Prince William & Kate Middleton's Son George Cheekily Told Classmates 'My Father Will Be King So You Better Watch Out': Book

Knowing whose boss. Despite only being nine years old, it seems Prince George knows exactly what family he belongs to — and wants to make sure his peers know too.

According to royal author Katie Nicholl, Prince William and Kate Middleton's eldest son told his schoolmates that they better be careful because his dad will one day be Head of state.

"George understands he will one day be king and as a little boy sparred with friends at school, outdoing his peers with the killer line: 'My dad will be king so you better watch out,'" Katie claimed in her bombshell royal book, "The New Royals."

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Despite using his cheeky comeback for a classmate who crossed him, George, to some degree, understands the importance of his duty within the royal family.

The royal expert claimed the Prince and Princess of Wales, who were given their new royal titles following the death of Queen Elizabeth II, have been raising their three children with an understanding of the monarchy. William and Kate, both 40, share Prince George, Princess Charlotte, 7, and Prince Louis, 4.

"They are raising their children, particularly Prince George, with an awareness of who he is and the role he will inherit, but they are keen not to weigh them down with a sense of duty," Katie claimed in her book.

King Charles III's eldest and his daughter-in-law reportedly only told George of his role as the future King two years ago.

In a new chapter of royal author Robert Lacey's book, "Battle of Brothers: William, Harry and the Inside Story of a Family in Turmoil," which was updated last year, he claimed the couple told George about his future role "sometime around his seventh birthday."

Robert claimed it was important to the parents-of-three to explain George's role in The Firm at a "controlled moment of their choice," as they refrained from talking about his "life of future royal service and duty" to give him a "normal family upbringing," it was reported.

Learning of the duties that come with being a royal is no easy task, but it seems George's sister is more than willing to lend a helping hand. During Queen Elizabeth's funeral earlier this month, the young princess was adorably seen instructing George on what to do when their great-grandmother's casket past them.

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In a short video of the sibling interaction, Charlotte told her older brother, "You need to bow," as he listened intently to her instructions.

Daily Mail reported on George's comical remark.