The world is used to seeing pictures of an adorable Prince George making mischief at royal family events.
But the third in line to the throne - who celebrates his sixth birthday tomorrow - is actually more "shy" and "serious" than people may realise.
A royal insider told The Sun's Fabulous that Prince William and Kate Middleton's eldest child has become more "independent" since the arrival of sister Princess Charlotte, four, and one-year-old brother Prince Louis.
"With younger siblings Charlotte and Louis taking a lot of the attention at home, George is learning to be more independent," the friend revealed of the young royal, who will start Year 2 at Thomas's Battersea in September.
"Yes, he has been protected from some of the realities about being third in line to the throne, but it is almost as if he is hard-wired to feel a sense of responsibility."
They added that he is known among those who spend a lot of time in royal circles to be both naturally more serious and shy than his little sister.
However, once George becomes comfortable in a situation he turns "playful" - a side royal fans have been delighted to see at public events.
At Trooping The Colour last month he was spotted pulling faces on the balcony, and he was also seen being cheeky with cousin Savannah Phillips at Princess Eugenie's wedding last October.
The Duke of Cambridge, 37, has also repeatedly described his firstborn in interviews as "a handful".
"George likes people. Whether he has learned this from his father or it simply comes naturally, he first likes to be sure that he can trust them," the source added.
The little boy will mark his birthday tomorrow with a small, low-key party at his Norfolk country home Anmer Hall.
It follows the Cambridge's family holiday to the Caribbean island of Mustique, where many had originally believed the youngster would be celebrating.
- This article first appeared on Yahoo