Books in the The Banished Isle Quartet series

When the king of Iverastra is taken for ransom at the hands of the great wizard Melorvine, his subjects are forced to give up the very artifact he'd fought to protect: the Togan Eye stone. Now, their fate rests with Daerem, the king's sworn protector. A man of few friends and even fewer words, his shadowed past may hold the greatest danger of all