Oh, they're both just as ruthless, and just as caring, it's just a matter of how thinly that caring is spread. Also, while they both want to become human again, Whisper has become desperate. Unlike her husband, she cannot interact with anything physically, and her husband cannot feel anything physically. It makes her feel guilty, asking him to be her hands, and you see her at her worst here. She'll take time to reflect on it later in the series.
She isn't a bitch, she's determined. She doesn't care if it was Kei or Elder who turned them into monsters, she just knows Kei is the one they need to capture to be turned back, and she isn't as concerned as Overgrowth about who she has to knock over to get to that goal.
Unbeknownst to her, she's been internalizing Elder's own morality since the day they were created.
Page 3.
