Kate Beckett: Look, I signed up for this when I put that badge on. You didn't. It's not your fight.
Richard Castle: The hell it isn't. I don't hang around you just to annoy you. I don't ride out to murder scenes in the middle of the night to satisfy some morbid curiosity. If that's all this was, I-I would've quit a long time ago.
Kate Beckett: Well, then, why do you keep coming back, Rick?
Kate Beckett: Look, I may not have a badge... unless you count the chocolate one Alexis gave me for my birthday... But I'll tell you this, like it or not, I'm your plucky sidekick.
Kate Beckett: Plucky sidekick always gets killed.
Richard Castle: Partner, then.