Hulk (MCU)'s History
Robert Bruce Banner, M.D., Ph.D., is a renowned scientist and a founding member of the Avengers. As someone who was highly respected for his work regarding biochemistry,nuclear physics
, and gamma radiation, he was commissioned by Thaddeus Ross to recreate the Super Soldier Serum which created Captain America, although Ross elected not to inform Banner what he was creating. However, when an exposure to high levels of gamma radiation instead of vita radiation went awry, the mild-mannered scientist had found that when angered, provoked or excited, he would transform into the huge, rage-fueled, nearly mindless creature known as Hulk. Fearful of the damage that Hulk could inflict as well as fleeing from the
United States government
, Banner attempted to commit suicide; when the attempt failed, he chose to live a discreet life in South America while also communicating with Samuel Sterns to cure himself. However, when General Ross had sent a team led by Emil Blonsky to apprehend Banner, he was then forced to return to New York City where he recruited the help of Betty Ross and Sterns to cure him of his affliction. Banner was apprehended by the Armed Forces shortly after, but Blonsky, who had received a variant of the Super Soldier Serum, was administered Banner's gamma-irradiated blood, transforming him into the Abomination and forcing Ross to allow Banner to turn into Hulk and battle him before then allowing Hulk to escape.
Banner fled the United States and dedicated his time to aiding the sick and poor. When a mounting threat called for Banner's specialized scientific expertise, S.H.I.E.L.D. recruited him, knowing full well that the incredible strength of Banner's alter-ego, Hulk, would be an additional asset to the Avengers. Banner was tasked with tracking down the Tesseract, working alongside Tony Stark to achieve this. Despite almost causing a disaster when he was forcibly transformed into Hulk by Loki, Banner joined the Avengers during the Battle of New York and assisted them in defeating Loki and his Chitauri army. Once the Avengers split up in the wake of the battle, Banner had become good friends with Stark and relocated to the Avengers Tower, free to live his life without apprehension.
In the wake of the HYDRA Uprising, the Avengers regrouped once more to battle the ever-growing threat of HYDRA, successfully capturing Wolfgang von Strucker and retaking the Scepter. In order to make it so that Earth could always be safe without constantly needing the Avengers to protect it, Banner assisted Stark with creating Ultron, an artificial intelligence. Ultron, programmed to protect Earth at all costs, deemed humanity and the Avengers as its greatest threat and focused on annihilating them. Banner was then enlisted by Stark to help create Vision, and was later coaxed by Black Widow into transforming into Hulk and help defeat Ultron. Following Ultron's defeat, Hulk commandeered a Quinjet and left Earth, flying into space and coming across a wormhole that caused the Quinjet to crash on the planet Sakaar, where the stressful environment prevented him from regressing back into Banner, causing him to remain in Hulk form for two years.
On Sakaar, he became a gladiator for Grandmaster and was soon revered as a beloved champion, choosing to turn his back on Earth and enjoy the life of an admired warrior. However, when Thor arrived on the planet, Hulk fought against his old friend in the arena. In the wake of their fight, Thor informed Hulk that Asgard was under threat due to Hela's return. Hulk aided the Asgardians in their fight, defeating Fenris and allowing the Asgardians to board the Statesman vessel, and as Ragnarök was unleashed, joined them on their voyage to Earth.
On their way back to Earth, the Statesman was attacked by the Black Order, who killed half of the Asgardians. Hulk challenged their leader, Thanos, who soundly defeated him. He was then teleported to the New York Sanctum by Heimdall, where Banner warned Doctor Strange, Iron Man and later Captain America of Thanos' arrival. Finding himself no longer able to transform into Hulk, Banner operated a Hulkbuster armor to aid the Avengers in the Battle of Wakanda. Although Banner and his allies managed to kill off Thanos' forces, Thanos personally arrived in Wakanda to retrieve the Mind Stone. He effortlessly subdued Banner and the other heroes and completed the Infinity Gauntlet, wiping out half of the universe's population, with Banner being one of the survivors.
Some time after the Snap, Banner permanently merged himself and Hulk into one being, which combined Hulk's raw strength and physique with Banner's mind and intelligence and turned him into an adored celebrity. In 2023, he rejoined the Avengers to help them use Pym Particles and the Quantum Realm to travel through time. After traveling back to the Battle of New York in 2012, Banner successfully gained the Time Stone from the Ancient One and returned to the present. He and Rocket Raccoon helped Tony Stark design the Nano Gauntlet to contain the Stones the Avengers had collected. Banner elected to use the Stones to resurrect all the lives claimed by the Snap, injuring himself in the process. In the aftermath of the Battle of Earth, which resulted in Iron Man's death, Banner sent Captain America back in time.