Guardian of Fate — L.J. Kentowski

Saving souls for the Angels can wreak havoc on a girl's social life, but Cassandra Cosgrove has learned to manage. That is, until her visions suddenly become unpredictable and she finds herself surrounded by secrets. It turns out, a sparse social life is the least of her problems. Thrown into a world of danger, with her own soul on the line, Cassandra is forced to put her life in the hands of a dark, mysterious stranger who claims to be the only one that can save her. But how can she trust the man she's dreamt of for years, especially when those dreams centered around one important warning - he was there to kill her. In order to survive the evil that threatens to destroy her, Cassandra must learn who to trust, but more importantly, she must discover who she really is.