Giants, said to have been a scourge of the sea, terrorizing the world in ancient times, are now being linked to ice, both through the Viking imagery and by having their legendary DF freeze opponents.
Lunarians, on the other hand, which WB said were treated as gods living atop the Red Line, are obviously designed around their iconic flame.
I wonder which came first: were the Lunarians worshipped because they could naturally oppose the giants' ice? Or did the giants seek out the ice DF to neutralize the Lunarians' flame?