And each, more than anyone else in the world, is in a position to know just how the other feels -- about being in the spotlight, about the blessings and burdens of growing up royal, about losing a parent who was both the most famous woman in the world and, more simply, their mother. "They need each other in terms of moral support," says a friend of William's. "Since the death of their mother, even more so."

Their bond is based on more, of course, than shared pain. Both William and Harry love polo, country weekends spent with horses and hounds (when William sees a dog, he bounds right up to it, says a friend), and hanging out at fashionable London night spots.

And both also seem to possess similar tastes in female companions. Tall and slim, with long blonde hair and hyphenated last names, their teenage gal pals look virtually interchangeable in the grainy, long-range shots captured by paparazzi. William is often found in the company of young women like former PR agent Natalie Hicks-Lobbecke, 23, or Davina Duckworth-Chad, 22, a cousin. Both young women are members of the princes' elite social gang. "They all know each other," says Brian Hoey, author of 15 books on the British royals. "Their parents know each other. Their grandparents know each other."

Another of those linked to William is Emilia d'Erlanger, 19, the granddaughter of a viscount. Known to her chums as "Mili," the blonde beauty is said to share William's love of art history. Though she, like William, is expected to enter Scotland's University of St. Andrews in September, a friend insists, "romance is out of the question." And indeed at present, Mili appears to be equally chummy with Harry, with whom she sat at a July 29 polo match in Cowdray Park, south of London.

Around such stunners, Harry can turn playful and exuberant. He nodded and laughed when the hot dog vendor at a recent polo match offered to set him up with her teenage daughter. After another match in Gloucestershire, he let salesgirl Lizzy Ward, 17, ruffle his hair, and he roughhoused with Emma Lippiatt, 19, swirling her around, hoisting her over his shoulder and planting a kiss on her cheek. And he has been known to make off-color quips. "He has the smutty humor of his mother," says a family friend. "She used to love telling smutty jokes."