Lauren of course can't hear the chameleons thoughts. What he can do, however, is speak with animals. He murmurs a few words, an incantation, and though Sherlock could understand him before, now Lauren is actually expecting the chameleon to understand him and answer.

"Do you know why you have a note?"

The rat squeaks again, and Lauren looks briefly annoyed.

"I'm not asking you Stella, I'm asking the chameleon."

Jeez, what a noisy know-it-all she was.