Inside Prince Harry, Prince William's royal reunion: Behind the scenes of dramatic appearance with their wives

Prince Harry and Prince William shocked the world when they appeared together with their wives for the first time since 2020.

Prince Harry, Meghan Markle, Prince William and Kate Middleton, sometimes referred to as the "Fab Four," made their way outside of Windsor Castle on Sept. 10 to view floral tributes left for Queen Elizabeth II in the wake of her death on Sept. 8.

However, the special occasion was marred by reports that Prince Harry and Markle delayed the reunion.

"Yes, of course they were an hour late, it was because Prince William was told by his father, the now King Charles, to extend the invitation because they found out Meghan Markle had her U.S. PR firm book an ‘alternate’ walkabout, which was headed off. So, it was a last-minute invitation to head that off, she was breaking protocol (yet again)," royal watcher Hilary Fordwich told Fox News Digital.

A representative for Markle did not provide comment when reached by Fox News Digital.

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Fordwich explained that Prince Harry and Markle likely had to "scramble" to be ready for the public moment, and though she could not confirm, she noted that the Duchess of Sussex normally does have her hair and makeup team handy.

"It was a last-minute invitation, so, yes, they had to scramble to get ready, they weren't in mourning clothes."

"The Prince of Wales's olive branch led to a 45-minute negotiation before the 'Fab Four' were reunited … also Prince William was rather dismayed by some coverage focusing on Harry and Meghan’s movements the day Queen Elizabeth II died rather than the magnitude of mourning," Fordwich added. "So, he then was resolved to make contact with Harry and Meghan."

The 45-minute negotiation was likely due to Prince Harry's plea for proper security. The Duke of Sussex is currently in a legal battle with the government of the United Kingdom as he fights for security following his decision to step back from his senior role as a royal.

"If we see any more of Harry and Meghan over the next few days, apart from Monday's service, we won't receive word of the appearance until the very last minute," royal expert Kinsey Schofield told Fox News Digital.

"That is how they are operating while in the U.K. Prince Harry is currently in a legal battle with the government over his security, and it is my understanding that the 'negotiations' that took place prior to Saturday's joint appearance were security related. Harry is still fearful for the safety of his family, but I do believe we will see more of them."

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Royal author Christopher Andersen, who wrote "Brothers and Wives: Inside the Private Lives of William, Kate, Harry, and Meghan," noted to Fox News Digital that Queen Elizabeth II's death has likely brought Prince William and Prince Harry together as they honor her.

"William and Harry have come together for this one moment in history to honor the grandmother they both loved, just as they briefly came together for Prince Philip's funeral and the unveiling of the Kensington Palace statue honoring their mother last year," he said. "But it remains to be seen whether they go back to their separate corners as soon as the funeral is over."

The royal author also spoke to Fox News Digital about Prince William's title change and how that could affect his relationship with Prince Harry.

"Harry knew this moment was coming," Andersen said. "That's why he and Meghan struck out on their own to create a life for themselves far from the gravitational pull of the monarchy."

"As much as Harry loves his brother, he has always struggled to some extent in William's shadow," he added. "Harry is happy that William and Kate are so willing and so prepared to take on the heavy burden of being Prince and Princess of Wales. But if the Sussexes felt eclipsed by the Cambridges, one can only imagine how they feel now."

Andersen emphasized that the royal family is "on their best behavior" in an effort not to embarrass the family name in the wake of Queen Elizabeth II's death.

"William and Harry used to laugh and joke around pretty much every time they got together. That playful brotherly bantering that was the hallmark of their relationship is not much in evidence now," he told Fox News Digital. "They are civil enough to one another, but that's about it. Everyone is on their best behavior for the moment, careful not to do anything that would have embarrassed or upset their grandmother."

King Charles III seemed to extend his own olive branch to Prince Harry by mentioning his son and Markle in his first address after taking the throne. However, it's unclear if any other steps will be taken to mend the father and son's relationship.

"Charles has extended an olive branch to Harry and Meghan by mentioning them in his accession speech, but it's hard to imagine that much will come from it," Andersen said. "The palace is holding its collective breath, waiting to see what new bombshells are contained in Harry's forthcoming tell-all memoir."

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Harry announced he was writing a tell-all memoir in 2021 and reportedly did not inform Charles before the news broke.

"I’m writing this not as the prince I was born but as the man I have become. I’ve worn many hats over the years, both literally and figuratively, and my hope is that in telling my story—the highs and lows, the mistakes, the lessons learned—I can help show that no matter where we come from, we have more in common than we think," he said in a press release at the time.

"I’m deeply grateful for the opportunity to share what I’ve learned over the course of my life so far and excited for people to read a firsthand account of my life that’s accurate and wholly truthful."