Good thing Chyler Leigh has a sense of humor.

Talking about McDreamy and McSteamy with her on the set, Will Keck of USA Today complimented Chyler on her real-life McDreamy - a handsome actor.

Which was nice, until his name was mentioned (Jason Behr of Roswell), and Chyler looked as if the reporter were from another planet.

Jason Behr, it turns out, is actually the husband of Private Practice actress KaDee Strickland (and the ex-boyfriend of Katherine Heigl, incidentally).

Fortunately, Leigh just laughed and talked about her love for actor Nathan West, her actual husband. Unfortunately, she wouldn't fill us in on who her character is going to hook up with this season. Stay tuned on that.

New faces are checking in to Seattle Grace to help fill recent vacancies. Veteran actor Edward Herrmann, 64, signs up for a few episodes as Norman, the world's oldest intern; someone from the past may be returning (we're not telling who); as well as Diahann Carroll, as Dr. Preston Burke's mom.

But the biggest staffing change is Chyler Leigh, 25, who plays a character with a familiar last name: Grey. Meredith's half-sister, Dr. Lexie Grey.

While having another Grey around naturally complicates life for Ellen Pompeo's character, cast members rave about the addition of Leigh.

"She's the sweetest, coolest, funniest chick," says Katherine Heigl (Izzie).

"I think she is one of those girls who is quiet, because it's her first season on the show. I imagine it's awkward and difficult to come in to a cast that has been here for years. But you spend a little one-on-one time with her, and she's hysterical."

Chyler Leigh has much to celebrate beyond landing a role on one of the hottest dramas on TV in Grey's Anatomy. It comes after some very rocky times.

Born in Charlotte and raised in Virginia Beach, her folks divorced when she was 12. She moved with her mother to Miami, where the mother remarried her first husband. Like Lexie Grey, she, too, has distant half-siblings.

She met her actor husband, Nathan West, on a TV pilot audition when she was 16 and he was 20. Once settled in Los Angeles, they began a two-year battle with drug addiction that nearly cost them their lives.

Her drug of choice from age 17 to 19?

"Everything," she confesses. "There are a lot of times we really shouldn't have survived. He and I have literally been through hell and back,"

Chyler Leigh places some blame on their "broken families."

"We went through about two years of complete obliteration. It came down to, 'Do you want to choose to live, or do you want to choose to die? And we chose life."

Leigh credits faith and a "really awesome church" with giving them "a reason to live." She no longer communicates with her mother and has seen her father only rarely over the past eight years.

Now, she and Nathan, who works at their non-denominational Christian church in between acting roles, "have so much to share with our kids."

They married when she was 20 and are now the parents of daughter Taelyn, 1, and son Noah Wild West, almost 4, whose potato-like drawing of his mother is pinned up on the wall of her on-set trailer.

T.R. Knight (George) remembers seeing Leigh on the short-lived 2005 series Reunion, where her character had to age from her teens to late 30s.

"What a class act," Knight says. "She seems incredibly well adjusted for an actor and makes me laugh a lot."

After Reunion's cancellation, Leigh and her family moved to Anchorage to stay with Nathan's mother. When a call came about a role on Grey's Anatomy, Leigh rented the show's second-season DVD from a store in the Alaskan city.

"We literally watched the whole season back to back over two days," she recalls. "Then we watched Season 3 online to catch up."

Soon after a meeting with series creator Shonda Rhimes, Leigh was offered the role of "Girl in Bar." When she filmed her scene with Patrick Dempsey, not even he knew who this mystery character would turn out to be.

Chyler Leigh didn't find out herself until just three days before filming her first episode. So how will Lexie get along with her big sis?

"Meredith thinks it's a bit strange that Lexie would even come to work at this hospital knowing she works here," says Ellen Pompeo. "It's awkward."

Pompeo, who has three older sisters and two brothers in real life, says that Lexie Grey's arrival will have a deep impact on Meredith. "She definitely has some issues and resentments she has to get over."

NOTE: To see a video interview with Chyler Leigh that accompanies this story, follow the above link to USA Today ...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.