When he is eventually crowned in just over two weeks, King Charles will be surrounded by his close family. But several key relatives will be missing from the Westminster Abbey congregation - his daughter-in-law Meghan Markle and his two youngest grandchildren Prince Archie and Princess Lilibet.
The trio are not accompanying Prince Harry to the Coronation on May 6 - and will instead stay at home in California.
It marks what appears to be a change in their bond, which seems to have started on a positive note, with the pair even sharing several of the same interests.
But now, with Meghan set to miss one of the biggest days of her father-in-law's life, here we take a look at their changing bond...
First impressions
When Meghan first started dating Harry, her first meeting with Charles and Queen Camilla came at Clarence House.
And in his memoir Spare, Harry recalls them all enjoying tea together and how Meghan curtsied when she met her future father-in-law, who quizzed her on her acting career, thinking she was in a soap opera.
Harry writes: "He had a lot of questions about Meg’s career, and he looked impressed by the way she answered. Her confidence, her intelligence, I thought, caught him unawares."
Meanwhile, according to his unauthorised biography Meghan: A Hollywood Princess, Andrew Morton writes that Meghan clicked with Charles over their interest in "sustainable organic food, classical music and architecture".
Wedding gesture and unexpected response
After a period of dating, Harry and Meghan decide to wed with a lavish ceremony at St George's Chapel in Windsor.
But despite the beautiful day, there had been tension leading up to the wedding due to Meghan's dad Thomas Markle.
With less than a week to go before the big day, he announced he would not be attending, leaving the bride with nobody to walk her down the aisle.
Meghan's future father-in-law Charles then offered to step in telling his daughter-in-law he would be honoured to escort her to the altar of the chapel.
But according to a book, her reply to this gesture was somewhat unexpected by the then Prince of Wales.
Writing in Queen of Our Times, author Robert Hardman says: "The reply, according to one friend, was not quite what he was expecting: "Can we meet halfway?'"
"Here was an indicator that this was no blushing bride, but a confident, independent woman determined to make a grand entrance on her own."
Endearing nickname
And it seems Meghan's determination despite turmoil behind the scenes is what earned her an unusual yet endearing nickname from Charles.
It is said he began calling her 'Tungsten' as according to palace sources, she is "tough and unbending".
A source previously told the Mail On Sunday : "Prince Charles admires Meghan for her strength and the backbone she gives Harry, who needs a tungsten-type figure in his life as he can be a bit of a softy. It's become a term of endearment."
Money rows
However, despite the promising start, it seems worries over money were an issue from the start.
In Spare, Harry claims Charles asked if Meghan planned to carry on acting as "there's not enough money to go around".
He claims his father told him: "I can’t pay for anyone else. I’m already having to pay for your brother and Catherine."
Meanwhile, in the months after the wedding and the birth of Charles' third grandson Archie, relations between Harry, Meghan and the rest of the royals began to deteriorate.
And in early January 2020, the couple made the shock announcement that they would be stepping back as senior royals and moving to North America.
Eventual reunions
After moving to California, Meghan first returned to the UK last spring, when she and Harry stopped off in Windsor en route to the Invictus Games in the Netherlands.
The couple had what has been described as a short, tense meeting with Charles and Camilla before they met up several months later at the time of the Queen's Platinum Jubilee celebrations.
On that occasion, they brought Archie and Lilibet, who was approaching her first birthday, with them - and Charles was reunited with his grandson and met his granddaughter for the first time.
A royal source said at the time: "The prince and the duchess were absolutely thrilled to see them.
“The prince, of course, hasn’t seen his grandson Archie for a bit of time and so it was very, very, very special to have some time with him.
“He hadn’t met Lili, his granddaughter, and so to meet her was very emotional, a very, very wonderful thing.”
Balmoral ban
However, Meghan and Charles next appeared at loggerheads on the day the late Queen died last year.
When the late Queen entered her final hours at Balmoral last September, members of her family raced to be with her.
Among them were Prince William, Prince Andrew, Prince Edward and his wife Sophie, who took a flight from London to Scotland.
Prince Harry, who is estranged from some of his royal relatives, took a separate private jet and wrote in his memoir Spare how he was told wife Meghan shouldn't come with him as Kate wasn't going either.
He explains: "He started to lay out his reason, which was nonsensical, and disrespectful, and I wasn’t having it. Don't ever speak about my wife that way.
"He stammered, apologetic, saying he simply didn't want a lot of people around. No other wives were coming, Kate wasn't coming, he said, therefore Meg shouldn't."
Coronation snub but photo tribute
So when it came to deciding on whether to attend the Coronation, it was revealed Meghan would be staying at home with Harry attending solo.
Archie turns four on May 6, the same day as the historic event at Westminster Abbey with the couple's biographer Omid Scobie confirming Archie's birthday "played a factor in the decision" and he expected it would be a "fairly quick trip to the UK" for Harry.
But despite her not attending, it appears the King has made a touching gesture as Meghan does appear in a souvenir programme for the King’s Coronation in a charming family portrait.
The 84-page official souvenir, which costs £20, went on sale on Monday ahead of the big day.
Among its pages is a full-page photo of Harry and Meghan alongside Charles, Queen Camilla, the Prince and Princess of Wales and their children - Prince George, Princess Charlotte and Prince Louis. The photo was taken in 2018 to mark the King's 70th birthday.
