The Prince of Fire
Loki is the child of tales long since assumed to be legends among the Jotuns. He is born with warm skin and eyes the color of fire, marking him as an extraordinarily powerful sorcerer-- one who can control both fire and frost. His distinguishing traits are hidden from all Jotuns in the realm, save for the royal family. He is nameless to the people of Jotunheimr, simply "the prince," lest his name ever expose him to the Asgardians.
Odin has fallen into the Odinsleep and Thor holds the throne in his absence. After Volstagg and Hogun are killed while trespassing on Jotun soil, Thor responds with an army to take back the casket, fearful of the Jotuns possessing such power. Thor goes searching for something to barter with in Jotunheimr.