Castle, Season 2

Beckett:
Ten years since we came home and found that detective waiting for us. Ten years since we crossed that yellow tape and went into that alley. And every time I cross the tape at a crime scene, I think of that night.

Castle:
That's what makes you such a good cop.

Beckett:
What if I let her down?

Castle:
Do you know why I chose you as my inspiration for Nikki Heat?

Beckett:
No. Why?

Castle:
Because you're tall. [Beckett smiles and relaxes] Now go in there and do your job.