"Some woman I don't know?" he repeats, echoing her words and shifting is seat to lean forwards. "That's exactly what I want to know. Do I know her or should I watch my back whenever she's around?"

The two of them have figured out a sort of system with each other. Perhaps some of that resembles trust. But Cesare wants to make it very clear to her that if she does anything remotely suspicious, he won't take kindly to it.