Loki Laufeyson is the Trickster God, God of Mischief, Evil, and Lies a member of the monstrous Frost Giants of Jotunheim but was adopted and raised among the Asgardians a group of humanoid beings from the pocket dimension of Asgard, the Realm Eternal. Born smaller then the rest of his race and rejected by his father Laufey, he was adopted by the All-Father; Odin following the war. He was taken back to Asgard to be raised alongside his adopted brother Thor. He was worshiped by the humans known as Vikings and became part of Norse Mythology. Loki grew jealous of his brother after learning his true origin and schemed against him and Asgard. His later cosmic meddling led to the formation of the Avengers "Earth's Mightiest Heroes".
After stealing the Tesseract during the events of “Avengers: Endgame,” an alternate version of Loki is brought to the mysterious Time Variance Authority, a bureaucratic organization that exists outside of time and space and monitors the timeline. They give Loki a choice: face being erased from existence due to being a “time variant” or help fix the timeline and stop a greater threat.