Sarah Rees Brennan 
Demon’s Covenant [EPUB ebook] 

Mae has always thought of herself as in control, but in the last few weeks her life has radically changed. Shes learned that her brother Jamie has magical powersand Gerald, the new leader of the Obsidian Circle, is trying to persuade Jamie to join the magicians. Even worse Jamie hasnt told Mae a thing about any of it.Mae turns to brothers Nick and Alan to help her rescue Jamie, but they are in danger from Gerald themselves because he wants to steal Nicks powers. Will Mae be able to find a way to save them all from the power-hungry magicians devious trap?