Remembering the Real (and Complicated) JFK Jr. on What Would Be His 59th Birthday: 'He Was Two People'

Editor’s note: This article was originally published on July 2. Monday marked what would have been John F. Kennedy Jr.’s 59th birthday.

It was 20 summers ago that John F. Kennedy Jr.‘s plane crashed into the Atlantic Ocean amid thick fog — killing him and his two passengers, wife Carolyn Bessette Kennedy and her sister, Lauren Bessette, on their way to a Kennedy family wedding.

Three lives, ended. And America’s most famous political family, dealt another fatal blow.

Now historian Steven M. Gillon has written the biography America’s Reluctant Prince, excerpted in PEOPLE and published on July 9, which offers the first in-depth examination of John’s life. It reveals a man far more complicated than he might have seemed.

“He said he was two people,” Gillon remembers John, 38, telling him once. “He said he played the role of John Fitzgerald Kennedy Jr., the son of the president. But at his core, he was just John.”

From the moment the 3-year-old saluted his father’s casket, “All the hopes and expectations transferred to him and he carried that burden his entire life,” says Gillon, who delved into John’s efforts to define himself separately from his father, the 35th president.

Gillon first met John when he was a teaching assistant in a history class John attended at Brown University and the two struck up a friendship. For the book, he interviewed some of John’s closest friends, some of whom have never spoken before, including Michael Berman, with whom John founded the wave-making George magazine in 1995.

John knew his name carried unimaginable privilege. But he also carried the weight of “Camelot,” the myth of the Kennedy White House spun by his mother, Jacqueline Kennedy Onassis, in the wake of his father’s assassination.

“Jackie told people she regretted naming John after his father,” says Gillon. “She realized it only added to the burden. The irony is that in the effort to honor her husband, she inadvertently made her son’s life more challenging.”

During one lunch with John, Berman, his magazine partner, “looked around and he saw everyone looking at John and he said, ‘It must be interesting being you. You don’t know a soul here, but they all know who you are,’ ” Gillon recounts.

“That’s not the weird part,” John replied. “The weird part is they all remember, and I don’t.”

Still, according to Gillon, “John understood the public viewed him the way they did and he accepted it. He understood what he represented to people.”

“No one,” says Gillon, “will ever live a life like John F. Kennedy Jr.”

RELATED: A Writer Remembers JFK Jr. in His Prime: George Magazine Gave Her ‘The Best Years of My Life’

In the public eye since birth, John always seemed so at ease in his own skin and he was full of “such decency and compassion.” But America’s Reluctant Prince reveals there was far more depth — and turmoil — than he let on, including the pressure he felt to live up to his name and the restlessness that kept him from thinking about it all too much.

He was a man in constant motion: Kayaking, skiing, rollerblading and playing football were just a few of his favorite pastimes. “If I had to stop and think about it all,” John once told friend Billy Noonan, “I would just sit down and fall apart.”

His final months, according to Gillon, were among his hardest. George was struggling, as was his marriage. But there was promise, too.

• For more on JFK Jr.’s world and sudden death, pick up PEOPLE’s 96-page special edition John F. Kennedy: An American Life, available now on Amazon and wherever magazines are sold.

RELATED VIDEO: PEOPLE Celebrates the Life of John F. Kennedy Jr. in New Commemorative Edition

“When I first met John in the ’80s, he referred to his father as ‘President Kennedy,’ ” Gillon says. “And then into the ’90s he referred to him as ‘my father,’ and in the last few years he referred to him as ‘daddy.’ It just suggested to me that he was becoming more comfortable with himself and he did not have to keep his father at such a distance.”

“He spent his entire life trying to figure out who he was and what he wanted to do,” Gillon says of John, “and in those final years he figured it out. What he discovered was that politics was part of his DNA. … I think he was ready to answer that call.”

But then it all came to an end.

“His whole life is about promise and what he would have become,” Gillon says, “and he will always be remembered for the promise that went unfulfilled.”