What is the best movie sequel of all time? In the world of science fiction, there are three contenders for that title: The Empire Strikes Back, Aliens, or Terminator 2: Judgment Day.

All three feature main characters from the first film facing new challenges and getting some character development – whether it is Luke Skywalker learning Darth Vader is his father after training with the Jedi Master Yoda, Ellen Ripley rescuing a little girl from the Xenomorph queen, or Arnold Schwarzenegger becoming a “good” Terminator while Sarah Connor fought hard to save her son.

One of the biggest blockbusters for U.S. Catholics is now getting its own sequel: Donald Trump is inaugurated president in Washington, D.C., while Pope Francis holds sway at the Vatican.

The first chapter of Francis vs. Trump was one of the biggest shows since the United States began diplomatic relations with the Holy See in 1984, and the main characters’ tempestuous relationship began even before the former reality TV star was elected in 2016.

In February of that year, Francis was asked about Trump proposing a border wall between the United States and Mexico.

“Building walls instead of bridges is not Christian; this is not in the Gospel,” the pope said. “I’d just say that this man is not Christian if he said it this way.” The then-candidate for the Republican nomination said it was “disgraceful” for a religious leader to question another person’s faith.

RELATED: Pope Francis, Trump meet in ‘Odd Couple’ encounter

When Trump was later elected, observers could sense the tension when the two men first met at the Vatican the next year, although they also noted they seemed to be getting along after their meeting.

Still, John L. Allen Jr. – the owner and editor of Crux – noted at the time there were a lot of similarities between the two leaders, although admitting they were “wildly different men” in their backgrounds, agendas, and views of people.

“First, both were considered implausible long-shots prior to coming to power, but both defied the odds,” he wrote in 2017 to point out these similarities.

“Both, too, ran as anti-establishment figures promising to shake up entrenched ways of doing business,” Allen added.

RELATED: Despite it all, Francis and Trump may just hit it off

“Both Trump and Francis have also discovered that constantly taking potshots at the bureaucracies you’re trying to lead is a tricky business, a bit like trying to change horses mid-stream, and both have run into a degree of internal resistance with which they’re still struggling to cope,” the head of Crux said.

“Both Trump and Francis are populists, seeing their legitimacy as coming from the people rather than elites, and both take a certain pride in the fact that elites tend to view them with alarm – in Trump’s case, that’s the media establishment and the liberal intelligentsia, while for Francis it’s theologians, canonists, and liturgists, especially those attached to the fine points of the law,” he added.

“In Catholic circles at the moment, many conservative Catholics spend their days waiting for the next papal outrage upon which to pounce, competing with one another on social media to see who can provide the snarkiest bit of commentary. More liberal Catholics, on the other hand, have so thoroughly drunk the Kool-Aid that any criticism of Francis whatsoever automatically qualifies the critic as a member of a ‘vast right-wing conspiracy’ to subvert the pontiff. Likewise with Trump, admitting any virtue at all to his administration is considered material cooperation in evil by most American liberals, while spotting any vice is anathema to Trump’s supporters (and, it must be said, often to Trump himself),” Allen said in 2017.

“To say the least, both Trump and Francis are captivating public personalities, and whether you like them or not, you just can’t look away,” he said.

Like all good sequels, this one honors the first episode, but adds to it.

Neither man was a spring chicken in 2016 – Pope Francis was 80 and Trump was 70 – and are now both the better part of a decade older.

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They are also both facing more scandals. The Holy Father has been continually hit with new clerical abuse stories hurting his legacy, while Trump was sentenced to felony charges (with unconditional discharge) in New York shortly before taking office.

Although they will still disagree on migrants and asylum seekers – Pope Francis just on Sunday evening said it would be a “disgrace” for Trump to conduct promised mass deportations of undocumented persons – both men support a peace process in Ukraine involving “dialogue” – which many observers say can only favor Russia.

In addition, although the People’s Republic of China is troubled by the new U.S. president’s desire to implement new tariffs, they are pleased by the fact he has announced he will delay a ban on the Chinese social media platform TikTok and wants to visit the Asian giant early in his presidency. This seeming goodwill towards the Communist government echoes the strategy of the current pontiff in its dealing with China, where he has renewed a deal on the appointment of bishops which critics says doesn’t help stop the persecution of Christians in the atheist country.

They also both face problems of their successor. Trump can’t run for reelection, and the U.S. presidential candidates usually begin informally running a few years before the election. The cardinals around the world are also informally discussing who they would like to see succeeding the elderly Francis.

Both men know their time is probably short, and both still feel they have much to do.

When they have their first encounter – the date hasn’t yet been determined – these story points will play prominently in the sequel to Francis vs. Trump. It could end up being another blockbuster.

Follow Charles Collins on X: @CharlesinRome