Collider has an interview with Ian Somerhalder.
Check it all out here.
Here is an excerpt:
Question: With Stefan having departed, what role will Damon have in Season 3? How will he change?
IAN SOMERHALDER:
Honestly, it’s a television show and these characters evolve. I would rather just remain the bad-ass dude that gets all the great lines and rips everybody’s heads off. That’s what I would prefer. I know it sounds a little sadistic, but it makes for a better character. But, I don’t think that’s the way life is. Kevin Williamson basically sat me down and said, “Just shut up and listen. Life is not one-dimensional. We change.” It’s that push-pull. He’s fighting against what he truly is, and that’s what makes the story dynamic. He is an anti-hero. He doesn’t know how to do all this stuff, so I think he’s going to have some trials and tribulations.
Ultimately, he’s not happy with the way things have turned out. He tried, for two seasons, to get his brother to do what he wanted him to do, which is to be what he is. He wants them to just eat and destroy everything in their paths. Now, Stefan is running around with a guy that Damon hates and tried to kill him. He’s effectively left Damon in this town with this girl who’s 150 years younger than he is, that he’s in love with, but can’t have because she doesn’t want him and it’s his brother’s girl. He’s just sitting there, thinking to himself, “This sucks!” But, I think he’s going to rise to the occasion. He’ll have the same grin on his face, if he’s ripping your head off or saving a kitten. He feels the same way about both things.