Prince William is second in line for the throne, but taking on the kingship has more to do than bloodline, it also requires rigorous prep—and the 35-year-old royal has already had decades of practice. He started training at a young age under the guidance of his grandmother, the Queen.

"There has always been a special closeness between William and the Queen, and she has taken a particular interest in him," Robert Lacey, royal historian and liaison to Netflix's The Crown, told People.

"When William became a teenager, she would have him at Windsor Castle and would open the state boxes and guide him through the papers. It was William’s constitutional education," he added.

Remember that red box scene from The Crown? William probably had a few of those moments, too. It's through these special briefcases that the sovereign receives documents to keep up to date with the British government, the commonwealth and the rest of the world.

However, William's training goes beyond reading current events. Starting in 2009, he reportedly underwent an "intensive" two-year training program designed by the Queen and his father Prince Charles, according to The Daily Mail. It was said to include working with different departments in the British government, private lessons from "constitutional experts" and briefings with high-profile figures, like then-Prime Minister, Sir John Major.

Through the years, the Prince has also taken up more royal responsibilities in the public eye, such as solo tours around the world and promoting charity work. This year, he stepped down from as an air ambulance pilot in order to take up more royal duties. He's also absorbed some of the responsibilities and engagements from his grandfather Prince Philip, who retired in August.

It will be a while before we see Prince William crowned, but we're already getting a taste of what his reign would be like. According to his brother, Prince Harry, he may plan on taking a contemporary approach. "We’re involved in modernizing the British monarchy," he said earlier this year.

"We are not doing this for ourselves but for the greater good of the people," Harry added, and hinted that he and his brother might not want the crown at all. "Is there any one of the royal family who wants to be king or queen? I don't think so, but we will carry out our duties at the right time."

Following William in royal succession are his children—Prince George, Princess Charlotte, his upcoming third child with the Duchess of Cambridge—and then his brother, Prince Harry.

Erica Gonzales is the Senior Culture Editor at ELLE.com, where she oversees coverage on TV, movies, music, books, and more. She was previously an editor at HarpersBAZAAR.com. There is a 75 percent chance she's listening to Lorde right now.