Natalie Portman is the anti-Lohan.

She's made the most seamless, least bumpy transition from child star to adult star since Jodie Foster. Her life has been remarkably free of tabloid drama and embarrassing personal scandals, just as her career has been free of embarrassing projects (slasher films, teen sex farces, Disney TV series) that mark the résumés of other stars her age. Yet only now, with the Dec. 3 release of 'Black Swan' and its attendant Oscar buzz, does the 29-year-old Portman finally seem poised to begin the series of adult roles that seems to have been her destiny ever since she made her debut at 13.

Throughout her 16-year career, Portman has seemed like a grown-up in the body of a girl. She's always seemed more mature than her age and petite physique would suggest, yet she's hardly managed to play a grown-up with adult feelings and responsibilities. Even in 'Black Swan,' she plays a character who's having a hard time navigating the transition between girlhood and adulthood, a young woman whose breakthrough into grown-up sexuality threatens to be both her salvation and her undoing. Portman is the child star who was never a child, and the grown-up star who's still not a grown-up.
From the beginning, when the 13-year-old debuted in 1994's 'The Professional,' Portman seemed unnervingly precocious. She was astonishingly poised as the nymphet who moves in with a grown man (albeit platonically), declares her love for him, and persuades him to teach her how to be an assassin in order to avenge her murdered family. She displayed similar aplomb in her next major role, in 'Beautiful Girls,' as a 13-year-old who convincingly enchants a thirtyish Timothy Hutton (who is just barely wise enough not to go all Humbert Humbert on her).

Natalie Portman in 'The Professional'

Over the next few years, her adolescent characters would discover sexual feelings, but they still weren't quite adults. Or were they? Her Ann August in 'Anywhere But Here' sometimes seems more mature than her flighty mother (Susan Sarandon), sometimes not. Her Novalee Nation in 'Where the Heart Is' is a pregnant teen who, even after becoming a mom, remains strikingly naive and innocent. And in the three 'Star Wars' movies she made between 1999 and 2005, she evolved from teenage monarch (and babysitter to the boy Anakin) to grown stateswoman -- and mature lover and wife to younger-man Anakin (Hayden Christensen, who in real life is two months older than Portman).

Natalie PortmanDuring the 'Star Wars' years, Portman famously managed to find time to earn a degree in psychology from Harvard, but her roles afterward continued to blur the line between girlhood and adulthood. She still seemed a teenager as the free-spirited pixie who bewitches Zach Braff in 'Garden State.' She was a soldier's widow who spends a sexless night with Jude Law in 'Cold Mountain.' 'Closer,' with its bitter plotlines of temptation and adultery, seemed like it might mark more adult turf, but even though Portman played a stripper in it (a curiously chaste one, who doesn't actually bare her flesh on screen), she still seemed like a kid. Not only was she much younger than costars Law, Julia Roberts and Clive Owen, but hers was also the character least affected by the betrayals all around her, and the one who got to walk away still cheerful, carefree, and unspoiled.

'V for Vendetta,' for all its grad-school seminar philosophizing on fascism and media manipulation, seemed an echo of Portman's first movie; as in 'The Professional,' she was a waif taken in by an emotionally scarred older man, who served as a platonic father figure and taught her how to be a killer. She played another pixie type in the kids' movie 'Mr. Magorium's Wonder Emporium.' She hinted at grown-up, bad-girl behavior in 'Natalie Raps,' a profane video she made for 'Saturday Night Live,' which was hilarious because her ongoing good-girl, Harvard scholar image made it seem completely implausible.

'Saturday Night Live' - 'Natalie Raps'

Portman's next roles hinted at a more adult sexuality with hype about their nudity. But 'Goya's Ghosts' used a body double, and 'Hotel Chevalier' (the prelude to 'The Darjeeling Limited') included a sex scene in which Portman was careful not to show any of her R-rated body parts.

The new 'Black Swan' also sees her poised between childhood princess fantasies and adult sexuality, though that's the point of the character. Her Nina Sayers is a ballerina who lands the role of the swan queen in 'Swan Lake,' but who has difficulty tapping into the wanton sexuality required to play the seductive black swan. Part of Nina's problem is professional discipline taken to obsessive extremes, but part is that she still lives with her controlling mom (a gargoyle-ish Barbara Hershey) and sleeps in a pink bedroom full of stuffed animals. Even as she's coming into her own, however, Nina sees the specter of her own mortality in the form of Beth (Winona Ryder), the former star ballerina who, at nearly 40, is considered an over-the-hill has-been. For the first time, the 29-year-old Portman looks worn and haggard. (The actress lost weight to the point of gauntness as part of her ballet training for the role, but there's also the character's crushing stress and anxiety.)

'Black Swan' Exclusive Clip

What liberates Nina's sexuality is the arrival of Lily (Mila Kunis), a rival ballerina whose bad-girl air and casualness of movement suggest she'd make an ideal black swan. Nina sees her at first as an enemy but comes to fantasize about her as both a lover and as the black swan within her own psyche. There's been a lot of hype about the movie's lesbian sex scene between real-life pals Portman and Kunis, but while it's a pivotal event in the plot, it's only one of many milestones along Nina's treacherous journey of evolution.

(By the way, in the already infamous scene, Portman convincingly displays the signals of sexual ecstasy, but she still doesn't display any naughty bits. Neither does Kunis. This discussion may sound like hairsplitting, but its Portman's refusal to go full frontal, while going up to the line, that allows her to maintain an image of classiness and purity.)

The role of Nina is earning Portman her first serious Oscar buzz since 'Closer' (the only role for which she has been nominated to date). Part of that has to do with the sexual politics of the Academy Awards -- the Oscars like to reward classy actresses who push the boundaries of sexual license -- but part has to do with the sheer rigor of the performance. The Academy may choose to reward her for taking on her most adult role yet, a role that hints at a future of fully mature characters for Portman. Or it may decide to honor her simply for playing a role that's extraordinarily difficult, one that dances along the border between girlishness and maturity just as she's done throughout her career. Maybe that will be her future, continuing to play roles that blur that line for a while longer. Eventually, however, whether she wants to or not, she'll have to grow up.

•Follow Gary Susman on Twitter @garysusman.

Related: Natalie Portman's 10 Best Movie Performances (So Far)
Black Swan
R 2010
Based on 42 critics

A ballerina's grip on reality begins to slip as her drive to succeed threatens to consume her. Read More