In two separate interviews, The Vampire Diaries‘ Nina Dobrev and Paul Wesley discuss Elena/Katherine and Stefan respectively, talking about their journeys so far and what it’s like playing the characters.

Speaking to Assignment X, Wesley talks about Stefan’s transformation in season 3 to the ‘bad’ vampire, saying:

I want to play a variety of different characters in my life, and I didn’t want to be stereotyped, so it’s a great opportunity for me to do something different. I told [series producers] Julie [Plec] and Kevin [Williamson], “Look, I’d really love to do something [different],” and they said, “Great,” and they agreed. We don’t want anything to be redundant – we want to keep it fresh for the viewers.

Separately, Nina Dobrev has spoken to the New York Times about playing dual characters, and her commitment to the series:

I love playing Elena and Katherine, and it’s been a juggling act more than anything. […] So it’s been more about learning to manage time and learning when to let go. I’m a perfectionist, I put 110 percent into everything. Trying to do that for two characters, I’ve been putting in 220 percent. It’s been a lot of work, but really cool. It confused me sometimes, early on, and I learned, when you’re doing something like this 10 months a year for possibly six years, you have to preserve your energy.

She also teases the upcoming power shift on the show:

The power has changed, and the leverage is in different places. Klaus, instead of being the ruler and kind of the dictator, is now at the mercy of Stefan. Stefan has what Klaus wants, and he has to do what Stefan wants. [And] it’s not just that Klaus will do what Stefan wants, it’s that he’ll do so willingly. He’ll put up a fight, but Stefan has Klaus’ family, and at the end of the day family is the absolute most important thing, before friends, before the person you love. It’s a theme of the show, because of the vampires, but blood is what matters most.

The Vampire Diaries returns next Thursday at 8/7c on The CW!