This page is about Loki from Norse Mythology, not Loki
from Marvel Comics.
Loki is one of several powerful beings from the magical realm of Asgard, who have been worshipped as gods. Odin, once the ruler of the Asgardian gods, led his subjects in a war against their enemy, the frost giants from the land of Jotunheim (one of the nine worlds of Asgard). Laufey, king of the frost giants, was slain in battle and the giants were defeated. Surveying the spoils of war, the Asgardians discovered a small Asgardian god-sized baby hidden at the giants' main fortress. The infant was Loki, whom Laufey had kept hidden due to his shame over his son's diminutive size. Odin remembered his father Bors dying words to adopt the son of a father killed by his hands; Odin adopted Loki into his own family, raising Loki like a son along with his biological son, Thor. His birthday is December 9.
In childhood Loki greatly resented the fact that Odin and the other Asgardians favored the young Thor, who already had a nobility of spirit and excelled in all his endeavors. As a boy Loki began studying the arts of sorcery, for which he had a natural affinity. He became infamous for his mischievousness, but secretly resented Thor and the love that Odin lavished upon him. When Odin was preparing his greatest gift for Thor, the enchanted hammer Mjolnir, Loki interfered with its creation, causing its handle to be forged too short. Loki was envious that Thor would one day wield Mjolnir, and over the years repeatedly crafted schemes to make Mjolnirs power his own.
When Loki and Thor were still young, Thor was attracted to the swordmaiden Sif, who had beautiful gold-colored hair. Loki cut off her hair while she slept, but Thor guessed that Loki was responsible and demanded that he restore it. Loki enlisted the dwarves Brokk and Eitri to forge new hair for her, but as he did not pay them anything, they decided to craft the hair from nothing, making black hair from the night itself. However, Thor still loved Sif, even without her golden hair.
Thor and Loki occasionally adventured together as teenagers, though the competitive Loki always searched for an advantage over his brother. In his youth, he was more apt to aid his Asgardian family. When Loki learned that the sorceress Karnilla (queen of the magical beings called the Norns) was planning an attack on Asgard, he refused an offer to join her and instead alerted his fellow Asgardians to her scheme. Later on, Loki and Karnilla became occasional allies, although her love for the Asgardian Balder (an enemy of Loki) prevented her from aiding Loki in any way that would hurt her beloved.