Frostblood

Ruby is seventeen and a Fireblood, born with power over heat and flame. She has hidden it all her life from the Frostbloods, the ruling class, who are cruel to her kind. Then her mother is killed while protecting her, and Ruby's cover can no longer hold.

A group of rebel Frostbloods asks for her help in overthrowing their bloodthirsty king. Ruby, driven by a wish for revenge, agrees to leave hiding. Her abilities are unpredictable, and she trains with the rebels and with Arcus, who irritates her and attracts her in equal measure. He seems to see her as little more than a weapon.

The plan stalls before it begins. Ruby is captured and forced into the king's tournaments, where Fireblood prisoners are made to fight Frostblood champions. Her one chance to destroy the ruler who took everything from her is also a chance to avenge someone she has come to love.

This is a young adult fantasy with a romance running through it, built around the enmity between fire and ice. The pace is quick, moving from hiding to rebel training to arena combat. It is the first book of a series that continues with two further titles.