The Royal Family have released a touching image of the Princess kissing her baby brother, taken by their mother.
The newest member of the royal family was born on April 23, 2018, and is getting used to his new position.
The photograph shows Louis receiving a tender kiss from his sister Princess Charlotte, on May 2, Charlotte's third birthday.
Louis appears to be sleeping soundly, as Charlotte puts a protective arm around her baby sibling and plants a kiss on his forehead.
The palace said William and Kate were "very pleased" to share the photographs, adding: "Their Royal Highnesses would like to thank members of the public for all of the kind messages they have received following the birth of Prince Louis, and for Princess Charlotte's third birthday."
The 36-year-old Duchess is a keen and accomplished photographer who has taken images of her children in the past.
The proud mom took the official photographs of her newborn daughter in 2015.
The photos of Charlotte showed the young princess being cradled by her older brother George at William and Kate's Norfolk home, Anmer Hall.
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