The Warrior Heir by Cinda Williams Chima

In this series everyone is born with one of five stones. With these stones they become wizards, enchanters, sorcerers, warriors, and one other I can't remember. Wizards are the ruling class and are divided into two main groups, the White Rose and Red Rose. The ruling group is determined by playing Warriors in tournaments and winner of the tournament gains power for the hosting group until the next tournament. Warriors have become very rare and are sought out by the wizards and stolen at a young age and trained to fight. Jack was born without a stone, but was suppose to have one. In order to save his life, a wizard inserts a Warrior stone into him so that her group can have a Warrior later. Jack's aunt who is an enchanter isn't too happy since he was suppose to be a Wizard, however, she bargains with the Wizard to allow Jack to stay with his family who were not born with stones and therefore are inconsequential to the wizarding world. Jack is forced to take 'medicine' every day for his 'heart' condition. One day Jack forgets to take his medicine and finds out that he has tons of energy and some interesting powers. Jack then starts training without the knowledge of the wizards and he is even able to use some wizarding powers that he was born with. By the end of the book, Jack is forced to fight in the tournament against another Warrior that has been training since birth whereas Jack has only been training for a couple of months.

This sort of reminded me a bit of the Hunger Games in the sense that young teens are raised to fight to the death for political power. It has the same feel/writing as books such as The City of Glass. I've enjoyed reading the first book and am in the process of starting the second book, The Wizard Heir.