Miss Mayhem by Rachel Hawkins
Several months have passed since Cotillion and Harper is working with Ryan and David to help figure our David's powers without getting him killed or making him crazy. The friends have decided to try dampening David's visions (without his knowledge) because the visions are so painful for him. This seems to work until one night when David has an extremely powerful vision that leads him to the headquarters of the Ephors (the people tasked with overseeing the Oracle and who up until recently wanted to kill David), a home which up until weeks ago had been a burned out wreck. At the house they meet Alexander, one of the Ephors who reveals to Harper that she is not technically a paladin yet. Alexander informs Harper she must go through a series of trials called the Peirasmos, and if she doesn't do them, then the Ephors will simply keep coming after her and Ryan until they are both dead and they can make a new mage and paladin. Also, she doesn't actually have a choice in wheth...