Prince Harry and Meghan Markle welcomed Archie Mountbatten-Windsor into the world on May 6, 2019 - but even the birth of their first child caused controversy.
The Duchess of Sussex reportedly gave birth to the sprog eight hours before Buckingham Palace even announced she had gone into labour, marking a decided move away from the norm.
Most royal births, including those of Princes William and Harry, were announced shortly after the mother was admitted to hospital, and the Prince of Wales was supposedly livid at the decision to keep the birth under wraps.
READ MORE: Royal fans demand King Charles 'strip Harry and Meghan of titles' after Netflix trailer
Royal author and historian Robert Lacey wrote in the Daily Mail: "According to one of my sources, it's been pointed to him that everyone has a difficult sister-in-law.
"William's response was to nod his head in sage acceptance.
"Then suddenly he broke out angrily. 'But look at the way that bl***y woman treated my staff - merciless!'"
William was reportedly "not impressed" at the Sussexes' efforts to keep Archie's birth a secret for several hours before revealing the information to the Palace.
"William did not think too highly of Harry and Meghan’s 'prima donna' manoeuvres to conceal the birth of their son in May 2019," Lacey added.
"This impression was confirmed by the failure of William and Kate to visit the new arrival for a full eight days."
In the book The New Royals, author Katie Nicholl wrote the Sussexes wanted a private moment as a new family before announcing Archie's birth.
"One source described Harry as being 'almost morbidly obsessed' with keeping Archie's birth as secret as possible, breaching the unwritten contract between the royals and public," Nicholl claimed.
"Harry and Meghan had wanted some time as a new family before they presented their son Archie to the world."
Archie's birth is part of a long history of conflict between Prince William and Prince Harry.
Friends of the pair had reportedly hoped the brothers would reconcile after Prince Philip's funeral in April 2021, Lacey wrote - but sadly it was not to be.
"In April, the sad news of Prince Philip's death seemed to offer a glimmer of hope," Lacey wrote.
"The family gathering for their grandfather's funeral would bring the warring brothers together in an atmosphere of reflection.
For the latest breaking news from the Royal Family and stories from the Daily Star, sign up for our newsletter by clicking here.
"But those hopes were dashed within minutes of the siblings getting inside the castle and beyond camera vision. They started quarrelling again.
"'There they were, at each other's throats as fiercely as ever,' relates one long-time friend with a tired and helpless shrug.
"'The rage and anger between those two has grown so incredibly deep. Too many harsh and wounding things have been said.'"
And while the brothers each have their own supporters, even those in the Sussex camp have admitted Meghan may have ruffled some royal feathers.
"Sussex supporters have noted the bizarre combination of self-promotion and self-pity that characterises Meghan, and can see why it has infuriated William," Lacey wrote.
"'Meghan can be a 500% nightmare,' some close friends of Harry are among the first to admit.
"'The never-ending PR. She's just so . . . American!'"
READ MORE: