Katherine's return may have been the highlight of the season one finale, but Vampire Diaries viewers should not forget about the transformation of Bonnie.

This character finally embraced her status as a witch and made it very clear to Stefan: don't mess with me. In an exclusive TV Fanatic interview, Katerina Graham talked about what's ahead for Bonnie on season two...

Talk about the concluding scene of "Fool Me Once."
That was a tough scene. They say art imitates life; it’s just a little theory. My grandmother had died that week and I had come from the funeral the day before that scene. I was a mess. Literally, it wasn’t Elena holding Bonnie, it was Nina holding Kat in that scene. I think that’s why it felt so real. Nina was the only person that I told, since I really didn’t want to be anywhere except with my mom. It was really tough, but I wanted to bring life to the writing and the heart of work of the cast and crew put it in. I’m glad people see that in it... It completely changed Bonnie and made her realize that if she had just said “no” from the beginning and stood up for herself that her grandmother might have still been alive, and that effects the rest of her choices when it comes to dealing with the vampires. Her resentment for taking away someone even though Damon just wanted Katherine, and it wasn’t specifically his fault, it was definite tied to it. If he hadn’t of made such a grave demand, everyone would still be alive.

Does season two push the bar even more than the first season?
Just the first episode alone raises the bar. It’s very, very rare in TV for the second season of any show to overtake the first one. But the first episode back just... I read it and I was shocked. This is my job, and I shouldn’t be shocked [laughs]. I read it just like a fan. When I get a new script I sit down and I can’t stop reading. It’s not a script to me, it’s an amazing story and I have to know what happens next...

People need to film themselves watching the Vampire Diaries first episode, and seeing their reactions. I would like nothing more than to see the fans YouTube their reactions and then talking about it. I’m dying to know what they think. Fans, Tweet me the link to your YouTube reaction!

In the trailer, we see Katherine and Bonnie in a very intense scene. Not a very nice way to greet her old friend's great granddaughter.
I think Bonnie is just standing in the way of everything to Katherine. Katherine is a bit heartless, so she doesn’t really care. Even though she was friends with Emily Bennett, I still don’t even trust that she wouldn’t screw Emily over to get what she wanted. Katherine gets what she wants and wants what she gets. She’s very heartless that way, so I’m not surprised that she’s that dangerous. It’s just, Bonnie not being able to tell the difference, I guess she figured it out a little late. She’ll get better at it in the future [laughs].

Is Bonnie as strong Emily yet?
I think in certain ways, Bonnie has the strength that her great grandmother had. I think Bonnie’s still got a long way to go before she’s really harnesses it and knows what to do in certain situations. She’s still learning. She’s not where she was last season. She’s definitely a lot stronger and knows who she is, which is an important first step. She’s still got a few more things to learn, which should be fun to watch.

The finale left off with Bonnie threatening Stefan. What is their relationship like going forward?
Bonnie’s priorities are ‘protect the ones of my own first.' That’s her thing right now. Protecting the people she loves, and if that is in any way compromised, in the least bit, she’s gonna come after you. With full vengeance. I definitely feel that from the jump, her relationship with Damon and Stefan is compromised because of everything they’ve put her through. It’s not going to get easier for them, but it’s also not going to get easier for Bonnie. She will eventually have to make a very strong decision, which will impact everyone's lives.

** For another Vampire Diaries exclusive, read our interview with Sara Canning.