Following the Queen's death at the age of 96, the royal family will be supporting each other immensely over the coming weeks and months. As Charles becomes King, there are big changes in store for his wife Camilla, now Queen Consort, and his two children, Prince William and Prince Harry.
The King will also lean on his siblings, Princess Anne, Prince Andrew and Prince Edward, as the four of them grieve the loss of their mother. Being the eldest son, Charles has been passed on enormous responsibilities handed down by generations of royal monarchs.
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Charles and his younger sister Anne were born just 21 months apart, and as the eldest of the four siblings, they grew up the closest.
Inevitably, the pair forged a special bond and are known to share the same hobbies and interests, including a love for all things Scottish and the countryside.
Their close relationship was made even stronger at the Queen's bedside, as Charles and Anne were the only senior royals present at Balmoral when she died on Thursday.
They were able to mourn privately together before Prince Andrew, Prince Edward, Prince William and Prince Harry arrived to say their final goodbyes.
It is unknown yet whether King Charles will bestow a new title on Anne, who currently holds that of Princess Royal, but the evidence suggests her importance will be regarded highly.
Anne is often referred to as the hardest working royal, battling it out with her older brother over who attends the most engagements.
Anne, who is the Queen's only daughter, accompanied her mother's coffin on its final journey through Scotland.
She is expected to be a key figure in the funeral proceedings and future events.
As to Prince Edward, it is likely that he will become the Duke of Edinburgh, a title his father, Prince Philip, was given when he married Princess Elizabeth in 1947.
Following his death last year, it was expected to be held by another member of the royal family.
The title fell to Charles as the oldest son, though it has always been understood that the Duke wanted his youngest son, the Earl of Wessex, to inherit his title.
On Charles' accession to the throne, the title can now be regranted to Edward - a decision that lies with the new King.
Edward previously told the Daily Telegraph: "It's a very bittersweet role to take on because the only way the title can come to me is after both my parents have actually passed away.
"It has to go back to the Crown first. My father was very keen that the title should continue, but he didn't quite move quickly enough with Andrew, so it was us who he eventually had the conversation with.
"It was a lovely idea; a lovely thought."
In another interview with the BBC, Edward added: "It was fine in theory, ages ago when it was sort of a pipe dream of my father's... and of course it will depend on whether or not the Prince of Wales, when he becomes King, whether he'll do that, so we'll wait and see."
If Edward is given the title, his wife Sophie will become the Duchess of Edinburgh - a title which was held by the Queen.
Dickie Arbiter, a former press officer for Buckingham Palace, previously addressed reports that Charles would block his brother taking the title.
Arbiter claimed the Prince of Wales was simply waiting and had no plans to defy his late father's wishes, according to The Sun.
He said: "That Prince Edward will become The Duke of Edinburgh in the next reign was his father's and is his mother's wishes and Prince Charles won't go against those.
"It won't happen immediately, but by 2029, when Edward turns 65, it will."
He added: "Time for speculation, without substance, to cease."
The title has long been expected to be passed to Edward and in 1999 Buckingham Palace announced he would succeed his father in "due course".
Following Prince Philip's death, Edward and his family became increasingly important to the monarchy - and it can be assumed they will do so even more after the Queen's passing.
Sophie was called the Queen's "rock" after she became a widow, and one courtier claimed: "If you're asking who is Her Majesty's favourite child, it's none of them, it's her daughter-in-law."
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