Prince Harry's upcoming memoir "Spare" has everyone wondering what the highlight of his most-awaited book will be.

Many speculated that the book will be full of accusations against the Duke of Sussex's father, King Charles. However, one insider claimed that it was not the case.

The book will reportedly discuss the trauma of the death of his mother, Princess Diana, and sharp criticisms of his brother Prince William and Kate Middleton.

The insider noted that William and Kate will get a lot sharper scrutiny than they expected.

The same source added that the book will be "worse for them than the royal family is expecting," with details laid bare and the king "coming out of it better" than projected.

Prince Harry's memoir "Spare" will be released on January 10 by Penguin Random House.

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Prince Harry Memoir 'Spare'

New claims reported that after Harry's upcoming memoir was leaked to the press, warnings were issued to the royal family.

The insiders noted "minute details" and descriptions of the fight between Harry and William.

The same source noted that they cannot see how Harry and William will be able to reconcile once the memoir is released.

The book's publication will be with two major broadcast interviews, one in the United Kingdom for ITV by Tom Bradby.

Anderson Cooper will also interview Harry for CBS' 60 Minutes. The two interviews are expected to be released on January 8.

Meanwhile, there have been reports that Harry's wife, Meghan Markle, is reportedly planning her own.

One source noted that Markle plans to write a book and leave no stone unturned.

The source went on to say that there is a feeling that there is little to lose and "may as well go ahead."

The insider said that the process "is already quietly underway."

Prince Harry and Prince William's Relationship

Reports of a rift between the two brothers made headlines in 2018 after the Sussexes chose to move away from Nottingham Cottage in London to Frogmore Cottage in Windsor in England.

One source noted that the brothers had grown apart over the years.

The same source said in October 2019 that William still cares about his younger brother and hopes that Harry will open up to him about his current struggles.

In November 2019, it was reported that things between the two brothers were "not great."

In January 2020, Harry and Markle decided to step back from their senior royal duties, which was then made permanent in February 2021.

Recently, the Prince and Princess of Wales went to Boston for a short trip in the United States. However, the two did not make any plans to see Harry and Markle.

The Netflix docuseries of the Sussexes aired last December, which featured claims against the royal family and the treatment they received while they were part of the monarchy.

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Written by: Mary Webber

WATCH: Royals braced for more revelations in Prince Harry memoir - from Sky News