The three attend school near their new manor house outside Paris, a 90-minute plane trip from Monaco, the principality ruled by "Papy," Prince Rainier, 77. For breaks, they go home to a house in Saint-Rémy, France, their primary residence until last June; to the Austrian estate of stepdad Prince Ernst August, 46; or to their Monaco villa near Rainier's palace and the homes of uncle Albert, 42, aunt Stephanie, 35, and cousins Louis, 7, Pauline, 6, and Camille, 2. It's a privileged life, but the teens are by all accounts charmingly unspoiled. "They don't act like royalty," says one pal. "They're just ordinary."
Credit goes to Caroline, 43, who shielded her brood from the limelight by settling in Saint-Rémy after Casiraghi's 1990 death in a speedboat accident. Since January 1999 she has given the children a stepfather who may be volatile but with whom they get on well, plus a half sister, 16-month-old Alexandra. Oh yeah—Mom can also throw a mean party. Last June Caroline invited her kids' friends to a school's-out bash at an abandoned factory in Provence. Afterward Andrea, Charlotte and Pierre spent the night sleeping on the floor with 50 guests. Slumming? Not quite. "They'd covered the broken windows with curtains and sparkling lights," says a guest. "It looked like a castle."