King Charles has made a positive impression since taking up the role, but the coming weeks will be crucial as he straddles the roles of both son and King to bury his "darling Mama", one of the greatest leaders in the world, writes Joy Reid.
There are two events happening simultaneously right now. The end of one sovereign's reign and the birth of another.
King Charles III has been the "next in line" for 70 years. That makes him arguably the best prepared monarch, not to mention the oldest ever, to take the British throne. He now takes on the job he's waited a lifetime to fulfil, at the same time as he negotiates his own grief at the loss of his mother and leads the world in theirs.
In her wisdom, Queen Elizabeth II had preempted this day and for the past few years has been laying the groundwork for this moment. Her son standing in for her at key moments and events, preparing him and the world for when he takes centre stage.
His first address as King Charles III was compelling and poignant. And as he shook hands with the mourners and well-wishers outside Buckingham Palace with his wife, the Queen Consort, it had an air of festivity. People were delighted to see him. He was smiling, the Queen Consort was smiling. People were singing God Save the King. The monarchy doesn't stop. The Queen's last breath is followed by his first breath as King. And King Charles is showing right from the outset that he's a leader that is willing to get amongst his people.
The country may be in a time of national mourning but at the same time, history is also being made with the beginning of a new King. His diary over the next few days is full not of last-minute errands ahead of his mother's funeral but instead with duties required of a monarch - starting with a tour to the UK parliaments.
But he has challenges ahead. How will he, a man known for speaking on issues he's deeply passionate about, be able to suddenly switch to the absolute neutrality that's required of the crown?
He hinted at it in his speech.
"My life will of course change as I take up my new responsibilities. It will no longer be possible for me to give so much of my time and energy to the charities and issues for which I care so deeply. But I know this important work will go on in the trusted hands of others."
He's been a long-time campaigner for climate change issues and organic farming (somewhat ahead of his time on these issues). He's been forceful at times with his opinions and is known for petitioning government ministers with his thoughts on these topics. His blatant advocacy in this space is over, he will now have to operate in a different way, but his speech suggests he feels he can pass on the baton.
His son Prince William, now the Prince of Wales, is also devoted to climate change which aligns with Māori kaitiakitanga.
King Charles III has long embraced multi-cultural multi-faith communities and this value is likely to be taken into his role as King, as seen in his speech.
"Whatever may be your background or beliefs, I shall endeavour to serve you with loyalty, respect and love, as I have throughout my life."
For a man in his 70s, the King shows no sign of slowing down. He appears determined to keep the monarchy alive.
Whether it will is not a given.
According to a YouGov poll in the UK last December, he has been growing in popularity, with almost two-thirds of people seeing him in a favourable light. But opinion polls have consistently shown him to be less popular than his mother or his son Prince William.
The question is, can he win over the last third? And a greater question, will the other 14 countries he now becomes head of state of (including New Zealand) continue to support the monarchy? Or is it time to revisit the conversations about becoming a republic? King Charles has already made clear he is ready to have those difficult conversations about change if that's what is wanted.
He comes into the job too in circumstances his mother never faced when she took over. Given the evolution of media (including the tabloid era), the whole world knows so much about him, his past failings and gaffs. He has been subject to unsympathetic portrayals about his marriage and affair on TV shows and his failed marriage to the late Princess Diana still hangs over him more than three decades later.
While public opinion has changed a lot since then, some can't move past that. The Queen has done her best to help him rise above this and was determined to integrate his second wife of 17 years, Camilla, into royal life; making clear the title she wanted her to have when the time came - Queen Consort. By stating that before she died, the Queen made it known that Camilla has her full support in the role and this has meant that the challenges of the past don't appear to resonate so strongly with the public as they used to. This bodes well for King Charles III.
It's very different being a monarch than being an heir and regardless of his 70 year apprenticeship, how successful his reign will be depends on the days, weeks and months ahead.
He's made a pledge to his realms and the Commonwealth to "serve throughout the remaining time God grants me". And in his first 48 hours as King, he's made a positive start. Those pictures of him interacting with the crowds are telling and show that this handover has the potential to be seamless.
But we simply don't know what he will be like as King. He has a big fortnight ahead as he straddles the roles of both son and King to bury his "darling Mama", one of the greatest leaders in the world who has left Charles with very large shoes to fill.