Thanos could be the real cause of Doctor Strange in the Multiverse of Madness. At San Diego Comic-Con 2019, Marvel Studios finally confirmed that Doctor Strange 2 is in the works and, while the Multiverse may have been fake in Spider-Man: Far From Home, the Sorcerer Supreme is about to face the real deal.
It's important to remember, though, that the first Doctor Strange film used the term "Multiverse" in a slightly different way. Rather than link the concept to alternate timelines, Doctor Strange referred to other planes of existence, like the Dark Dimension and the Quantum Realm. The Ancient One, leader of the Masters of the Mystic Arts, was sworn protector of this plane of reality. "Learning of an infinite multiverse includes learning of infinite dangers," she cautioned Stephen Strange. Unfortunately, the Ancient One was killed during the conflict with Kaecilius, and a concerned Wong reflected that news of her demise would spread throughout the Multiverse. He clearly feared that Earth had lost its greatest defender.
It seems that Wong's fears were justified, with Stephen Strange - the man destined to become the next Sorcerer Supreme - forced to confront a Multiverse of Madness in 2021. But how exactly has that problem come to be? Many have pointed towards Scarlet Witch, whose Disney+ series WandaVision will tie directly into Doctor Strange 2. However, the real cause could have been Thanos in Avengers: Endgame.
Thanos Destroyed The Infinity Stones At The Start Of Avengers: Endgame
For all Thanos considered himself to be a cosmic necessity, he was never overly concerned about the fabric of reality itself. Indeed, in Avengers: Infinity War Thanos used the Time Stone to reverse the destruction of the Mind Stone; that's a pretty dangerous feat, given that in Doctor Strange Wong and Mordo feared that Strange was breaking the entire time-space continuum when he simply manipulated time around an apple. "Temporal manipulations can create branches in time," Wong cautioned. "Unstable dimensional openings. Spacious paradoxes! Time loops!" Thanos knew how to use the Time Stone, so it's reasonable to assume he had a good idea of the risks. He just didn't care. This has even led to theories that Scarlet Witch did beat Thanos at the movie's climax.
He took that to the next step in Avengers: Endgame. When the Avengers arrived at the Garden, they were horrified to learn that the Mad Titan had used the Infinity Stones one final time - in an act of self-destruction, reducing them down to their constituent atoms. In Thanos' view, he no longer needed the Infinity Stones now he had achieved his insane goal and killed half the life in the universe. They would serve as a constant source of temptation for his enemies, who would know they could seek them out and undo what he had done. Thus it was necessary to destroy the Infinity Stones in order to preserve his triumph.
The Infinity Stones Define Time - And Bad Things Happen Without Them
There are subtle difference between the traditional comic book portrayal of the Infinity Stones and the MCU versions. In the comics, each Infinity Stone stands as a representative of an aspect of reality - from Mind to Power, Time to Soul. The MCU has traditionally been wary of going quite that far, with the Collector suggesting that they were forces from the universe before ours, somehow compressed into "concentrated ingots" by powerful, ancient beings - possibly Celestials.
Still, Avengers: Endgame stressed that they do serve some sort of important role in the nature of reality itself. "The Infinity Stones create what you experience as the flow of time," the Ancient One explained to Bruce Banner, implying that all of existence is bound somehow to the power of the Infinity Stones. That was why removing an Infinity Stone would create an alternate timeline; because an important aspect of reality had been taken away.
According to the Ancient One, removing a single Infinity Stone would create a doomed timeline. This is probably particularly true of the Time Stone, which the Masters of the Mystic Arts have used as a weapon in the defense of Earth and their dimension. The Ancient One admitted she used the Time Stone to peer into the future and identify potential threats; in Avengers: Infinity War, Doctor Strange used it to explore potential timelines and identify one where the heroes won; and when Strange went up against Dormammu, he demonstrated just how powerful a tool the Time Stone could be.
Now, though, all six Infinity Stones are gone - and the Masters of the Mystic Arts have lost their greatest weapon.
Did Thanos Start Doctor Strange 2's Plot?
All this raises the disturbing possibility that Doctor Strange In The Multiverse Of Madness flows directly out of the events of Avengers: Endgame. If the Infinity Stones are somehow tied to the nature of reality, then their destruction was an act of cosmic vandalism, and Thanos has done potentially irreparable damage to the universe itself. In the best-case scenario, the damage will escalate and universal constants including the laws of time and space will begin to unravel. There's comic book precedent for this idea; 2013's Age of Ultron event saw the Avengers unwittingly break time and reality fracture around them. Realities merged, portals opened between the dimensions, and living beings were transported between alternate timelines. Incredibly, Tony Stark considered that things could have been a whole lot worse. "I think we're lucky we still exist in a cohesive linear reality," he told the Avengers.
In the MCU, Doctor Strange revealed that the Multiverse is filled with dangerous threats, eager to consume the Earth. With the Infinity Stones destroyed, it's possible Earth's plane of existence will begin to open up to forces and beings from other dimensions, giving them the opportunity to prey upon a helpless planet. Worse still, without the Time Stone, Doctor Strange and the Masters of the Mystic Arts would have no way of seeing them coming. Furthermore, Doctor Strange will be unable to repeat his Endgame plan, where he peered into infinite futures and identified one in which the heroes won eventually. The Masters of the Mystic Arts will be reduced to reacting to crises, and they'll just have to take their best shot, hoping things work out.
At this stage, of course, this is just a theory; but it fits perfectly with the MCU's general pseudo-science, and it has the advantage of explaining why Marvel needed to wait until after Avengers: Endgame before releasing Doctor Strange 2. If this theory is correct, the Mad Titan is essentially the proximate cause of Doctor Strange 2, and the sequel will explore the cosmic repercussions of his actions.