Red Queen by Victoria Aveyard
Mare Barrow, of lowly red blood, is given a job in the royal palace to serve those with silver blood and supernatural powers. One day in front of the king, Mare discovers she has her own unique power. The king tries to hide this fact by calling Mare a lost Silver princess and betrothing her to one of his sons. In spite of this, Mare risks everything to help the Scarlet Guard, a rebellion against the Silver elite, and puts herself in grave danger.
Review from School Library Journal:
Seventeen-year-old Mare Barrow lives in a world where one's lot in life is determined by the color of one's blood. She was born a Red and has to make a living by pickpocketing and trying to dodge "the conscription" and being sent off to fight an ongoing war. Mare's resigned herself to the fact that she'll always serve the Silver, a genetically gifted group of people with supernatural abilities. A chance encounter with the prince causes Mare to suddenly find herself at the royal palace as a servant, where she discovers in front of everyone that she also has a unique gift. She is Red and Silver, and could be just the spark the Reds need to rise up against the oppressive Silvers. The king and queen quickly cover up Mare's anomaly by presenting her to the rest of the Silvers as a long-lost princess and betroth her to their second-born son. Now Mare is torn between playing the part of a Silver, and helping out the Scarlet Guard rebellion. The story has touches of the usual dystopian suspects. However, it's formulaic elements are far outweighed by the breakneck pace and engaging characters. There's a bit of teen romance, but luckily the characters are self-aware enough to realize its frivolity among the story's more important plot points. A solid debut from Aveyard and a welcome addition to the plethora of speculative teen lit.