There's a different kind of insistence in his gaze, different than the times he's begged her to let him work the siren or follow her into a potentially dangerous situation. It's the kind of insistence that says, I know how you feel about letting someone else keep an eye on things, but deal with it.

So she deals with it, her hand falling to her side.

"Fine. I'm too tired to argue."

And for some reason, as she crosses the living room to head down the hall to her room, she feels compelled to spin on one heel and add:

"But if I see that doorknob turn - I will have you know, Mr. Castle, that I sleep with a gun."

It's an empty threat, of course, given that he already knows what she sleeps with - or doesn't.