Loki

Loki is the stepbrother of Thor (the God of Thunder) and is known as the God of Mischief. His thirst for power ultimately leads to him wreaking havoc across realms. However, while during Thor: Ragnorak he became an Anti-Hero, but met his end at the beginning of Avengers: Infinity Wars

Origin
Loki Laufeyson was originally the biological son of the ruler of the Frost Giants, Laufey. This makes him the rightful heir to their land, Jotunheim. Because Loki was too small and seen as a disgrace to the Frost Giants, Loki was abandoned and left to die shortly after his birth. Luckily for Loki, he was found by Odin, who was King of Asgard. Odin took him to Asgard and raised him as his own son. He and his stepbrother, Thor, are the princes of Asgard.

Superhuman Strength
Being part of Frost Giant inheritance, Loki has incredible strength that while it doesn't match Hulk levels of power, he was able to lift Tony Stark off the ground with ease. This was proven in the first Avengers movie.

Superhuman Speed
What Loki lacks in strength he makes up for in speed. He was capable of catching Hawkeye's explosive arrow mere inches in front of him before the arrow exploded in front of him, which was demonstrated in the first Avengers movie.

Illusions
Loki can make illusions of himself. These "clones" can act and look like Loki but pass through physical objects with a green outline. This ability was proven in both the first Thor movie and in Avengers.

Biography/History
At the beginning of his life, Loki was left to die by his biological father, Laufey, ruler of the Frost Giants, because he was deemed unusually small. Odin, King of Asgard, took him home to raise him as his own son and an Asgardian prince after a war between Asgard and the Frost Giants. Loki’s physical appearance changed dramatically when he was taken to Asgard and he would have been unrecognizable to a Frost Giant. The Queen of Asgard, Frigga, taught Loki everything she knew in the arts of sorcery.

Growing up, Loki focused on the art of sorcery to become the most powerful sorcerer in all Asgard. His brother, Thor, God of Thunder, chose instead to focus on physical prowess. Loki felt that he was constantly living in his brother’s shadows and believed himself to be the rightful heir of Asgard. All this time, Loki was unaware that he was a son of the Frost Giants. Driven by jealousy and his desire for power, Loki tried to sabotage his brother’s coronation ceremony by secretly opening the gates between Asgard and the Frost Giants so they could come to Asgard and retrieve something from Odin’s vault.

When this happened, Thor was angry and wanted to retaliate. Loki pushed him into doing this, directly disobeying what the King of Asgard had commanded him. Thor took his friends and Loki with him to attack the Frost Giants, and during this, Loki discovered that he was not at all affected by the touch of the Frost Giants, when he should have experienced great pain. Loki was enraged and demanded to know the truth from Odin. When he learned of his true heritage, Loki was unable to see the acts of Odin and Frigga as love; rather, he thought that his Asgardian family viewed him as a monster and a political pawn. Thor eventually got banished by his father, and Loki put Odin into a deep sleep. Loki was offered the position as acting King by his mother.

During this time, Loki tried to eliminate Thor, who was on Earth, by controlling The Destroyer. Thor sacrificed himself, though, to save the people of Earth. This led Loki to ease up on his brother and brought him back to Asgard. The Frost Giants, led by Laufey, infiltrated Asgard as well because Loki had arranged the attack, but Loki betrayed Laufey and killed him to prove his worth as the rightful King of Asgard. As Thor arrived, though, he destroyed the Rainbow Bridge, which destroyed Asgard’s connection to Earth and any other realm. This caused both Loki and Thor to start falling into the abyss, but Odin, who had newly awoken from his deep sleep, saved them both. Odin was not able to see Loki’s actions and intentions as good for Asgard, and because of this, Loki let go and fell into the abyss.

Falling through a wormhole, Loki met the Other and Thanos. In exchange for dominion of Earth, Loki promised Thanos the tesseract. Loki was also gifted a scepter that would allow him to control the minds of others. However, this scepter was also controlling him, fueling his hatred for his brother and the people of Earth. Through manipulation of  various members of the Avengers, Loki was able to retrieve the tesseract from Earth and use it to open a portal to allow the entire Chitauri army to attack Earth from atop Stark Tower. The Avengers were able to defeat Loki and close the portal. Thor returned to Asgard with Loki in chains and the tesseract in possession.

In a turn of events, Loki escaped his imprisonment through the work of some Dark Elves and was led to his mother. This caused him to be overcome with grief, and he agreed to partner with Thor to defeat the Dark Elves. Thor knew his brother would betray him and tried to prepare for this, but he did not anticipate Loki sacrificing himself to bring an end to the Dark Elves. Loki died, and the Elves escaped to Earth.

Loki faked his death. He returned to Asgard and posed as Odin for some time. Loki had sent the real Odin to an elderly care center in Midgard. Thor discovered this, though, and the two went to find Odin, only to find that the center he was sent to was destroyed. Doctor Strange offered to help Thor and Loki find their father, and when they arrived, Odin told them both he loved them as he was about to die. Odin also told them that upon his death, his eldest, the Goddess of Death, Hela, would be released from her banishment. This was a secret that Odin had never shared with Loki or Thor.

When Hela arrived, she destroyed Thor’s Hammer and sent both him and Loki to Sakaar, banishing them from the Bifrost. On Sakaar, Loki gained the favor of the Grandmaster and worked several other escaped Gladiators to join the Revengers, whose mission became to confront and destroy Hela on Asgard. While Thor and the Revengers distracted Hela, Loki escaped to Odin’s vault to resurrect the fire demon. He also wanted to steal back the tesseract, which contained the Space Stone.

While Loki and his brother made plans to restore Asgard on Earth, Thanos appeared and demanded Loki give him the Space Stone, threatening Thor’s life in the process. Loki gave up the tesseract so that his brother could live and offered to become a guide to Thanos. He pledged his loyalty to him before attacking him, which was his true intention. Unfortunately, Thanos predicted this move and snapped Loki’s neck, killing him.

Research

 * https://www.reddit.com/r/AskScienceFiction/comments/9dn4wk/mcu_did_laufey_know_he_was_lokis_father/
 * https://marvelcinematicuniverse.fandom.com/wiki/Loki#:~:text=Loki%20Laufeyson%20was%20the%20biological,Asgardian%20prince%2C%20along%20with%20Thor.
 * https://www.marvel.com/characters/loki/on-screen
 * https://marvelcinematicuniverse.fandom.com/wiki/Loki

Images

 * https://www.google.com/url?sa=i&url=https%3A%2F%2Fmarvel.fandom.com%2Fwiki%2FLoki_Laufeyson_(Earth-12131)&psig=AOvVaw2B8UnBIOC9q5lJ838oCZ_k&ust=1597949490078000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCKjnxYP4p-sCFQAAAAAdAAAAABAY
 * https://i.insider.com/5cd5d3c793a152319a4f5fb3
 * https://superpoweredfancastdotcom.files.wordpress.com/2017/04/lokiperformanceissues1-avengers.png?w=2720
 * https://i.pinimg.com/originals/31/51/8a/31518ab4f03b12f85ee1ef71eaf99a9b.gif
 * https://observer.com/wp-content/uploads/sites/2/2020/02/Thor-Ragnarok_KI_V19.jpg?quality=80