When she leans in to kiss his cheek, Castle catches the faint stamp of gunpowder. He knows she must've washed her hands at least twenty times at the precinct, but the smell stains skin and it brings it all back to him in a hard, smoky memory. Castle hasn't had to do many brave things in his life, so when he sees them in other people, it's a sobering reminder of his own shortcomings. Beckett might be the bravest person he knows.

He slides his elbow from her grip and wraps both arms around her, pulling her in for a tight hug. "I'm so sorry," he says.