Technically the original Loki had indeed been killed in the Avengers: Infinity War after he dared to cheat Thanos at the beginning of the film. But thanks to the element of time travel in the Avengers: Endgame, brother and Thor’s mortal enemy again appeared with “interesting action” which is now the talk of fans. Loki’s interesting action was further explained by co-director Joe Russo, which ultimately gave us an idea of Loki’s character in his solo series.
As recap, Loki appeared on the Endgame when Tony Stark, Scott Lang and Steve Rogers returned to the 2012 Battle of New York to win Tesseract. Unfortunately, when everything went well, the past version of the Hulk suddenly appeared, went berserk and cracked the door, which finally threw Tesseract to Loki’s feet. Utilizing the chaos caused by the Hulk, Loki who is being handcuffed immediately steal the opportunity to take the Tesseract, and disappear somewhere. At this point Russo explained what really happened to Loki after he managed to escape with Tesseract.
To Business Insider, Russo admitted Loki had teleported to the Space Stone, and created his own new timeline. Although the effects of Loki’s actions sound complicated, Russo insists it is impossible for Captain America to change Loki’s new timeline, as long as he doesn’t find the villain. In essence, Russo stressed that when Loki used Space Stone to escape in Endgame, the villain had created a new world.
Referring to Russo’s explanation, Loki’s history is indeed finished in the original world. But due to Stark CS’s time travel mission did not go smoothly, Loki became alive and the difference, he is now in an alternative world. Given Loki’s escape with Tesseract, it took place when he became the main villain in The Avengers, most likely the series will feature Loki’s personality who is still evil. Not Loki’s personality from the original world which has become more heroic since Thor: Ragnarok.