I have been missin a few forum discussions lately, so forgive me if it has been mentioned elsewhere: in the last WND you guys discuss possible motives behind the decision
Scratch made of keeping Lizzie safe. I did not hear you mention the following possibility:
during the first reading live, the lovely Jenna said during the Q&A session that we would discover something about the past of not-so-lovely Scratch which will paint her in a different way. She also mentioned, when you had her interviewed on WND, that she could not deliver a certain (unknown to us) line until KC told her something about Scratch and then she got it right immediately.
I think there is the possibility that Scratch had a miscarriage in the past, or was raped or had some kind of brutal experience in that "area", and upon walking in on
Tardust trying to rape Lizzie this past experience flashed on her, she felt sympathetic with Lizzie and intervened - in a brutal way according to her nature- to prevent it from happening. This would be the only thing resembling a human gesture from her ever in the series, as even with
Angel she was maternal and caring only to extract information from him, and she would never admit to it, but it makes sense to me. In this hypothesis, the line Jenna had to deliver many times before KC told her that certain something was the "You're sick..." line.