The interrogation scene was interesting, in that it was so different from how Nick usually handles things. In five years he's raised his voice, what, a couple times? It was chilling to see him losing it like that. Even though I knew he was going to, that scene still left me stunned.
On the other hand, the restrained emotion in the breakfast scene was the more typical Nicky angst we're used to. When Sara said it was like he was going to rescue a person, not recover a body, I love how Nick looked down and kinda nodded before she even finished her sentence, as if he'd seen it coming and had been bracing himself for it all along. This episode was a great example of how Nick deals with personal trauma: he just pushes it back and sorta channels the emotion into his work. He only referred to his kidnapping when he had to, and even then he spoke about it in an almost casual way. I thought Sara looked like she had been hoping he would bring it up, so she could talk to him about it, but when she did, he steered the conversation back to the case. And it was the same after the interrogation. Even though Nick held others at arm length regarding the kidnapping, he did it so subtly that it almost didn't feel like he was blowing them off, and yet firm enough to make it hard for the others to broach the subject. It's really a dangerous way of dealing. I hate to think what would've happened to him if the little girl was dead.
Like others said, Nick showed extremely admirable judgement staying behind after that and basically let Sara run with the investigation - the kind of judgement we almost
never see from the others.
And I swear I literally melt into a puddle when Nick smiled at Cassie and called her "sweetie" in his sweet, sweet voice. Sigh.