Who is Elizabeth from Reckless and what is their importance?

Elizabeth is a friend of Jeremiah's from St. Lucius. She appears late in the narrative during the Trustee Weekend party, and because she is unfamiliar to everyone, she is believed to be a teacher, leading everyone to hide any evidence of the party from her. Elizabeth eventually reveals herself to be a a party girl, her independent-mindedness appealing to the buttoned down Brandon in a big way. On the other hand, her previous sexual experience with Jeremiah, when Jeremiah had told Jenny that he is a virgin, creates difficulties in their relationship and, in turn, can be seen as a manifestation of the narrative's thematic interest in the tension between secrets and honesty.