Boreas Mun was a tracker out of Fort Rocayne hired by Stefan Skellen to hunt for Ciri in the area around the trade route from Maecht to Ebbing, Geso and Metinna. His skill was such that he was even said to be able to track fish through water. He even saved Skellen when the latter fell through the ice on Tarn Mira. During the Assault on Stygga castle, he showed Geralt how to get to the castle.
In the aftermath of the assault and the subsequent Treaty of Cintra, he flees Nilfgaard to the East, intending to reach Zerrikania or even Haakland. At the foot of the Elskerdeg Pass he meets with Sigismund Dijkstra and Isengrim Faoiltiarna, both fugitives for their own reason and the three of them form an unlikely travelling party, presumably leaving the territories of the Nilfgaard Empire and the Northern Kingdoms for good.