The vampire looming over her is a lot stronger than she looks--and Krista isn't exactly the pinnacle of physical ability either--so her last attempts at struggle are completely futile. She tries to find the focus to make her magic work, but it's overshadowed with the realization of her own certain doom. She may have been spoiled with the last vampire she met, but she's not stupid. Feeling teeth at her neck is scary, but pretty much exactly what she'd expected.

She tries to make a sound of protest, she really does, but it doesn't work now that she's different and actually having to feel all those sharp teeth digging into her neck is so ephemerally horrifying and disgusting--but that's just the thing. Suddenly, shockingly, it's not anymore.

So it's probably a good thing she can't make much noise, otherwise this would be really embarrassing.