Guardians - T. J. Baer - Bog

Seventeen-year-old Alisha Howard is having a hard day.
She's had to rescue her headstrong little brother from getting eaten by a monster from another dimension, her mom has put her on dish duty as punishment for bringing her sword to the table (again), and her lifelong enemy, snarky rich girl Belladonna, is starting to look like both a real human being and someone Alisha would like to kiss.
Oh, and to make matters worse, it looks like the world is about to end.