Now, months after she lost that legal battle, 25-year-old Jean-Victor Meyers is replacing his grandmother as a director of the cosmetics giant her father founded.
It is the unassuming Meyers' latest reward for his long-standing loyalty and role as family peacemaker.
He was put in charge of the heiress' physical well-being last October after his mother won a long-running legal battle with Bettencourt to control the fortune. A judge declared the 89-year-old daughter of L'Oreal's founder to be mentally unfit.
Meyers, described as well-bred and discreet by sources close to the matter, is an enigma for watchers of L'Oreal strategy in the cosmetics world.
The eldest son of Bettencourt's estranged daughter Francoise Bettencourt-Meyers and her husband Jean-Pierre Meyers will now join both his parents on L'Oreal's board and is not expected to dissent from the family line.
Jean-Victor is the favourite grandson. He has been raised in a cocoon and I hardly see him going against the will of his mother, said one of the sources, who spoke on condition of anonymity.
Described as very close to his grandmother, Meyers has been a member of the supervisory board of Bettencourt family holding company Tethys since January 2011.
That appointment was the first disruption in the sheltered life of a privileged young man who spent his holidays on the Megeve slopes in the French Alps or at the family country home of Arcouest in Brittany.
A BLANK SHEET
He hardly knows anything about the hardships of life and has not much business experience, one source said of Meyers. He studied economics and management at the Institut Superieur de Gestion -- not among the elite colleges usually favoured by the upper echelons of French finance.
He took summer courses at St. John's University in New York and UCLA.
In addition, his resume mentions a 2006 summer job at the French Red Cross and a 2009 sales stint at luxury leather goods maker Louis Vuitton on Paris' elegant avenue Montaigne.
Over the last two years, he spent several months with L'Oreal's divisions in France and abroad.
Another source close to the company described him as smart and very mature for his tender age.
L'Oreal Chief Executive Jean-Paul Agon said on Tuesday that the replacement of Bettencourt, 89, by her grandson on the board signalled the family's continuing commitment to the cosmetics group.
Agon said the generation change would have no effect on a shareholder agreement between the family and Swiss food group Nestle
The three family representatives on the board would continue to vote as a block, he said.
Bettencourt lost control of her business affairs -- including her 30 percent in L'Oreal -- to her daughter in an October judgment on the basis of a medical examination that concluded she was suffering from a form of dementia.
(Reporting by Dominique Vidalon, additional reporting Alice Cannet; Editing by Chris Wickham and Paul Taylor)