THIS ESSAY WILL ALSO GIVE AWAY THE BEGINNING OF THE AVENGERS: INFINITY WAR. IF YOU HAVEN'T SEEN THE MOVIE YET AND YOU DON'T WANT ANYTHING IN IT TO BE RUINED, SEE IT BEFORE READING THIS.
IF NOT FOR YOUR OWN SAKE, THEN DO IT FOR LOKI'S.
Thor: The Dark World (2013)
I bring this up because it showed how aware Marvel was of Loki's popularity at the time, as well as how keen they were to play to it. I think that contributed a lot to his role in The Dark World.
The filmmakers knew we wanted to see him turn good and team up with Thor. They knew we debated if and how he would die in future films, and they knew how much we wanted to see him succeed for once. Because of this, there was a real sense that they toyed with our expectations for Loki in the second Thor film, and the end result was perfect for his character.
Loki hit rock bottom in The Dark World. Not only was he disgraced before all of Asgard, but Odin seemed to disown him and left him virtually powerless by imprisoning him. Then, when Loki thought things couldn't get worse, he caused the death of his adoptive mother Frigga. The dark elf Malekith invaded Asgard, and when a henchman named Kurse found Loki in the dungeon, Loki told him the way to the throne room. He did this for revenge on Odin, but it was Frigga that Kurse killed instead.
His chance came during a fight between him, Thor, and Kurse on the dark elves' home world. Loki killed Kurse, saving Thor and avenging Frigga, but he was wounded in the process. Thus we got the scene we were expecting where he died dramatically in Thor's arms after redeeming himself. The twist was that it wasn't real.
To my knowledge, it's never been confirmed if Kurse really stabbed Loki, since Loki's powers allowed him to cast illusions of such things. Either way, he wasn't fatally wounded, but he took advantage of Thor's emotional state and faked his own death. Thor was forced to leave him behind and pursue Malekith, one of Odin's guards found Loki, Loki killed the guard and assumed his appearance (possibly even disguising the guard's body as his own), and returned to Odin. After that, he used his powers to trap Odin on Earth, assumed his adoptive father's appearance, and took on a new life as the King of Asgard. At long last, the God of Mischief had succeeded.
What's interesting is that he never sought further revenge on Thor after his brother defeated Malekith and came home. Thor had broken Loki out of prison and committed treason by leaving Asgard, so no one would have questioned a steep punishment for the God of Thunder, but Loki allowed Thor to go free and live happily on Earth with his human friends. Maybe he had made some kind of peace with Thor during their time together, maybe he couldn't properly restrain Thor since he didn't have any of Odin's powers, or maybe he thought that letting Thor leave Asgard on good terms would minimize suspicion towards himself. Whatever the reason, fully pardoning his brother after everything they had put each other through showed growth on Loki's part.
Thor: Ragnarok (2017)
It would take four years for Loki to show up again in the MCU. He was supposed to make a cameo in 2015's The Avengers: Age of Ultron when Thor had a vision of Asgard's destruction, but like a lot of things in that film, he was cut for time. Between that and all the questions that The Dark World had left us with, there was still a good amount of excitement for Loki's comeback in Thor: Ragnarok.
In terms of the narrative, this character inconsistency can actually be justified. Loki spent his whole life seeking admiration and eventually power, and once he gained both at the end of The Dark World, he had no goals left to work towards. This caused him to lose a lot of his drive and his edge over the four years he spent disguised as Odin, and not having to worry about Thanos finding him anymore allowed him to become oblivious to the world around him. It made sense that after Thor caught on and exposed him as an imposter at the start of Ragnarok, Loki had to spin his wheels a bit before finding a new direction in life.
He hit rock bottom again after Thor made him take them to the real Odin on Earth. The brothers found their father moments before he died, and although Odin forgave Loki, his death was one betrayal too many for Thor to do the same. The final nail in the coffin came when Thor's half-sister Hela sensed Odin's passing and seized control of Asgard.
This marked the ultimate turning point for Loki. All his schemes of the past seven years had been for nothing, and having Thor completely give up on him this time made him finally realize what he had ruined between them. What was more, he had no guarantee that he would be safely hidden from Thanos on Sakaar. There was a chance he might die soon anyway, so why not die doing something genuinely admirable?
After making his own escape from Sakaar, Loki took his brother's words to heart and returned to Asgard to help Thor defeat Hela. This involved destroying their home like Thor had foreseen, and it was Loki who set that destruction in motion. Curiously enough, he had to do it in Odin's vault—the same room where he had first learned of his Frost Giant lineage. The ship that he had arrived on allowed Asgard's people to evacuate in time, and Loki further proved his loyalty by joining them on their voyage to Earth. It was during this voyage that he made his peace with Thor and watched his brother assume the role of Asgard's new king.
The Avengers: Infinity War (2018)
And that brings us to the grand finale. Infinity War is still less than two weeks old, and it's already broken the record as the fastest movie to ever gross $1 billion at the box office. It's well on its way to becoming the highest grossing film of all time, and I think that's largely because of how many upsetting character deaths occur throughout the plot. Fans want to figure out how the next Avengers film will resolve things, if it even can, and a good way to look for clues is by watching Infinity Wars again. And if that doesn't work, then at least they'll get the most out of what could be their favorite characters' final appearances on the big screen.
The film is shocking and bleak, and Loki's death in the opening scene sets that tone perfectly.
Even then he wouldn't hand over the Tesseract, since he knew what his enemy meant to do with the stone inside. It wasn't until Thanos started torturing Thor in front of him that Loki revealed the device, though he still didn't give up. He stalled for time so the Hulk could attack Thanos, and when the Hulk lost that fight, Loki attempted to finish the job himself.
Loki often defeated opponents by distracting them with illusions of himself and then striking from behind. However, he didn't do that this time; perhaps he decided he was through with hiding. Instead he faced Thanos himself, pretended to offer his services again, and tried to stab his former ally in the throat. Sadly, the God of Mischief really had become predictable, and after stopping the blow, Thanos lifted him into the air by his neck while Thor watched helplessly. Loki declared that the Mad Titan would never be a god, then Thanos killed him with one squeeze. The last we saw of Thor's little brother was his body lying on the floor while the God of Thunder grieved over him.
I've heard complaints that this sendoff for Loki was anticlimactic, but I disagree. The scene pretty much covered all the bases it needed to for his story arc: proving that he valued his brother's life more than his own ambition, having him team up with two of the Avengers to an extent, showing that he'd accepted his past by stating he was Odin's son but not an Asgardian, and letting him get in a few last tricks and interesting lines. I even kind of like that his death was so simple and blunt this time. He already had an epic sci-fi spectacle death in the first Thor film and a dramatic Shakespearean death in the second, so it was fitting that his third death had none of those theatrics. That sold the reality of it so much more.
Production photos of the fourth Avengers movie have surfaced since Infinity War's release. Because they appear to take place during the events of the first film and feature the characters wearing mysterious wrist devices, fans have speculated that the story will involve time travel to undo the final moments of Infinity War. It's possible that Loki could "return" that way, with Thor encountering a past version of his brother. There's also hope that he might come back from the dead as a result of the Avengers meddling with the past.
If this is the last time we'll ever see Loki, I'll close with this: When he first saw himself as a Frost Giant, he wondered if he was cursed. He was right in a way. His curse was that for all the cunning and strategic thinking he possessed, his emotions were always what ended up dictating his choices. In this regard, he was more like Thor than he wanted to believe, and since he never had the same opportunity as Thor to learn self-control, his emotions continued to sabotage him at every turn. When he saved the Tesseract from destruction on a whim, the penalties of this curse became cataclysmic.
Still, there was a way Loki could have kept the Tesseract out of Thanos's hands. All he had to do was keep it cloaked in invisibility, refuse to say it's location, and let Thanos kill Thor. That would have been the more sensible choice in the grand scheme of things, since Thanos wanted the Infinity Stones to "save" the universe by committing genocide. However, Loki's emotions pushed him to reveal the device in exchange for his brother's life.
Several other characters, mostly the heroes, had to choose between someone's life and an Infinity Stone throughout the film. Most of them gave up the stone to spare the person's life. The only willing exception was Thanos, who tortured one of his own children and killed another to claim a stone. Loki may never have quite been a hero, but in the end, he had more in common with the heroes than he did with the villain. The son of Odin who had once tried to kill his brother and save Asgard by also committing genocide had replaced his hate with compassion, and his emotions made the better choice as a result.
In the end, Loki understood the value of life, and that's no curse.