It seems Princess Charlotte is adjusting spectacularly to the arrival of her younger brother, Prince Louis, who was born April 23. A source close to the Royal family told Us Weekly that the 3-year-old is so beholden with him that she "won't leave his side."
"Charlotte is really enjoying having a younger brother to play with. She's taking her big sister duties very seriously. She won't leave baby Louis' side," the source said, adding that a similar bond exists between her and her older brother, Prince George, 4, who is reportedly "protective" of Charlotte.
"Charlotte is just like him. They have a great bond, and a similar connection is growing between Charlotte and Louis," the source added.
"They like to make a fuss on the kids' birthdays," the insider said. "There is always cake, her favorite dinner and a lot of presents."
The toddler was surprised with a cake to share with her classmates at school, where she attends Monday through Thursday for half-day lessons, and she was also met with a celebration back home at Kensington Palace.
"She's not afraid of a grazed knee and it's not going to stop her from running around. She moves at the speed of light!" the source said.
As for Middleton and Prince William, the third addition to their family makes them extremely happy, too.
"They are soaking up every minute they can," the insider said. "Their dream was always to have three kids."
The Duke and Duchess of Cambridge unveiled the first image of Prince Louis on Instagram Saturday.
"The Duke and Duchess of Cambridge are very pleased to share two photographs of Princess Charlotte and Prince Louis, taken by The Duchess at Kensington Palace," the caption for the image showing Prince Louis read. "This image of Prince Louis was taken by The Duchess of Cambridge at Kensington Palace on 26th April. The Duke and Duchess would like to thank members of the public for their kind messages following the birth of Prince Louis, and for Princess Charlotte's third birthday."
Along with the photo, the family also shared an adorable image of Prince Louis and Princess Charlotte, showing her kissing Louis on the forehead.
Louis Arthur Charles was born Monday, April 23. He is the second son of the couple and will be fifth in line for the throne.