Princess Charlotte has melted hearts after viewers spotted her sweet gesture for brother Prince Louis ahead of his starring role in King Charles' Coronation.
The siblings were spotted holding hands as the ceremony got underway at Westminster Abbey this morning.
During the sweet moment, Charlotte could be seen with her hand on top of her brother's while she bowed her head, and the excited Prince looked on.
Reacting to the exchange online, one Twitter user wrote: "Prince Louis and Princess Charlotte. How sweet."
"Yall look at Prince Louis and Princess Charlotte holding hands behind their parents," said another.
She was also praised when she was later spotted helping out once again - this time sharing with her sibling.
"Did anyone catch this adorable moment Princess Charlotte sharing her book with Prince Louis. For her little age, she’s always looking out for others!" an impressed Twitter user said.
It is expected that Prince George, Princess Charlotte and Prince Louis will join the monarch and Queen Camilla as they leave Westminster Abbey at the end of the ceremony.
The youngster, who turned five last month, is also likely to join his siblings on the balcony at Buckingham Palace to enjoy the RAF flypast after the procession.
Prince Charles was four-years-old in 1953 when Elizabeth was crowned, and attended only part of the three-hour-long service.
He sat between the Queen Mother and Princess Margaret and did not take part in any of the processions.
King Charles III's Coronation is taking place at Westminster Abbey in London, where more than 2,000 guests are expected to be in attendance.
This is a stark contrast to the Coronation of his mother, Queen Elizabeth II, who was crowned in 1953, where 8,000 people were present.
King Charles and the Queen Consort will also travel a much shorter procession route than the late Queen.
It's reported that the King did want a larger procession, but there were worries of how much that would cost, said royal insiders.
Viewing areas are open along the 1.3 mile procession route, which stretches from Buckingham Palace, down the Mall via Admiralty Arch to Westminster Abbey.