After injuring Ocarina and Flute in volume 23, Kuro Sizer laughs like a madwoman and flies away towards Hameln. Hamel and his companions come across her again there, when she swoops in to butcher a village that they've stopped at. Raiel tries to call out to the real Sizer within, despite the fact that no trace of her exists in that body anymore. Kuro Sizer does pause momentarily once when Raiel tries to reason with her, but any hope he has of reaching out to a trace of the real Sizer is shattered when Kuro Sizer replies that she's gonna fucking kill him. (This is the only time she speaks.)
Although Lute, during his possession by Bass, does have occasions where he can regain small control (whether it's just crying or even sealing Drum briefly so that Hamel can defeat him) I believe this is just due to his extremely high Holy Magic skills and possibly close proximity to his soul. I'm convinced that there isn't even a trace of the real Sizer within Kuro Sizer's body, and no amount of pleading would produce any sort of non-Vocal emotion in her. She could kill any of them without even pausing in her psychotic laughter, and she certainly doesn't show any trace of Sizer while she's busy slicing them up.
Because Kuro Sizer's existence is dependant on Vocal, the source of her animation, when he is greatly weakened and starts to splinter away the same things start to happen to her. She first loses her left arm when Raiel grabs onto it at the end of v27, and then her left leg crumbles away too during v28. Although this caused Vocal great amounts of pain (or even just 'pain', as he's probably not used to ever feeling it) Kuro Sizer isn't bothered at all by the loss of these limbs, aside from mild surprise when suddenly she finds she can't stand up anymore. However, she does cry out in pain when she's captured and chained up Guitar and he plunges the Daimaou sword into her thigh. I'm not entirely sure what to make of that. =S Either it becomes painful because it's the Daimaou sword, with her body's original soul within, or having limbs crumble away isn't actually very painful at all, and Vocal's just a total baby when he does actually experience it. XD I am kind of going with the latter. (There's also a chance of course that it's something not very well thought out by Watanabe, but that's not as much fun.)
The only way to ever bring Sizer back is to return her soul to her body, and Guitar gleefully shows off the Daimaou sword, complete with the jewel that has Sizer's soul trapped within. After receiving even further injuries (as if Sizer's scythe being plunged into and through him several times wasn't bad enough) he eventually manages to take the jewel from the sword, and return Sizer's soul to her body.
