How a Baby Changed William and Harry's Royal Relationship

With the news that the Duchess of Cambridge, Kate Middleton, is pregnant with a second royal baby, a new biography of Prince Harry sheds light on the evolution of his relationship with his older brother, Prince William, Duke of Cambridge, since the birth of Prince George last July.

“It’s fantastic to have an addition to the family,” Harry said about his nephew, as royal-family biographer Penny Junor writes in Prince Harry: Brother, Soldier, Son. “I only hope my brother knows how expensive my baby-sitting charges are.”

And if Will’s change in behavior since George’s birth is any indication, the birth of his second child will likely mean Will and Harry will spend less time playing around with friends at clubs and more time playing with babies. Junor writes in Prince Harry:

William’s focus has changed. He is no longer in the military, no longer up for partying till dawn, or tripping over guy-ropes in the early hours at Glastonbury. He is more interested in getting an unbroken night of sleep and listening to George’s growing vocabulary.

The biography quotes “a friend” adding that Prince Harry “loves” having dinner with Will, Kate and George and says that’s basically what the brothers’ nights out are like now, even though Harry does not appear to show signs of settling down himself anytime soon.

It would be a different night from the one they would have spent three or four years ago, which would have been, ‘Who can remain standing longest?’ … They are very, very close and Harry loves the whole domestic bit which his brother’s doing now … I think he sees what his brother’s getting out of it …

The book will be released tomorrow, ahead of Prince Harry’s 30th birthday next week.

Write to Olivia B. Waxman at olivia.waxman@time.com.