Then he dropped the bombshell: Someone wanted them dead.
Bit by bit, family members saw sinister motives in even ordinary encounters. They retreated to their chateau, where Tilly took away their clocks, their calendars, their sense of time. One by one, they relocated with him to Oxford, England, then returned to their Bordeaux home where, the family lawyer said, they were cut off from friends and relatives.
"There was no day and no night," said the lawyer, Daniel Picotin.
Protection didn't come cheap: They sold their ancestral home, apartments, jewels, wine collection, luxury watches—more than 4.5 million euros in all—handing over the proceeds to Tilly, a man they saw as their protector, even their "guru."
The family was in hiding for nearly a decade before two of the adult children realized Tilly wasn't what he appeared.
"We were a normal family that stumbled into an abnormal story," Christine de Vedrines, who first sounded the alarm when her employer declared she and her family were being brainwashed, said in a radio interview. "Thierry Tilly is not a guru; he's a predator."
Tilly, whose manipulation of the de Vedrines family has led to comparisons to the Russian mystic Rasputin's legendary influence over the tsar, was sentenced to eight years in prison on Tuesday, convicted of arbitrary detention, using violence against vulnerable people and abusing people weakened by "psychological subjection."
Tilly held the family in his sway from 2000, a year after he was hired by Ghislaine de Vedrines to work at her secretarial school, until 2009. During that time, he led 11 people—ages 16 to 89—to believe there was a secret plot against their lives, according to court testimony.
Skeptics like Ghislaine's husband were shunned, according to Picotin.
The presiding judge, Marie-Elisabeth Bancal, described it as a "Machiavellian plot."
Picotin said the family's money was poured into a fake charity that Tilly, now 48, claimed was set up to pay the Vedrines' "protectors."
"He persuaded them they were surrounded by enemies," Picotin said.
With the trial over, Christine de Vedrines told the Sipa news agency the family would somehow rebuild.
"Eight years is a small price to pay for what he did to our family and children," said Christine de Vedrines, who Picotin said was locked up by the family for nearly two weeks and deprived of sleep and food before managing to get away.
Picotin said he hopes to help the family reacquire their ancestral home. As for the rest, he said, "it's all gone."
A Tilly accomplice, Jacques Gonzalez, was sentenced Tuesday to four years in prison.
Tilly's lawyer had argued that the family from the 13th-century village of Monflanquin in southwestern France had acted willingly.
"These 11 family members aren't ill, have their feet on the ground, a level of self-awareness. Eleven people manipulated by mysterious forces by a single man? The legal basis for the case is weak," lawyer Alexandre Novion told The Associated Press.
Novion denounced testimony about the family's mental state, saying a man's freedom should not depend on "an old Freud tome found in a psychoanalyst's attic." He also said Gonzalez—and not Tilly—was the ringleader and absconded with all the money.
According to court statements, in the years after Ghislaine de Vedrines met Tilly in 1999 and introduced him to the rest of the family, he played relatives against each other, creating group paranoia and preying on the family's weaknesses.
"He is a liar, a fantasist," Ghislaine de Vedrines said at the outset of the trial, according to Europe 1. "He kidnapped us, saying anything and everything, and set us against each other."
Tilly was arrested in Switzerland in 2009.
Although Tilly was deemed mentally stable during his trial, French media have reported that he has a history of lies and exaggerations. Tilly claimed before the Bordeaux court that he was a member of the Habsburg dynasty and that he once almost played soccer for Marseille.
Tilly remained defiant Tuesday despite the conviction, saying he is a British citizen and will take his case to the European Court of Justice.
"(The trial) has only just begun," Tilly declared.
His lawyer, meanwhile, said he was not aware that his client was a British citizen.
Picotin said he had hoped Tilly would get a longer sentence. "I'm sure that if he gets out he'll begin again," the lawyer said.
The case raised echoes of another controversial trial involving France's richest woman, 90-year-old L'Oreal heiress Liliane Bettencourt, who was swindled by a French tax lawyer into handing over to him a private Seychelles island.
Thomas Adamson can be followed at http://Twitter.com/ThomasAdamsonAP
Lori Hinnant can be followed at http://twitter.com/lhinnant