent. I don’t know the gentleman,” Trump said. “I hope we have a fantastic relationship. That’s possible, and it’s also possible that we won’t. We will see what happens.”

Monday’s news conference with Trudeau was different because the prime minister flawlessly switched between French and English, composing long, warm sentences in both languages. Trump repeatedly put in and took out earpieces to hear a translation, but finally just flung them onto the lectern with a flick of personality that had been missing up until that moment.

In answering a final question from reporters, Trudeau — a progressive in his 40s — compared himself to the 70-year-old Republican president.

“Both President Trump and I got elected on commitments to support the middle class, to work hard for people who need a real shot at success,” the Canadian leader said.

Trump agreed but also one-upped Trudeau by name-dropping car manufacturers that have pledged to create more jobs and Chinese business magnate Jack Ma.

“I think it’s going to be a very exciting period of time for the United States and for the workers of the United States because they have been, truly, the forgotten man and forgotten women,” Trump said, thrusting a finger into the air and prompting a clattering of cameras that had been waiting for the president to do something besides scowl. “It’s not going to be forgotten anymore, believe me. So, our relationship with Canada is outstanding. And we’re going to work together to make it even better.”

Trump then thanked the crowd and quickly left the stage.