Heraldo de Madrid - William and Harry: Britain's warring royal brothers

The pair -- dubbed "the heir and the spare" from an early age -- have failed to put aside their differences, despite their father King Charles III's cancer diagnosis.

And as Prince Harry, the Duke of Sussex, prepares to return to the UK in the coming weeks with his wife, Meghan, and two young children, all eyes will be on whether the brothers are able to repair ties.

Diana had made her two cherished boys promise to always stand by one other, but almost 30 years after her death they are no longer talking.

The last time they were seen together was in September 2022 at the death of their grandmother Queen Elizabeth II.

Even Charles's February 2024 announcement that he was receiving treatment for cancer did not spur a reconciliation between Prince William, 44, and his younger sibling Harry, 41.

With William in the UK and Harry self-exiled in California, the gulf between the two has only widened.

A visibly upset Harry said in an emotional February 2025 BBC interview that he missed the UK, and he wanted to reconcile with his family.

He and Meghan and their two children Archie 7, and Lilibet, 5, did meet privately with Charles and Queen Camilla in July. It was the first time the children had been with their grandfather since 2022.

But Harry has admitted the revelations made in his 2023 controversial biography "Spare" and a devastating TV interview with Oprah Winfrey had rocked relations.

"Of course some members of my family will never forgive me for writing a book," he told the BBC. He added, however: "I would love for reconciliation."

Royal expert Richard Fitzwilliams told AFP he believed William would be "very unhappy" about the news of Harry's return.

"I think William would be adamantly opposed to this. Because there is a very deep rift," he said.

"He feels Harry has betrayed him. He's made that clear."

- 'Different paths' -

In 1997, the nation's hearts went out to the two young boys, then aged 15 and 12, as they accompanied Diana's coffin through hushed London streets at her funeral.

Since then, every twist of their relationship has been chronicled by the press.

From a young age, William was depicted as the charming, steady heir to the throne, with Harry the wayward but loveably roguish sibling.

When William met his future wife Kate Middleton at university, Harry described her as "the sister I've never had and always wanted".

The trio were often seen together but when a besotted Harry introduced his new girlfriend, Meghan Markle, to William in 2016, the reaction was frosty, he recounted in "Spare".

William had advised him not to rush the relationship with the divorced American former television actress three years his senior, Harry said.

After Harry and Meghan married in 2018, the two couples were first described in the press as the "Fab Four".

But Harry accused William of not doing enough to help Meghan adapt to life in the royal family.

The press delighted in the rivalries between the brothers, playing the sophisticated, beloved Kate off against Meghan, depicted as a capricious outsider.

- 'Arch nemesis' -

In late 2019, the cracks were visible, with Harry admitting in a television interview that he and his brother were on "different paths".

By early 2020, Harry and Meghan -- formally known as the Duke and Duchess of Sussex -- had had enough. They quit royal life, moving eventually to the United States.

The couple's explosive interview with US chat show queen Winfrey in March 2021, just added more accusations from Harry and Meghan against the royal family, including that of racism, as well as a scathing line that William only chose Kate because she fitted the mould of a royal wife.

In Harry's autobiography, "Spare" he went even further, portraying his brother as prone to anger and having once knocked him to the ground during an argument about Meghan.

"I was the shadow, the support," he wrote. "I was brought into the world in case something happened to Willy."

William, Harry said, was his "beloved brother" but also his "arch-nemesis".

"It's in the interest of both King Charles and Prince William to reconcile with Harry," said royal historian Ed Owens.

Once William accedes to the throne and becomes head of the Church of England it will be his Christian duty "to forgive his brother".

"I expect it will take some time," Owens said. But he added: William "will look benevolent. He will look like he is exercising magnanimity."

A.Montoya--HdM