She backbites a lot.  Whenever I speak to her, she has something vicious to say about someone. 

Does she share these feelings because she considers me her friend?  Does she share them in confidence, knowing I won't tell anyone else?  Is she just being honest?  Does she just need to vent?  Does she just vent to me, or does she vent to everyone?

What's scarey is that she is so friendly with the people she criticizes.  Behind their backs, she's all venom and spite, but when they're face to face, she's all sweetness. 

It makes me wonder what she says about me when I'm not around.