The Iron King by Julie Kagawa

Meghan Chase has a secret destiny - one she could never have imagined...

Something has always felt slightly off in Meghan's life, ever since her father disappeared before her eyes when she was six. She has never quite fit in at school...or at home.

When a dark stranger begins watching her from afar, and her prankster best friend becomes strangely protective of her, Meghan senses that everything she's known is about to change.
(From the YouTube description)