When fans walk out of Avengers: Infinity War, most are wrapped in a cloud of stunned silence thinking "What did I just watch?" Then the stages of grief sink in: denial, anger, bargaining, depression. For many, the final stage still hasn't been reached: acceptance. They're still looking for someone to blame for all this. The good news is there's a very good candidate. The bad news is, he's dead. And not "dissipated, probably going to be undone dead," but dead-dead. If fans go back through all 18 installments which lead them here, this Avengers: Infinity War Loki theory says there's only one person to blame: the Trickster God himself.
How does that work? Let's run down the evidence.
The first three films of the MCU are Iron Man, The Incredible Hulk, and Iron Man 2. Two dudes getting their invention and science on, all relatively Earth-centric in their focus. It's not until film four, Thor, which came along in 2011 where space and magic started to get involved. Also? Loki.
In Thor, Loki basically puts Earth on the map, first by getting Thor banished there, and then coming down to beat him up with robots in New Mexico, making Earth aware of them. But it's the end credits scene where things start to go terribly wrong. In it, Loki finds out about the Tesseract, the Space Stone, one of six Infinity Stones.
In Captain America: The First Avenger, the clock is rewound to show where the Tesseract came from, and why Nick Fury has it in the first place. Unfortunately, Fury doesn't see fit to tell Steve Rogers they have said stone, or the fact they've asked Selvig to run tests on it.
The very next movie opens up with Loki, consulting with one of Thanos' minions. He now has the Scepter, a gift from Thanos to help him defeat Earth and bring the Mind Stone. In return, Loki will be given back his rulership of Asgard and dominion over Earth to boot.
The biggest mistake? Loki believes him.
Next thing viewers know, there's big hole in the sky over New York, the Avengers team up to fight, and Tony Stark accidentally gets Thanos' attention. So does Earth, it's no longer some muddy backwater in a far-off quadrant in a boring little corner of the galaxy. Thanos knows he needs more power to go and defeat it.
Moreover, Loki makes a mistake. Not only does he not get the Tesseract for Thanos, but he loses the Scepter in the process, putting two Infinity Stones on Earth. Thor, at least, takes one with him.
In Iron Man 3, Fury is still trying to harness the power of the Infinity Stones, now with the Mind Stone but that's as far as the stones are mentioned. It's Thor: The Dark World where things go wrong again, and once more it's Loki to blame. Odin dies in the film, but rather than allowing someone who would pay attention and do the job of guarding the universe, Loki takes over wearing Odin's face and then spends the next four years ignoring the universe.
This includes not coming to Nidavellir's rescue when Eitri needs him, so he forges the Infinity Gauntlet. It also means he's not paying attention to all the stuff in Odin's vault so when said Infinity Gauntlet gets switched out for a fake so Thanos has the real one back, he doesn't notice either.
It also includes not paying any attention to Thor, who is down on Earth attempting to quell the chaos the Infinity Stones are making....like the experiments on the Mind Stone, which create Wanda Maximoff's powers, which she uses to show Tony Stark a horrifying future.
Starks vision causes the creation of Ultron, and a Sakovia Accords, which divides the Avengers just when they need to be coming together. (Also? It creates Vision, a living being with the Mind Stone inside.) Because Thanos is getting impatient.
All this builds up to the current day, and the events of Thor: Ragnarok when Loki's lack of attention not only causes Hela to return but Thor to learn most of what is in the Vault is fraudulent. The only real thing? The Tesseract, which he personally put there.
At least it could have been destroyed, thwarting Thanos' plan, but Loki, still remembering he owes this stone to Thanos, rescues it before they leave, leading Thanos right to the Asgard ship, and all which takes place in Infinity War.
So thanks Loki. Now Heimdall is dead, and so are you, and half the universe has been dissipated in an event religious fundamentalists all over Earth are going to claim is the rapture. When The Sill-Untitled Avengers 4 film comes out on May 3, 2019, I'm blaming you.