NEW YORK — Dr. Juliet Burke reveals herself to be a complex character on "Lost."

Or, rather, she reveals very little of herself. She is a combination of strength, cunning and wistful victimhood, all displayed on a face so enigmatic she could give the Mona Lisa a run for her money.

Introduced as one of the Others at the start of last season, Juliet has remained an object of delicious mystery, despite selective details parceled out by the show. Viewers still aren't sure where her loyalties lie — or even if they should dare to like her.

The only certainty: Elizabeth Mitchell does a bang-up job with the role, keeping viewers teased at arm's length even while drawing them in.

"I've had a tremendous amount of freedom to create something strange," Mitchell says happily.

Questions will probably multiply with tonight's episode, which is expected to give Juliet the spotlight.

Mitchell's rule of thumb in playing her: Don't act angry.

"She needed to be someone who could be a tremendous leader, who had an innate sense of power but didn't behave in an angry or strident way," Mitchell says.

The 37-year-old Mitchell grew up in Dallas, where, from childhood, she studied acting and performed in local theater, which helped her weather an uglyduckling adolescence.

"I was horribly awkward, tall and scrawny, with frizzy, crazy hair and terrible acne," recalls Mitchell, who is now an indisputable looker. "But it didn't matter even remotely on stage: There, no one's looking at your skin."

Mitchell began her TV career in 1994 on the daytime soap "Loving," and won acclaim four years later opposite Angelina Jolie in the HBO film "Gia." She had the title role in the 2000 TV film "The Linda McCartney Story," and played Mrs. Claus in the two "Santa Clause" sequels.

She had been a "Lost" devotee its first season. The next year, she steered clear of it.

"I was pregnant and I didn't watch anything that had any violence," she explains. So when she arrived in Hawai'i to begin shooting the third season, "I watched the whole second season in my trailer my first week. I really liked it. But I was shocked when those women (Ana Lucia and Libby, both gunned down without warning) got killed. That's probably where my fear of dying on the show began.

"But I found the work to be so exhilarating, I decided: Until they fire me, I'm gonna just make this all that I want it to be."

So far, so good.