When the Duke of Sussex paid an albeit brief visit to his father and stepmother at Windsor Castle this month, it was said to be a friendly affair which left the Prince of Wales and Duchess of Cornwall pleased to catch up.
Following a page-turning biography in which an author claimed: "Harry can't stand Camilla, he doesn't want Camilla to be Queen," it was just the moment to smooth over old wounds for a new era of cross-Atlantic calm.
But that short encounter has done little to quell fears the Duke is to turn his sights on the Duchess in his next forthcoming round of media revelations.
The Duke, whose autobiography is out in the autumn, "needs a new target and she will do", said one friend. "I'm sure he will say some unkind things about her, or try to make her a 'baddy', but that doesn't mean it's real."
Of reports that the Duke will not return to Britain for his father's future coronation, the friend added: "If the strategy is to create drama, this creates drama."
Clarence House has this week firmly denied a report in Private Eye that a "red line" has been drawn by the Duke of Sussex, who allegedly said he has "no intention" of attending the coronation of a future King Charles if he is crowned side-by-side with Queen Camilla.
Sources pointed out that while news the Duchess will one day be known as Queen was a surprise to members of the public, it would not be a shock to a Prince who would have been party to palace thoughts on the matter since his father re-married in 2005.
Return for the Platinum Jubilee
A spokesman for the Sussexes declined to comment and has not yet confirmed whether the Duke and Duchess will return to Britain for the Platinum Jubilee.
The relationship between the Duchess and her younger stepson has become an unexpected talking point in recent weeks, after Tina Brown's Palace Papers depicted a long history of resentment from the Duke which had left him "very angry" that she will one day be "Queen Camilla".
In fact, said sources, their interactions have not always been difficult. The young Prince Harry was more likely to act as ice-breaker to smooth over their meetings with his father and brother.
One characterised the Duke's historic approach to her as "acceptance, occasional pangs of guilt and ambivalence".
The Duchess of Cornwall was the first member of the royal family to invite the Duchess of Sussex to lunch after she moved to Britain.
But her relationship with the Duke is said to have worsened after his public criticism of the Prince of Wales.
Harry 'tended to ignore' Camilla
As the Duke spoke more about his mother's memory, one source speculated, his thoughts on the Duchess hardened.
Towards the end of his time in the royal family, before moving to California, another claimed the Duke of Sussex had tended to ignore the Duchess of Cornwall's presence in private, despite several warm public appearances together.
The Duke's autobiography, which he has promised is "a first-hand account of my life that's accurate and wholly truthful", is expected to detail his many memories of Diana, Princess of Wales, including the unhappy end to his parents' marriage.
It is due to be published in October.
One royal source insisted it would be a "surprise" to read the Duke of Sussex particularly taking aim at the Duchess of Cornwall. However, friends remain concerned that having criticised his father and brother publicly, she is the next obvious "easy target".
"It's another story that has not been shut down that allows the saga to continue," one said.
The Sussexes' team have not commented about the content of the forthcoming book.