For My Friend the Mirror by Treesa Cope (http://ywp.nanowrimo.org/user/881818).
Attribution: Cover design by Starflower Hunting. Stock image courtesy of ~LynnWest-Stock on deviantART (http://lynnwest-stock.deviantart.com/).
Christina is the name & book covers are the game. I'm also a poet, high school student, & ghost.