The glint in her eyes was the sort of sign Horrible looked for to keep him going on his mission against good. It reaffirmed his purpose and after she spoke, he plucked up the courage to speak too. It was like they were of the same mind, while in reality they harmonizing.
"I cannot believe my eyes. How the world’s filled with filth and lies. But it’s plain to see the darkness inside of me is on the rise."
She had a nice voice. Billy would have said something had he realized they were singing.