Prince George is a protective big brother to younger sister, Princess Charlotte.

On Monday, Kate Middleton delivered her third royal baby with Prince William. The Duke and Duchess of Cambridge's kids accompanied their dad when Prince William visited Middleton.

In a clip, the Duke can be seen holding his kids by the hand. Prince George and Princess Charlotte who are both attending school are still in their uniforms. The little princess was in the mood and showed everyone her royal wave as they walk on the way to the hospital. Meanwhile, her brother was too shy to greet the crowd.

As the video is about to end, Prince William let go of Prince George and Princess Charlotte's hands and the two walk ahead. Prince Charlotte approached Prince George and he put an arm around her shoulders.

Prince George and Princess Charlotte's visit to their mom and new sibling was expected. When Middleton delivered Princess Charlotte in 2015, Prince George was with Prince William too, to welcome the new addition to their family.

This has been a tradition. In fact, when Prince Diana gave birth to Prince Harry, Prince Charles arrived with Prince William.

According to a royal photographer, an ideal photo when Middleton leaves the hospital after delivering the new baby would be capturing the family of five.

"The ideal picture for us when they leave hospital is a family picture of William and the Duchess of Cambridge, George, Charlotte, and the new baby," Tim Rooke said. "That would be amazing, but we'll have to wait and see."

In related news, according to Queen Elizabeth II, Princess Charlottes rules over her big brother, Prince George. Earlier this year, the queen met 10-year-old school girl, Emily Clay, who won a Bible signed by Her Majesty for a school religious education project.

Queen Elizabeth asked Clay if she "looked after" her 6-year-old sister. "It's the other way around," their mom, Ellen, replied. "It's like that with Charlotte and George," the monarch quipped.

Princess Charlotte will retain her succession to the throne even if the new royal is a boy. Initially, royal sons took precedence over their female siblings, but this rule was changed in the Succession to the Crown Act in 2013.

Prince George and Princess Charlotte
Prince George puts a protective hand around Princess Charlotte's should during their visit to mom and new sibling. Pictured: Prince George, Prince William, Princess Charlotte at the Lindo Wing of St Mary's Hospital in central London on April 23, 2018. Getty Images/Daniel Leal-Olivas