On tour to promote her books, she struck many interviewers as a reluctant subject.
"She got that horror of the press from me," her mother wrote in a note that Sorenson quoted in his recent memoirs, Counselor. "She used to put her hands over her face when she saw cameramen."
Not any more.
After writing an op-ed piece for The New York Times declaring that Obama would be "a president like my father," Kennedy hit the hustings for her candidate, speaking at venues ranging from a small college in Pennsylvania to a big stage in Los Angeles.
"This is a bit unusual for me because I generally don't get involved in politics," Kennedy said in Austin, at one of the many Obama rallies she headlined.
Occasionally, she showed flashes of her father's famous self-deprecating wit.
"This is a big day for me because I get to introduce somebody who is not my Uncle Teddy," Kennedy said, flashing the familiar family grin, as she prepared to bring Oprah Winfrey to the stage at a February rally for Obama in Los Angeles.
Kennedy's endorsement of Obama in January — carefully choreographed for maximum impact with the one her uncle delivered a day later — put her at odds with her own senator, Clinton, and with some of her cousins. Kathleen Kennedy Townsend, a former lieutenant governor of Maryland, Robert Kennedy Jr., an environmental lawyer, and Kerry Kennedy, a human rights activist, all backed Clinton in the primary.
But the backing of the former president's only living brother and daughter provided a direct link to the White House that her mother had so famously and romantically nicknamed.
"Camelot Crowns Obama," read the caption on the TV screen as the former first daughter and her beloved "Uncle Teddy" appeared on ABC to discuss their endorsements.
Upholding the family name
While Kennedy has always shared her mother's desire to avoid prying eyes — she wrote one of her legal books about the right to privacy — she has also grown into a keen appreciation of her political birthright.
"Caroline is the keeper of the family flame," Sorenson writes in his memoirs.
He recounts a visit she paid him in 1974, when she was researching a high school paper on her father's foreign policy. The teenager at first relished the project but "it really became traumatic for her," her mother said in a thank-you note to Sorenson, which he included in his book.
"The more she read, the more it made her miss her father," Onassis wrote.
Kennedy has maintained her interest in her father's legacy.
Seigenthaler describes her as "deeply involved" in his presidential library.
She's president of the John F. Kennedy Library Foundation and helps select the winner of the award named for her father's book about senators who risk their political careers to stake a stand on principle.
In a 2002 interview she did while promoting Profiles in Courage for Our Time, a book of essays about some of the award winners, Kennedy did not close the door on a run for public office.
"I don't have any plans to do that right now," she said. "I don't plan ahead. My kids are young."
Now that they are older, "I would hope that she becomes increasingly involved on the national stage," Klein says. The New York schools chief, whose wife attended Harvard with Kennedy, sees her role with the Obama campaign as "part of her evolution."
Paul Kirk, a former national Democratic Party chairman who serves with Kennedy on the her father's library board, thinks that her preference to stay out of the limelight may be giving way to her desire to make a difference.
"You can't ring a bell quietly," Kirk says. "She realizes she bears some responsibility to keep the legacy going."