Blade of Fire (The Icemark Chronicles 2)

Blade of Fire (The Icemark Chronicles 2) by Hill, Stuart. paperback edition. ISBN: 9780439873277.

Many years have passed since Queen Thirrin and her allies defended the Icemark against a brutal invasion. But now General Bellorum is back, along with his bloodthirsty spawn--twin sons even more vicious than him. Thirrin and Oskan also have a family: two girls and three boys. But darkness lurks within the House of Lindenshield: Medea, the couples cold-hearted fifteen-year-old daughter, is just coming into her magical powers, and she may be the downfall of the kingdom. Its up to her brother, Charlemagne, crippled by polio as a child, to return from exile and rescue the land he loves.