I love how Pansy almost sounds affectionate when she calls Marietta "Sneak," yet eventually is willing to call her by her real name.
I love the teenage angst of this, but also how the two girls are drawn to one another by fascination instead of gooey crush (neither would be caught dead calling the other "dreamy"!).
And the way you describe the effects of that horrible night on Marietta--we don't really ever read anything about her own reactions to it, but yes, it sounds just awful, disorientating and terrifying. And then to be outcast and believe herself to blame, even though her very memory of what she did is gone...