The Sinuous Bargain of a Cowardly Prince (book one, The Shadowed Throne Chronicles)

Since birth, Prince Ramiel has cowered behind his half-brother's shadow, unbeknownst to the kingdom of Arioch. But with no legacy or reputation to uphold, he's grown rather comfortable with his anonymity. Unfortunately, his peaceful nonexistence ends when war kills the crown prince. Ramiel quickly discovers that only one person can fill the hole his brother left behind--and it might not be who he thinks. He suddenly has three months to prove himself to his father, King Azriel, before the coronation of a new crown prince. His worth depends on his ability to harness magic, so the king tasks him with enlisting a master who can train him to fight using this powerful and abundant resource. In his search for a teacher, he coincidentally meets Ether, a young female elf who passionately agrees to take him under her wing. The two must work together to prove Ramiel's value to the king. But in a war-torn world founded on thoughtless laws and dark magic, history has a habit of repeating itself... ***