Thread starter, you seem so confused by her being that you start fantasizing about what might lie "underneath that pretty looking exterior"... HALT!!
Do not fear! Embrace! (lolols, up til now your description of her does not sound dangerous...I agree with Quinlan's replies... don't worry bout it and get to know the girl.)
Hm...So...When I "flip" (this doesn't happen fast though) I focus on my goal and won't hold my thoughts back when people truly 'intrude on me'. I'll be more openly (and very easily) critical about ..well almost anything related to me then (you can call it: loudly broody & worried & also sad actually), and will only care about what needs to be done according to some picture drawn in my mind ('to make things better').
...'Usually, this will end up in me feeling guilty, confused and semi-crying (after the self-realization). ^^
So, don't worry 'bout it, she's not a demon ^^
My shadow is most prominent when I'm under a huge amount of stress. An especially cringe-worthy period was a few years ago when I was recovering from a horrible case of malaria. For a few weeks, I was blunt, judged every single thing around me quickly (and sometimes verbally) dismissing that which I deemed not worthy and had a vast desire to have my own way in every single scenario. I still shudder when I think about it.
And I believe you've deeply misunderstood the poor girl. I see no need to make her aware of how uncomfortable she makes you unless you're colleagues or close in some manner which you're apparently not especially when you're so vague about what it is. Seriously, her husky voice?