Royal history is usually divided into reigns but there are other more personal events which bookend various chapters. Take before and after Prince Charles clapped eyes on a teenage Lady Diana Spencer or before and after Prince Andrew started to hang out with his new chum Jeffrey Epstein.
In January 2020 the royal story lurched off of the rails with Harry and Meghan, Duke and Duchess of Sussex suddenly making a break for it in a nearly-thinkable plot twist.
You know what has happened since then, the $200 million worth of deals, their turning to prime-time confessor Oprah Winfrey, the designer chicken coop.
For years now, this saga followed a fairly predictable course but, over the course of the last 24 hours, one thought has been increasingly running through my head: Are we witnessing the beginning of the end of their Megxit dream?
Oh, I don't mean that the couple might suddenly be hankering to return to the royal fold, to long grey winters and a country that has yet to fully embrace the power of crystal sound baths.
Nor do I mean that the royal family might suddenly have decided that all is forgiven and be encouraging them to move their Diptyque candle collection back into their UK home, Frogmore Cottage.
Rather, the royal landscape has changed seismically in the last three days since the death of his grandmother the Queen and what is in doubt now is quite exactly where the Sussexes' chips might fall.
Rewind to 2020, when the world had recovered a smidge from the fact that two members of the royal family had had enough of bridge openings and hightailed it off to live the American dream. For a time there, the Sussexes seemed like they had just executed a supremely shrewd pas de deux. No more dull royal receptions and having to make small talk with visiting Albanian trade delegations; no more having to sit through a former member of Little Mix belting out the national anthem during interminable official church services; no more hours spent in the sun at Buckingham Palace garden parties.
The couple staked their new post-royal identity on them as brave escapees who were willing to spill the beans on how screwed up the institution of the monarchy really is. And that's a play that has worked, to some extent, in that it has kept them in the headlines.
Unfortunately, it is much easier to sell an "us versus them" narrative when they could cast themselves as two plucky souls willing to share their pain with Oprah in the face of the looming, unflinching edifice of the Palace.
Instead, what has happened in recent days is that the Queen's death has humanised the royal family in a truly unprecedented way, with her children and grandchildren showing no compunction about expressing their grief in public and to the masses.
There is suddenly not only sympathy but, perhaps even more interestingly, real understanding for the Windsors, the whole imperfect lot of them.
That feeling extends across the pond. The United States might have booted out the king in 1783 but the reaction in the States has been unexpectedly vociferous. The New York Stock Exchange held a minute of silence, Her Majesty's face was projected onto the Empire State Building and the news of her passing saw TV stations switch to rolling coverage.
Which is to say, will Harry and Meghan return to their home in Montecito later this month to find the tables have turned? And, has the wind changed only temporarily or is there a longer-lasting tectonic shift going on in terms of public feeling?
The consequences of this obviously goes far beyond their ability to find a sympathetic TV host's ear but extends to their marketability. Netflix, Spotify and Penguin Random House, among others, have all done massive deals with the duke and duchess, who not long after getting to the United States saddled themselves with a reported $15.4 million mortgage.
If Harry and Meghan's signature flavour of anti-Palace rhetoric suddenly starts to seem a bit on the nose and runs counter to the way public opinion is going, what implications could that have for their commercial prospects?
Something else has come into focus as events have unfolded since Her Majesty' passing, and that is, how hollow the Sussexes' US life seems to be. Sure they talk the talk about their intention to do good but all that ambitions that never seems to actually translate into ongoing action. Somehow the glitz and glam and paling about with Oprah obscured the emptiness of it all.
Now, the vapidity of their new careers come more painfully into focus.
In February 2021, after their one-year post-Megxit cooling-off period, the Palace stripped him of his military titles and both of them of their royal patronages, with the Palace putting out a statement which referenced "a life of public service".
Four minutes later a spokesperson for the couple responded with the statement concluding with the spiky line, "Service is universal."
As bolshy as their pronouncement might have been, they were right. Any and all of us can do real good in the world but that requires commitment, perseverance and putting in the work, even when the cameras are turned off.
But unfortunately what Harry and Meghan are very good at is the saying and not the doing.
In the 21 months since that service line, the couple has failed to achieve anything meaningful or noteworthy on the charitable front, aside from putting out self-important press releases with the enthusiasm of two people who have a surfeit of A4 people to get through.
The monarchy might be a ridiculously antiquated institution; the very concept of a person, through the accident of birth alone getting to rule nations is simply a preposterous one; but the royal family of today genuinely makes a positive contribution. The causes that occupy much of their time – climate change, mental health and domestic violence, to name a few – are some of the most urgent issues of our time and the Palace has done a remarkable job of transforming the Crown into a more robust and dynamic prospect.
By contrast, the Sussexes' endeavours seem like a never-ending stream of exercises in image management, a constant stoking of celebrity status. Look at Meghan's 40th birthday initiative which fizzled from view almost immediately and their scattergun interventions on issues ranging from paid parental leave to disinformation, to name just a few. All of these are important causes but the couple's hype never seems to come with any sort of follow-through.
Which is why I wonder, as Harry and Meghan joined William and Kate, Prince and Princess of Wales on their walkabout outside Windsor Castle yesterday, were they reminded of what it was like to be a part of something bigger? Something with real meaning and purpose?
The motto of the Prince of Wales, Ich Dien (or "I serve" in German) dates back to 1346 and Edward the Black Prince. While they probably shouldn't print it on their stationery, if ever there was something that belonged to William and Kate that the Sussexes should permanently borrow, it is this.
• Daniela Elser is a royal expert and a writer with more than 15 years' experience working with a number of Australia's leading media titles.