Queen Elizabeth II changed the royal title protocols laid out by King George V in 1917 to allow all three of Prince William and Kate Middleton's kids to be styled prince or princess upon birth.
Prince Andrew currently holds the title Duke of York, which can only be passed on to a male heir. Prince Louis could inherit disgraced Prince Andrew's royal title when he gets married or his father Prince William becomes king.
Princess Charlotte had a big sister moment with Prince Louis during Trooping the Colour. Prince Louis refused to heed his big sister Princess Charlotte's advice when they were watching the parade during Trooping the Colour, according to a lip reader.