Son of the Dawn by Cassandra Clare

The Lightwoods, the Shadowhunters who run the New York Institute, are expecting a new addition to their family: the orphaned son of their father’s friend, Jace Wayland. Alec and Isabelle aren’t too sure they want a new brother, and their parents are not assuaging their fears, too occupied with the dark news that Raphael Santiago, second-in-command of the New York vampire clan, has brought from the Shadow Market.