Here are the plot lines Marvel seemingly just abandoned as the MCU grew over the years. Known for its interconnected storytelling, Kevin Feige and his team have successfully played the long game when it comes to building the MCU. Seemingly unimportant details from previous films ultimately mean something in its contemporaries, effectively establishing a cohesive universe. However, not all planted plot seeds got pay offs, others were simply cast aside, never to be visited again.

The MCU prides itself for preserving a single continuity since it kicked off in 2008 with Robert Downey Jr. and Jon Favreau's Iron Man. It's a big factor in successfully executing a culminating project such as Avengers: Endgame, which was chock full of references from previous films. Whether it's direct crossovers or more subtle Easter eggs, this interconnectivity is a key part of the MCU's appeal and success.

Related: Marvel May Not Have An MCU Phase 4 At All

While Marvel Studios crafted a satisfying ending to the Infinity Saga, it left some unanswered questions moving to Phase 4. There are also smaller narratives from MCU's 11-year-history that were supposedly leading somewhere but ultimately didn't - either because they're forgotten or Marvel's plans changed.

Iron Man's Demon in a Bottle

Tony Stark Drinking and Iron Man Armor

The first shot of Tony Stark (Robert Downey Jr.) in Iron Man shows him holding a bottle of bourbon during his visit to present the Jericho in Afghanistan. Fans of the comics immediately assumed that this was the MCU's attempt in bringing the character's Demon in a Bottle print storyline into the big screen. Iron Man 2 once again teased the idea of Stark's alcoholism when the genius billionaire drunkenly threw a birthday bash while suffering from palladium poisoning, forcing Rhodey (Don Cheadle) to get involved. After that, this aspect of the character was never brought up in the franchise again. While The Avengers and Avengers: Age of Ultron did show him having a glass, both instances called for it. He stalled Loki while charging his suit in the 2012 film and he mingled during the Avengers tower party after they secured the Scepter/Mind Stone from HYDRA, but otherwise the storyline wasn't revisited.

The Leader

Samuel Sterns aka The Leader in The Incredible Hulk

Marvel Studios' may have recasted Bruce Banner from The Incredible Hulk's Edward Norton to Mark Ruffalo, but the Louis Terrier film is still part of the MCU continuity. This is evidenced by the re-emergence of Thunderbolt Ross (William Hurt) later on after debuting in the said standalone among other things. One particular tease from the 2008 film hinted at Dr. Samuel Stern (Tim Blake Nelson) eventually becoming the Leader. Stern was exposed to the blood of the Hulk after injecting Emily Blonsky (Tim Roth) with it; and the he last fans saw him, his head was already starting to expand - mimicking the Leader's appearance in the comics. 11 years after, fans still don't know what happened to Stern as he continues to be absent in the MCU.

Other Countries Imitating the Iron Man Technology

Tony Stark at the senate hearing in Iron Man 2

After announcing to the world he is Iron Man, the government quickly became enamored with the technology Tony Stark created. In Iron Man 2, he fought to keep his creation to himself, refusing pressure to sell it off. In the iconic senate hearing scene, it's revealed that other arms dealers and even countries are trying to replicate the impressive metal suit for their own use. Once presented with footage of test runs all over the globe provided by government intelligence, Stark said that the replicas are mostly 5 to 10 years away from coming close to a functioning suit. He used this to prove a point that there's no immediate threat that demands the government to acquire his creation. It's been more than the time frame Stark gave in the MCU, and yet, there's no word on any other country or weapons manufacturer successfully creating their own Iron Man suit.

Related: Iron Man: The One Thing The MCU Never Properly Resolved

Thor's Nine Realms

Thor MCU nine realms missing Alfheim

The Nine Realms are deemed important in Thor's MCU story. Comprised of Asgard, Midgard, Jotunheim, Svartalfheim, Vanaheim, Nidavellir, Niflheim, Muspelheim, and Alfheim, most of of these planets factored in the MCU one way or another, although the last one has yet to be explored. In the first Thor film, Marvel Studios attempted to tackle the difference between magic and science, with Thor (Chris Hemsworth) telling Jane (Natalie Portman) that from where he is from, they're essentially the same thing. In the same conversation, he explained that the Nine Realms of the cosmos are separated worlds connected by the world's tree called Yggdrasil. After that, this idea was never fully explored again. While succeeding films did feature the other Nine Realms including Nidavellir in Avengers: Infinity War, their supposed connectivity with each other didn't necessarily factor in any of the more recent narratives even with Asgard getting destroyed in Thor: Ragnaork.

Lady Sif’s Absence

Thor Lady Sif

As Thor's good friend, Lady Sif (Jamie Alexander) was a staple of the God of Thunder's early adventures in the MCU. Aside from appearing on the first two Thor films, she also guest starred in Agents of S.H.I.E.L.Dappearing twice - the latter of which marked her last sighting in the universe. By the time the events of Thor: Ragnarok rolled around, the formidable warrior was nowhere to be found. Directors Joe and Anthony Russo did confirm that she was among the unfortunate beings who were snapped out of existence by Thanos' decimation in Avengers: Infinity War, which means that she should've been resurrected by Smart Hulk's snap in Avengers: Endgame. Off-screen, Sif's absence in Ragnarok was due to scheduling conflict, although it's curious why Marvel Studios didn't ask her to partake in Endgame's climactic battle. Even with Thor: Love and Thunder confirmed for Phase 4, there's no indication of Sif's re-emergence in the MCU, leaving fans wondering what really happened to her.

Bruce Banner's Tragic Love Affairs

Avengers Endgame Hulk Snap Betty Ross

Bruce Banner (Mark Ruffalo) doesn't have the best of luck when it comes to romances. While his fellow Avengers like Iron Man and Captain America (Chris Evans) had great love stories with the same woman throughout their MCU stints, it doesn't seem like Banner is made for relationships. He has not one, but two affairs that didn't go anywhere since the character debuted in The Incredible Hulk. Despite recasting, the origin movie is deemed canon as previously mentioned, hence why Banner's short-lived relationship with Betty Ross (Liv Tyler), which doesn't have a definitive ending, is essentially part of his personal narrative. Betty has yet to re-emerge since The Incredible Hulk, even with her father Ross returning to the MCU, factoring in Captain America: Civil WarInfinity War and AvengersEndgame.

Avengers: Age of Ultron also attempted to introduce a new romance for Banner in Natasha Romanoff (Scarlett Johansson). In the Joss Whedon-directed flick, the pair bonded over their common fears stemmed from their respective past traumas. At one point, they even discussed running away to live a normal life together. That obviously didn't happen with Banner going missing for years until he reunited with her in Infinity War. However, as they fought Thanos and subsequently dealt with the aftermath of his snap, Nat and Banner never got the chance to talk about what really went down between them as she met her end in Endgame.

Related: Marvel's She-Hulk Show Can Finally Give Incredible Hulk An MCU Sequel

The Sokovia Accords

Introduced in Captain America: Civil War, The Sokovia Accords is an international treaty that gives the U.N. power to regulate superheroes' activities. That meant that the governing body will decide which issues the Avengers will be involved with, and which ones they will sit out dividing the heroes as some were for it, while others against it, resulting in the Earth's Mightiest Heroes breaking up. The agreement was in place for two years wherein those who opposed it such as Captain America, Falcon (Anthony Mackie), and Black Widow created a splinter group known as the Secret Avengers. They continued their operation underground until they emerged in Avengers: Infinity War in preparation for Thanos' arrival.

By Avengers: Endgame, the remaining heroes, including those who refused to sign The Sokovia Accords, can freely roam around - Captain America was even a member of a therapy group. Even as MCU characters gathered at Stark's funeral, including General Ross, the treaty wasn't brought up. It also didn't factor into Peter Parker's (Tom Holland) adventures with and against Mysterio (Jake Gyllenhaal) around Europe in Spider-Man: Far From Home. As the MCU moves forward with Phase 4, The Sokovia Accords will be left in the past without having proper dissolution.

The Existence of Damage Control

Marvel Damage Control

While they didn't have a bigger impact in the MCU until Spider-Man: Homecoming, the Damage Control team was in the franchise as early as Iron Man. Created and initially operated by S.H.I.E.L.D., the organization acquires and stores unique artifacts from superhero battlegrounds, masking it simply as a clean-up drive. Over the years, it was mentioned sporadically as they took care of the aftermath of Stark's fight with Iron Monger (Jeff Bridges), as well as the Triskelion mess in Captain America: The Winter Soldier. It made its biggest impact in Spider-Man: Homecoming's flashback scene, where their involvement in the Battle of New York cleanup resulted in Adrian Toomes' (Michael Keaton) Bestman Salvage losing their contracts. Damage Control hasn't factored in any other MCU narrative since (with plans for a TV show scrapped), with no indication that they will re-appear anytime soon.

More: Every Upcoming Marvel Movie (2020 - 2022)

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