Oh, I don't think she always acts rightly--but then, who does? I'm probably giving the writers way too much credit, but I see her arc this season as her desperately trying to figure out the nature of her powers without having anyone to guide her. She's basically the epitome of the worldview shift on the show. She had this power pop into her life out of the blue, and then it kills her grandmother. So she has no one to help her figure it out. Meanwhile, one best friend has totally embraced the evil vampires (or at least that's the way it's got to seem) and the other has turned into an evil vampire. And then there's still more evil vampires who are coming to kill everyone she loves. And she's a super loyal friend, so she feel she has to do whatever it takes to protect them. Of course she makes bad choices sometimes, and I don't think that what she did to Luka was right in any way. But she's a 17-year-old girl whose life has been totally turned upside down. The way she behaves makes sense to me, even when I disagree with her.

There is so much more than could have done with Damon. I honestly feel like the writers have been half-asleep this season and the random plotlines we get have been like the random jerky movements a person makes when he's sleeping. Haphazad, not conscious and we're just waiting to wake up.

I totally agree.