Scheming 'Sopranos' sister a hit with public

"She's so selfish," Aida Turturro says about her "Sopranos" character, Janice Soprano.

(CNN) -- Aida Turturro loves Janice Soprano. She just doesn't particularly like her.

"She's not someone who would be my friend in my life," Turturro says of her duplicitous yet oddly endearing character on HBO's "The Sopranos," which kicks off its long-awaited fourth season Sunday.

"She's so selfish. Janice thinks about Janice."

When mob boss Tony Soprano's absentee sister turned up in the second season of the acclaimed series, viewers may have figured they were meeting an actual law-abiding, level-headed family member.

But beneath Janice's West Coast ways and New Age aura was another scheming, deliciously complicated character, adding yet another rich layer to "The Sopranos."

"What I love about her is there's no boundaries for her, I say good or bad," she says in a phone interview from her hometown of New York City.

"I don't look at her like she's a bad girl. She just misunderstood sometime, she's a little troubled, she's a little dysfunctional. She's a survivor."

'It's just her personality'

MORE STORIES • Putting 'The Sopranos' on the couch  • Edie Falco: 'Sopranos,' Sayles, stage star    RESOURCES • EW.COM: 'The Sopranos': Preview, gallery, episode guide and more  • TIME.COM: 'The Sopranos': Back in business

When Turturro first signed on in the second year of "The Sopranos," it wasn't entirely clear how long Janice would be hanging around with her next of kin.

"They really didn't know where they were going to take her or who she was going to become or if she was going to stay," Turturro says. But the writers and producers evidently liked what she did with the character, and kept her in the fold.

As with many of the "Sopranos" characters, she suggests, viewers feel a connection to Janice.

"I can't tell you how many people tell me that they totally know someone just like me. All the time," she says. "It's just her personality. They don't know someone who killed their fiancé because he slapped her, but it's what goes behind it. There's different levels."

Advocacy

Turturro has begun using her heightened profile as an advocate for people living with rheumatoid arthritis, a painful, debilitating condition that she was diagnosed with at age 12.

She recently went public with her RA by announcing the launch of a nationwide awareness program, "Joint Effort Against Rheumatoid Arthritis," which is designed to motivate the 2.1 million people with the disease to seek more information about it.

"There are people who can't go to work, can't button their shirts, can't hold their grandchildren, can't get up in the morning, and they don't realize that there are treatments out there," she says.

That treatment helps Turturro, who has appeared in numerous feature films, endure the grueling "Sopranos" schedule.

"You get nine days to do a one-hour episode. An hour and a half movie you film for at least a month and a half, so you're talking time," she says. "It's hard."

After wrapping up filming on the fourth season earlier this summer, Turturro looks forward to beginning work on what could be the final "Sopranos" season.

"We definitely will film one more year starting in January, so we will have a year five," she says. "Do I think it's going over that? No, I don't think so."