Originally posted by jonnin:

sutur (sp?) is a major enemy, and of the firey areas. Giants were often tied to ice and could be a major force as well. Fire and ice are seen as competing equals... Its a tossup, and whatever the devs choose is likely to be OK lore wise....

Actually the devs deviated from Norse Mythology here. One of the runestones state that Surtr has been long dead and the Surtlings have spawned from his remains.