Athens, Greece ? A few signatures in a Swiss office and it will be over: half the Onassis shipping fortune will pass to the young heiress who is one of the last descendants of a tormented family.

Athina Roussel, who reaches the inheritance age of 18 Wednesday, takes on a difficult role along with her great wealth.

What will she do with the fortune, estimated at $700 million to $1 billion, that has made her one of the world’s wealthiest teenagers? Can the granddaughter of Aristotle Onassis, the “Golden Greek,” end the bickering and bitterness that have marked her childhood and estranged her from her ancestral homeland?

The answers, it seems, will come only when she is ready to assume a more public profile. She rarely gives interviews and appears to cherish privacy as much as her grandfather thrived in the limelight.

Family sorrow, sniping

The cliche “poor little rich girl” has fit her well.

Her grandfather died brokenhearted two years after a 1973 plane crash killed his son Alexander. His other child, Christina, died in 1988, leaving her 3-year-old daughter Athina to be raised in Switzerland by her French-born father, Thierry Roussel, and his Swedish wife.

The fortune was divided between Athina’s inheritance from her mother and the Alexander S. Onassis Public Benefit Foundation, named for the late son, which controls the shipping business and a vast charitable trust.

Roussel and the foundation have fought bitterly in the courts, trading charges of mismanagement, embezzlement and defamation. Roussel even accused the foundation’s Greek trustees of plotting to kidnap his daughter.

Athina was not directly dragged into the fray. But, for many Greeks, she was conspicuous by her absence. Her visits to Greece have been brief and infrequent — the last in 1999.

“I want to forget the name Onassis,” she told the Italian magazine Oggi in 1998. “It’s the cause of all the problems.”

Athina Roussel, granddaughter of the late shipping tycoon Aristotle Onassis, will inherit half of the family fortune when she turns 18 Wednesday. She's shown here with her father, Thierry Roussel, in March 1998.

But it’s also the source of her dazzling wealth that reportedly includes gold, art masterpieces, property in France, England, Switzerland and Argentina and the private Greek island retreat of Skorpios, where the family’s “Pink Villa” was lavishly decorated by Jacqueline Kennedy Onassis, the former American first lady and second wife of the shipping tycoon.

On her birthday, Athina plans to meet with Swiss authorities and KPMG Fides auditors, who have overseen the estate since 1999.

At that time, the inheritance “officially will be passed into her hands,” said Alexis Mantheakis, the former Roussel family spokesman and author of a book on Athina. “It will be a bureaucratic thing, telling her what she has … this will take awhile to wind down.”

Fun-loving but cautious

Snippets of Athina’s life have appeared in the tabloid press — most notably her horse-riding and her reported romance with Alvaro de Miranda Neto, a Brazilian Olympic equestrian medalist who is 29 and has a child with his longtime companion.

The rumors of the relationship “haven’t been denied by the family,” Mantheakis said.

He said Athina, a brunette who resembles her late mother, was fun-loving in private but “very reserved, cautious of herself” in public. She is widely regarded as having had an ordinary upbringing.

Her next dynastic milestone will be her 21st birthday when she could take the reins of the foundation that controls the other half of the Onassis empire, valued at about $1 billion.

That’s not a certainty, however. The foundation’s board has indicated it might oppose her taking over the organization’s presidency.