Hákon Hákonarson (Håkon Håkonsson) is the son of Hákon Sverrissonn (Håkon Sverresson), leader of the Birkibeinar faction in the ongoing civil war against the Baglarr. He is also the grandson of Sverrir Sigurðarson. Hákon Hákonarson is hunted down by the Baglarr as born in their territory and a threat to their effort to implement Church rule in Norway.
A group of Birkibeinar therefore flees with the boy in the winter of 1205/1206 to save him. Upon being stranded in a blizzard, two of the best Birkibeinar skiers, Torstein Skevla and Skjervald Skrukka, carry the heir to the throne over the mountains, from Lillehammer to Østerdalen, to the safety of King Ingi Bárðarson (Inge Bårdsson).
Hákon Hákonarson becomes King of Norway in 1217 and refuses to give allegiance to the Church. Hákon Hákonarson ends the civil war, builds a formidable naval fleet, and pursue and aggressive foreign policy. He brings Iceland under Norwegian rule and otherwise leads Norway through a period of relative peace and prosperity.
More complete (hi)story in Úlfheimr: The Tenth World and Úlfheimr: The Dark Age.