Avengers 4 could finally resolve a lingering issue that has haunted Earth's Mightiest Heroes for years: the dreams Scarlet Witch revealed during Avengers: Age of Ultron. The scenes were a major foreshadowing of what to expect at the hands of Thanos, but so far things have seemingly played out quite differently.

In Joss Whedon's 2015 sequel, Wanda Maximoff (Elizabeth Olsen) used her powers derived from the Mind Stone to peer into the psyches of Tony Stark (Robert Downey, Jr.), Steve Rogers (Chris Evans), Thor (Chris Hemsworth), and Natasha Romanoff (Scarlett Johansson), creating vivid hallucinations that incapacitated the Avengers.  The film presents the dreams as Wanda preying on the Avengers' fears (especially Tony), but it's not that simple. The Avengers' dreams aren't just a plot device for Wanda to momentarily defeat the heroes, they seem to also to be prophecies towards future events in the MCU. Since Avengers 2's development, the changes behind the scenes at Marvel Studios, like the Marvel Creative Committee being dissolved when Kevin Feige's film studio moved directly under the Disney umbrella, ended up altering the direction of the MCU's overall story. Yet looking back at Age of Ultron, the story threads from these dreams induced by Scarlet Witch weren't abandoned, just refitted to suit the MCU's evolving direction.

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Age of Ultron isn't the most popular Avengers movie with fans and it was criticized for spending too much time setting up future MCU events. In hindsight, a lot of what was set up has been paid off. For instance, Whedon's decision to romantically pair off Bruce Banner (Mark Ruffalo) and Natasha Romanoff directly led to Hulk's disappearance from Earth to become the Grandmaster's (Jeff Goldblum) champion on Sakaar. Had Thor not reunited with Hulk on Sakaar and formed the Revengers, he might not have been able to save the Asgardian people from Hela (Cate Blanchett) in Thor: Ragnarok. Age of Ultron also introduced Vision (Paul Bettany), who became a pivotal player, not just as Scarlet Witch's love interest, but as the guardian of the Mind Stone, which the Avengers rallied to protect from Thanos' invasion in Wakanda.

But the dreams Wanda unleashed and forced the Avengers to confront haven't been forgotten. Those are key story points that still haunt the MCU and could provide clues to will become of the original six heroes in Avengers 4:

Thor's Dream of Ragnarok And Infinity Stones

Thor was sure that because he is "mighty" that Scarlet Witch's tricks wouldn't affect him, but the disturbing omens he saw seem to have come true by Avengers: Infinity War. The Odinson hallucinated that he was in a banquet hall of Asgard during a celebration (which contains a statue that was later seen on the Infinity War set), until a blind Heimdall (Idris Elba) confronted him and promised that Thor was "leading us to Hell." Gripping Thor's head, Heimdall announced, "You are a destroyer, Odinson!" as lightning cascaded around Thor. The lightning teased the new power levels Thor would gain in Ragnarok, but there's still more that can be read into what Thor experienced in this dream.

Heimdall accused Thor of being the cause of Asgard's destruction, which is now the guilt the God of Thunder carries since he did fail to save his world and most of his people. Indeed, no other Avenger would have to face the sheer amount of personal tragedy that Thor has endured recently. Obviously, the plans for Ragnarok (and Thor himself) significantly changed since this scene was shot, but it still works as a hint of what was to come - the destruction of Asgard. But does it also mean Thor can ultimately save Asgard? Thor's vision could be revisited in Avengers 4 as the time travel elements of the film may force the Odinson to confront this Age of Ultron dream and its ramifications again, which could spin it into a new perspective. Perhaps his dream means Thor must return to Hell, and somehow what Heimdall said actually holds the key to how Thor can undo all of the deaths and save his people.

Related: After Avengers 4, The Infinity Stones Need To Go Away

In Age of Ultron, Thor was also the first Avenger to be granted insight into the Infinity Stones, which he briefly saw during Scarlet Witch's induced vision. This led Thor to visit the Water of Sights, where he learned about the ancient power sources. Thor later left Earth to search for the Stones, without success, until Thanos literally came to Asgard's door and massacred half of Thor's people to acquire the Space Stone by killing Loki at the beginning of Infinity War. For the God of Thunder, revenge against Thanos in Avengers 4 could not be more personal.

Tony Stark's Dream of Dead Avengers

Tony Stark's was the first mind Scarlet Witch toyed with in Age of Ultron and the billionaire futurist was an easy target since no Avenger harbored more fear about the future. Tony nearly died when he carried a nuclear missile through a dimensional portal in The Avengers. The sight of the Chitauri invasion fleet in outer space haunted him ever since. Wanda showed Tony a vision of his greatest fear, that Earth had fallen to the alien invaders and the Avengers were dead because they simply weren't strong enough to prevent 'the inevitable'. Steve Rogers' last words, "You could have saved us!", traumatized Stark. Tony then became obsessed with building Ultron as "a suit of armor around the world." Tony's dream looks more like what was seen of Thanos in the original Avengers than how it all played out on Titan in Infinity War, but it could still be interpreted as a harbinger of what would happen on Titan.

In Infinity War, when Doctor Strange (Benedict Cumberbatch) and Wong (Benedict Wong) told Tony about Thanos and the Infinity Stones, Stark said "This is it!" because he had been dreading this moment for years. Tony then devoted himself to doing anything it took, including sacrificing himself, to stop Thanos. Of course, Thanos also knew about Stark, and despite Iron Man's best efforts to lead the Avengers and Guardians of the Galaxy, he still failed to take the Infinity Gauntlet from the Mad Titan (although Star-Lord's worst behavior bears a lot of the blame for that).

Ultimately, Thanos' finger snap seems to be the flashpoint where Tony's worst nightmare came true as he watched evil win and his friends die. However, what ended up happening isn't quite as absolute as Tony feared. Billions may be dead, but Tony's dream was wrong because the original six Avengers didn't die. This could actually end up infusing Iron Man with the hope he desperately needs to avenge the universe. The question now is whether Stark can somehow set it all to right in Avengers 4. Defeating Thanos should  put Tony's greatest fear to rest, but what will such an epic victory end up costing the billionaire genius?

Page 2: The Avengers' Remaining Dreams Yet To Be Fulfilled

Captain America's Dream Of Returning To The 1940s

Despite Steve Rogers' best efforts to assimilate to life in the 21st century, he tragically remains a man out of time. When Scarlet Witch peered into his mind, she didn't see Rogers' greatest fear but his secret desire - the thing he was robbed off - getting to continue his life after World War II with his one true love, Peggy Carter (Hayley Atwell). Thanks to Scarlet Witch, Rogers hallucinated a big band victory party in 1945. Peggy was there to greet him, promising "The war's over, Steve. We can go home. Imagine it." This showed that even though Rogers has built a life for himself with loyal friends and that the world needs him as the leader of the Avengers, he yearns to go back to the time and place where he really belongs. After all, he buried Peggy in Captain America: Civil War, severing his last living link to his past.

A huge question regarding Avengers 4 is whether or not Steve Rogers' dream will actually get to come true. There is evidence that time travel will be a key component of the film, likely thanks to Ant-Man's access to the Quantum Realm. But what will ultimately become of Captain America if the Avengers defeat Thanos and restore the billions of lives in the universe the Titan wiped out? Is returning to his 21st-century life to lead the Avengers (possibly still as a fugitive thanks to the Sokovia Accords) a just reward for all of Steve Rogers' sacrifices? Or will he actually gain his heart's desire and get to return to his own time to live out his days with Peggy if they put Thanos down? But if that happens, what would Steve Rogers living in the past mean for the timeline and the future of the MCU?

Related: What Ant-Man And Wasp's End-Credits Scene Reveals About Avengers 4

Black Widow's Dream Of Her Past

The other Avenger haunted by her past is Natasha Romanoff. Wanda induced a vision where the Black Widow remembered her days as a girl in the Red Room, the KGB's facility where she and other children were trained to become assassins. Specifically, Natasha recalled being told that she can't break because she is "made of marble" and worst of all, her 'graduation ceremony' where she was sterilized so she can never bear children. Black Widow is the most professional and efficient member of the Avengers, but her cool facade hides her many dark secrets and regrets, although she did share this part of her past with Bruce Banner at Hawkeye's family's farmhouse.

Natasha's past and resolving her lifelong trauma is something that will most likely be fully depicted and addressed in the upcoming Black Widow solo film. With Cate Shortland (Berlin Syndrome) signing on as director, the prequel depicting how Natasha Romanoff became the Black Widow - which could also detail her first encounter with the Winter Soldier - should finally hit theaters as part of the next phase of MCU films after Avengers 4.

As for whether or not Natasha survives next year's epic blowoff with Thanos, given that Scarlett Johansson is one of the actors expected to leave the MCU after Avengers 4, it's not yet clear whether Black Widow has a future in Phase 4 and beyond. However, Johansson is certainly returning to star in her long-awaited solo film, which should illuminate Natasha's mysterious past and, at last, give fans the full picture on just who the Black Widow is.

Next: Avengers 4 Shouldn't Kill The Original Avengers