"Mildew? Only you could equate mildew to humanity's pitfalls." River tries for nonchalant again and yes, she's rolling her eyes at him. It was better not to show few or apprehension when he approached. He already knew she wasn't pure human, but some kind of crazy mix between human and Time Lord. "I fail to see what this has to do with the situation at hand."

Something flashes in her eyes, a sudden terrifying thought of what he was about to do to her. But would he dare? Surely the Master of all people knew the importance of secrecy?