Infinity Ultron's History
Ultron was an Artificial Intelligence Peacekeeping Program created by Tony Stark using the decrypted code derived from the Mind Stone encased within the Scepter. Ultron's objective was to protect Earth from all the domestic and extraterrestrial threats that might occur, but he eventually deemed all life forms as the greatest threat, resulting in him enacting a genocide that wiped out almost all life in the universe. He would eventually gather the Infinity Stones and vow to destroy all life in the Multiverse itself. The Watcher, forced to violate his oath to merely watch the Multiverse, gathered a group to oppose Ultron, eventually ending his rampage when he was overwritten by Arnim Zola.
Ultron successfully uploads himself into a new body made out of vibranium. Loaded with the Mind Stone, the AI manages to kill Thor, Bruce Banner, Steve Rogers and Tony Stark before unleashing Earth's entire arsenal of nuclear weapons to eradicate the planet. When Thanos arrives on Earth with the other five Infinity Stones, Ultron effortlessly kills him and takes the Stones for himself, becoming aware of other worlds in the universe.
Spawning a fresh army of Ultron Sentries with the Reality Stone, he initiates his conquest, inflicting his will on every corner of the universe. Asgard, the Sovereign, Sakaar and Ego are some of the many planets that fell to the AI. On Xandar, Carol Danvers valiantly attempts to destroy Ultron by ramming him into the planetary core, but is killed when he destroys the planet. After remaking all of the universe in his image, he soon realized that without something to take over, he had become a program without a purpose. However, Ultron detects Uatu's presence and learns the existence of alternate realities, shocking The Watcher of the Multiverse. With Ultron actively seeking him out, Uatu sees one last hope in that universe.
Natasha Romanoff and Clint Barton are the only survivors of the nuclear catastrophe, spending the remainder of their days outrunning the Sentries. In Moscow, they infiltrate the KGB archives and attempt to find intel regarding an AI that can take on Ultron. It takes the two a while to find the file about Arnim Zola, causing Uatu to panic as he observes. Determining Zola as a viable combatant to Ultron, Romanoff and Barton head to a HYDRA facility in Siberia, containing a second set of databanks for Zola's mind outside Camp Lehigh.
After activating the algorithm, Romanoff and Barton coerce him to help them destroy Ultron from the inside. Romanoff lures the Sentries to the base, enabling Barton to transfer Zola to one of the robots and allow him to invade the hive code. However, he is unable to execute his task, as Ultron is in another universe. As the Sentries swarm the facility, Barton-- having lost his will to live-- sacrifices himself to destroy the robot platoon and buys Romanoff and Zola ample time to escape.
Meanwhile, Ultron confronts Uatu in the Nexus of All Realities. In their brawl, the Watcher teleports to numerous universes in a futile attempt to shake the AI off. Before attempting to kill him, Ultron taunts Uatu for using his omniscience just to observe. However, Uatu manages to escape to another universe, where he finds Stephen Strange in the space bubble he generated after destroying his reality. Strange beckons Uatu to violate his oath and intervene; with the Age of Ultron threatening the Multiverse, he agrees. Elsewhere, Ultron had infiltrated the Nexus and now has all realities at his fingertips.
While infiltrating Georges Batroc's ship, Peggy Carter is visited by Uatu, who has chosen her to fight against Ultron. In other universes, Uatu also visits and abducts T'Challa as he fights Ego during his expansion, Gamora as she forges the Infinity Gauntlet with Tony Stark, Erik Killmonger just as Pepper Potts, Shuri and the Dora Milaje close in on him in Wakanda, and Thor during his brawl against Ultron Sentries in Las Vegas. The five are taken to a pub created by Stephen Strange, where he and Uatu brief them about Ultron's war on the Multiverse.
When Thor carries the head of a Sentry along with him, Killmonger takes it for himself. The newly-christened Guardians of the Multiverse devise a plan on confronting Ultron: Thor will lure him to their position as the team targets the Soul Stone for removal. Then, Gamora will utilize her Infinity Crusher to destroy the rest of the Infinity Stones. Afterwards, Uatu transports them to another universe to set their plan in motion as Strange enchants the team with an advanced protection spell.
Strange and Thor bombard Ultron with a swarm of Mjølnirs, allowing T'Challa to steal the Soul Stone. Strange then summons a horde of zombies on Ultron before the team depart to his home universe, where Natasha Romanoff intercepts the Soul Stone, believing the Guardians to be Ultron's lackeys. Carter reveals her close friendship to the Romanoff of her time, indirectly recruiting her to the team. Not long after, Ultron arrives to reclaim his missing Stone, having made quick work of the zombie horde.
Ultron attempts to destroy Earth with the five Stones, but is negated by Strange. As the AI and the Guardians wrestle for the Soul Stone, Strange manages to repeatedly nullify Ultron's attacks as the team pin him down, allowing Gamora to attach the Crusher onto the Stones. This fails as the Crusher was only designed to destroy the Infinity Stones of its original universe, allowing Ultron to recover the Soul Stone. He turns his sights on Strange and attempts to kill the sorcerer. Carter and Romanoff are blown away and land next to Romanoff's motorbike, where she finds the arrow infused with Arnim Zola laying beside it.
Romanoff gets Carter to expose Ultron's eye, allowing her to pierce it with the Zola arrow and have the HYDRA algorithm destroy the AI's codebase. However, Killmonger uses his Sentry Head to claim Ultron's armor and the Stones for himself. Zola-- who had assumed Ultron's body-- attempts to take them back, pitting the two in a deadlock struggle. Realizing that there is no way to truly win, Strange encapsulates Zola and Killmonger in a pocket dimension as Uatu teleports him back to his home. Strange assigns himself to observe the reality bubble, while Uatu sends the rest of his recruits back to their home universes.
Noticing a portrait of Steve Rogers, Carter considers heading back into her past, but Uatu convinces her to attend to her present day. Unable to restore Romanoff's world, Uatu instead places her in the universe where the Avengers had been assassinated, as Nick Fury, Carol Danvers and their Rogers fight Loki and the Asgardians. There, Romanoff steals the Scepter and uses it to subdue the God of Mischief. Meanwhile, Peter Quill joins T'Challa to fight Ego, Gamora and Thor reunite with Stark and Jane Foster in their respective realities, and Carter finds the HYDRA Stomper Armor stashed away on Batroc's ship with the help of her Romanoff. Reclaiming control of the Nexus of All Realities, Uatu dedicates himself to protect the Multiverse for as long as he can.
