Everyone has a past, Stefan. Mine needed to stay far, far away. But thanks to you, my plan nearly failed before it even began.
Once George told me that the roundup was imminent, I made sure I could see you one last time. But your father used your love for me against you. He poisoned your blood. We didn't have long. Then Damon, being Damon, nearly ruined everything.
I want what I want, Stefan. And I don't care what I have to do to get it. My list of victims is a long one, and I have no problem adding one more name to that list.
Stefan
Come on, Katherine. If you wanted Elena dead, you would have done it by now.
I still can. If I have to, I will snap her neck like a twig. And you know it.
[Pause]
I don't want you seeing Elena anymore. If you don't remove her from your life, I will kill everyone that she loves in her life while she watches,and then I will kill her while you watch.
(...)
I've missed you, Stefan. I just wanted to spend some quality time with you.
Yeah. No. I get it, okay? She's dangerous. But every day that we're together it's dangerous. Why are you giving her so much power over our relationship?
I told you I’d find a way to stop Katherine, didn't I? Well this is it. This is the only way because she’s stronger than me, and unless that changes, I can't protect you.
I know how you feel about helping us out, but since you’re the one that linked Mason with Katherine, we finally have an opportunity to get an upper hand on both of them, so just hear us out.
Mason Lockwood’s a werewolf. Katherine’s evil. They’re the bad guys. Really? You’re going to play morality police with me right now? Let me put it to you another way: they’re a threat to Elena. So you, witch, are going to get over yourself and help us.
Stefan
Yeah, he meant that as a question with a “please” on the end.