Once upon a time, there was a socialite called Nicole Richie, who, along with her legendary bestie Paris Hilton, was an LA nightclub fixture as famous for her bratty behaviour as she was for her drug arrests and A-list pals.

Then, one day, along came a Prince called Joel Madden... and we all know where the story goes from there.

Nicole's Angelina Jolie-esque transformation over the past 18 months, from Hollywood party girl into stay-at-home mum, has shocked a Hollywood most used to seeing her playing up onscreen in The Simple Life or being arrested for DUIs.

Ahlan! delves into Nicole's past and reveals how and why the ‘It' girl is so keen to transform her life and settle down...

Traumatic childhood
Taken in by Lionel Richie and his then-wife Brenda when she was two, Lionel first met his future daughter when she was playing the tambourine onstage at a Prince concert, and was reportedly being looked after by her (rumoured) biological father, percussionist Peter Escovedo. In 2005, Nicole denied he was her real father.

When she was three, the Richies put Nicole into therapy, and she saw a therapist until her teens. Formally adopted aged nine, Lionel and Brenda split soon afterwards, following Lionel's affair, and Nic revealed that their guilt meant her every whim was indulged - "Their way of making me happy was to say yes to everything I wanted, but I don't think a little girl should have that much freedom."

And now? Nicole is keen to create the stable, secure childhood and family life she never had with Joel, who she credits with saving her from herself, after he refused to be involved with her as she used to be.

"It would've been no question, because I didn't have time for that, at this stage in my life," the 28-year-old singer told her.

Hollywood bad girl
"It's been a pattern in my life - when I get in trouble, I try to get out of it, since I was little," Nicole revealed earlier this year. Arrested for alleged heroin possession in February 2003, she went to rehab to kick her drug habit later that year. Known as a Hollywood hellraiser, along with a gang that included Paris and Nicky Hilton, Brandon Davis and former wildchild, Bijou Phillips, Nicole's antics reached a wider audience in the first season of The Simple Life.

And her DUI arrest last December - during which she admitted she had "smoked marijuana that night" - brought home to the 26-year-old that she was lost in Tinseltown.

And now? "I really wasn't learning anything from that," Nic admitted. "So I kept making bad decisions or mistake after mistake after mistake. And I wasn't growing. I wasn't going anywhere." Adding of her brief incarceration, "This is my way of paying my dues and taking responsibility and being an adult."