Washington (AFP) - In 2008, Michelle Obama was tentative on the campaign trail, wary of saying anything to jeopardize her husband's historic bid to be America's first black president.
Eight years later, the self-assured first lady -- back on the campaign trail -- electrified Democratic Party faithful with a passionate takedown of Donald Trump and what she called his "frightening" attitude towards women.
"It has shaken me to my core in a way that I couldn't have predicted," Obama told a rally for Hillary Clinton in New Hampshire.
"This is not normal. This is not politics as usual. This is disgraceful. It is intolerable."
The speech cemented the transformation of Obama, who turns 53 on Tuesday.
Once a reluctant 'mom-in-chief,' the tall, toned Princeton and Harvard graduate -- America's first black first lady -- has evolved, becoming a singular voice for women and a political dynamo.
During her husband's two terms in the nation's highest office, the native of Chicago's South Side -- who grew up in a one-bedroom apartment with her parents and older brother -- has also become a style icon and global role model.
"One of the most intriguing things about Michelle Obama is that she represents so many things to so many different people," Peter Slevin, a professor at Northwestern University's Medill School of Journalism and the author of "Michelle Obama: A Life," told AFP.
"She chose her issues, she stayed true to her values and she made the role uniquely her own."
- From the South Side to Harvard -
Michelle LaVaughn Robinson was born in Chicago on January 17, 1964 to a stay-at-home mom and a father who never missed work at a city water plant despite a battle with multiple sclerosis.
She received an Ivy League education at two of the nation's most elite schools -- Princeton and Harvard, where she studied law, as her future husband would also do.
Michelle joined the Sidley Austin law firm in Chicago upon graduation and it was there that she met Barack Obama -- a young associate she was asked to mentor.
That meeting would change her life. Obama's political career skyrocketed, and by January 2009, their family would move into the White House.
- Her causes -
At first, Michelle Obama focused her attention on getting the couple's two young daughters, Malia and Sasha, settled into their new home.
"Those early years in the White House were a real adjustment for Michelle," David Axelrod, a former senior advisor to Barack Obama, told CNN.
"She had to start over in so many ways and she had to do it under the watchful eye of the world. And that's a lot of pressure."
The first lady soon found her stride, and steered clear of controversy, embracing causes with universal appeal.
Her "Let's Move" initiative to stamp out childhood obesity through healthy eating and exercise earned praise, as did her work to promote the wellbeing of military families.
Jennifer Lawless, the director of the Women and Politics Institute at American University in Washington, told AFP the "strong argument she made for being active... resonated in a way that a lot of first ladies' issues don't hit home."
In 2015, Obama went global with the "Let Girls Learn" campaign, a cross-agency effort to improve education for teenage girls worldwide.
"She connected powerfully with a wide array of audiences -- as a working mother, as a progressive Democrat and, as she herself put it, as a 'little black girl from the South Side of Chicago'," Slevin noted.
Throughout her time at the White House, Obama has also emerged as a beacon of support for the US fashion industry.
She turned once little-known designers such as Jason Wu into major style stars, and made it acceptable to wear a cardigan to meet Queen Elizabeth II.
And she embraced social media and pop culture -- dancing with late night talk show host Jimmy Fallon, rapping with Missy Elliott in a "Carpool Karaoke" sketch, or doing the mannequin challenge with NBA superstar LeBron James.
"She's just fundamentally cool. She is comfortable in any kind of setting. She seems real," Lawless said, adding that her television appearances or viral videos did not seem "artificial -- just her embracing the way people communicate."
- Political force -
Last year, as Clinton and Trump vied for the presidency, Obama took on a new and somewhat unexpected role: political powerhouse.
She was a natural on the campaign trail and a forceful surrogate for Clinton, herself a former first lady.
In October, Obama -- a first lady who once shied away from controversy and endured racial slurs throughout her time in Washington from a small fringe of Americans -- unleashed a fierce attack on Clinton's Republican rival.
"This was a powerful individual speaking freely and openly about sexually predatory behavior. And actually bragging about kissing and groping women," she said of Trump's comments caught on video, which he dismissed as guy talk.
"The men in my life do not talk about women like this," she said. "This is not how decent human beings behave."
That day, Obama knowingly stepped into the political limelight she had long shunned -- and people listened.
"She spent eight years developing a relationship with the American people and they came to trust her," Lawless told AFP.
- Moving on -
In an exit interview with CBS, the president admitted his wife was looking forward to regaining some semblance of a normal life.
"Michelle never fully took to the scrutiny," he said. "She never fully embraced being in the public spotlight -- which is ironic, given how good she is."
Obama has repeatedly said she is not interested in a political career for herself, but could she follow in Clinton's footsteps, from the role of first lady to elected office?
"In 12 years, if an Illinois senate seat is open and the Democrats have no one to run... who knows what can happen? Life changes and she's young," Lawless said.