THE VAMPIRES OF ATHENS SERIES
A teen from New York studies abroad in Athens, Greece and becomes addicted to the bite of a vampire, which gives her temporary powers. After falling for a demigod, she unwittingly becomes a catalyst to war between the vampires, who want freedom at any cost, and demigods, who want only to protect the city.
This is a clean young adult series. It's complete with three books, though a prequel is forthcoming.
PG 13: Violence, mild language, and no sex.