Banshee
Banshee didn't fully understand what they were discussing right in front of her, but she could tell that Slade had said suggested something that Julian strongly disagreed with however after a significant look from Slade he'd begrudgingly consented. What exactly this agreement was in regards to she did not know, but the words "murder", "cold" and "blood" she recognized. Would they take her back to the lab and scientists she normally worked with? Would she complete her mission or had it been abandoned? However as he continued to speak (Slade liked to use a lot of words when he spoke, it seemed) she recognized "piano" as the thing that he had used to play the music as well as the word "song".
From what she'd gathered it was very possible that they would return her to the lab where she'd spent her life up to this point. I was also possible that she was going to be given the opportunity to execute her Target (though this was only, of course, if the Bad Music indicated that she was to kill him). However what Banshee thought was most likely to happen was that she would be removed from this cell and taken back to the room where the Prince had played the Good Music and drowned out the bad.
Deciding that this was the most favorable, and preferred, outcome Banshee started nodding excitedly. This was an obvious indicator for yes and she'd used it many times to respond to any simple "yes or no" questions, such as the ones occasionally directed at her back at the lab. "Music," she stated, excitement in her voice, "Please."