When Diana died, Harry was 12.
His mother's death became everybody else's property and he was woefully ill-equipped to deal with it.
Whereas William was 15 and becoming aware of his responsibilities and the importance of his future, Diana hadn't had time to "finish" Harry.
For her cuddly, smiley, gorgeously freckled baby, it had been all hugs and silliness, dressing up, practical jokes and hair-raising drives in country lanes with pop music blasting out of the car stereo.
With Harry, she hadn't got to the duty bit. And then suddenly, she was gone.
First, he had to attend her funeral watched by millions on TV.
And then there was the astonishing public reaction to his mother's death.
Harry was always by far the more emotional and sensitive brother, but for years he couldn't talk about her. He bottled his churning emotions up and blocked everything out.
Saddest of all - particularly given the close bond they share - until now, he and his brother never talked about Diana as a mother.
Instead, Harry rebelled. He partied. He fell out of nightclubs, he wore Nazi fancy dress, he had a drunken wrestle with friends covered in vomit, he was barred from a pub for allegedly calling a barman a "f****** frog", he hit a photographer. The list goes on and on.
When he was 16, Prince Charles was so worried he got his son to visit an addiction clinic to witness the dangers of drink and drugs. Joining the army probably kept him sane.
But recently - and certainly since falling in love with American actress Meghan Markle - he seems to have turned a corner and is finally addressing his mother's death and its impact on his life, head on and with courage.
He has learned how to grieve and to talk about all he has lost in a way that will make any parent weep and forgive him his silliness.
"I can feel the hugs that she used to give us and, you know, I miss that, I miss that feeling, I miss that part of a family. I miss having that mother to be able to give you those hugs and give you that compassion I think everybody needs."
He describes Diana's love: "Even if she was on the other side of a room you, as a son, you could feel it. She set up us really well. She gave us the right tools."
Some tools, yes, but not all. He still occasionally blunders. Last month he said in an interview that no one in the royal family wanted to be king - a sentiment that must have caused consternation with the Queen and Prince Philip.
Perhaps such brutal honesty is a legacy of his mother and her remarkable openness.