When it premiered in September, The CW’s “The Vampire Diaries” drew the largest audience of any other premiere since the network’s 2006 debut, and it has maintained impressive momentum ever since.  On the heels of a 2010 People’s Choice Award for Favorite New TV Drama, the show returns tonight after a nine-week hiatus.

“Degrassi: The Next Generation” alum Nina Dobrev, who recently celebrated her 21st birthday, is pulling double duty. She not only stars as the show’s magnetic ingenue, Elena Gilbert, but also as her civil-war-era doppelgänger, the bloodthirsty vampiress Katherine Pierce.

The fall finale left us with a shocking cliffhanger. Elena, having discovered the disturbing truth about her resemblance to Katherine, stormed out of Stefan’s bedroom — only to get into a car wreck with a mysterious supernatural creature while driving through the woods.

Despite the demands of playing two characters, Nina made time to chat with me about her favorite episode, Elena’s post-car-accident dilemma, and which of her castmates served as inspiration for Katherine’s devil-may-care attitude.

Congratulations on all the success! To win something like a People’s Choice Award, that’s voted on by fans, must be incredibly gratifying.

We felt so good to be nominated, but you never really expect to win, and then they didn’t fly any of us out there, so we just assumed that we didn’t win it. We wrapped for the day in Atlanta and went out to dinner, a couple of us, and we got a text message that we won and we all kind of freaked out, like, “What? Really? Are you serious?” It was very cool.