Castle: (while reading the threatening letters) Considering what he's capable of, you would think Bracken would have more formidable enemies.
Beckett: Oh, obviously, you never saw the letter that I sent him.
Castle: No, I did, actually. I liked the way you, uh, dotted the "i" on "kill" with a little heart. It was a nice touch.
Beckett: Well, I was trying to give it a personal feel.
Castle: Well done.