Olsen was a Captain of the Witch Hunters. He led a cadre of Witch Hunters behind enemy lines during the fighting between the Lightists and the Hesperians at Ambermill and Port Ambermill. His mission was to assassinate as many magi as possible, and if possible, General Niccolo Marius as well.
Drawing twin swords, Olsen engaged Marius in battle, but Marius had the advantage of being on horseback, and managed to kill Olsen.