Prince William is said to have rubbished his brother's claims that he is "trapped" by royal life.
He reportedly took exception to Prince Harry's description in his explosive Oprah interview.
Harry claimed his brother and father were shackled by life in the royal family in the tell-all with wife Meghan Markle.
But according to an in-depth Sunday Times profile of the future King, William plans to be a "robust" ambassador for the Crown when he takes the throne.
A source close to the Duke of Cambridge told the newspaper said Harry's interview left William "reeling."
Harry told the world that William was trapped within “the system … My brother can’t leave that system, but I have.”
In his only public remarks on the interview, William briefly addressed bombshell racism allegations after Meghan and Harry claimed a member of the royal family asked how dark Archie's skin would be when he was born.
Asked by a reporter if the royals were racist, William replied: “We’re very much not a racist family.”
The brothers are said to have been in contact since the interview, in which Harry said he hoped to mend the growing rift between the pair.
Buckingham Palace issued a statement in the aftermath saying racism allegations would be taken seriously and handled privately, adding "recollections may vary."
The Queen was said to be planning to handle the issue personally and would be speaking to Meghan and Harry in California in a phone call.
But as the monarch takes charge of the fallout, sources told the Sunday Times her eventual successor was stewing over his brother's description of himself as "trapped".
A close friend of both brothers reportedly described Harry’s comment as “way off the mark” and claims William does not see his royal duties that way.
“He has a path set for him and he’s completely accepting of his role. He is very much his grandmother’s grandson in that respect of duty and service.”
Prince Charles is next in line for the throne, and William is possibly still decades away from becoming King.
But he is said to be focused on modernising the Royal Family, as a series of scandals in recent years enveloping the monarchy raises questions about its place in a new age.
In a 2016 BBC speech, the royal spoke about whether he planned to model his approach on the Queen or Prince Charles' examples.
While the Queen has preferred to take a 'passive' approach and keep far away from politics, the Prince of Wales has been more outspoken in publicly championing his environmental causes.
In the speech five years ago, William said: “I’ve got my grandmother who takes more of a passive role. She’s above politics and is very much away from it.
"And then I’ve got my father, who minds an awful lot about the charities he’s involved in and really digs down into his charitable areas as much as you can. I haven’t an equal idea as to how my role could benefit everyone in the future.”
He concluded: “In the Queen I have an extraordinary example of someone who has done an enormous amount of good and she’s probably the best role model I could have in front of me.”
He is described by insiders in the Sunday Times profile as a "small 'c' Conservative" who values tradition and duty - but is said to have no ambitions to 'meddle' in party politics.
William was reportedly unhappy about the position the government put the Queen in when Boris Johnson had the monarch order parliament to be prorogued two years ago during the height of Brexit squabbles.
The move was later ruled to be unlawful and was widely seen as unconstitutional and a threat to the delicate balancing act of the relationship between Westminster and the monarchy.
In William’s reign there will be “more private, robust challenging of advice”, according to the future King's close pals, the newspaper reports.
The Mirror has contacted Kensington Palace for comment.
