In the finale of "What If...?" Season 2, titled "What If... Strange Supreme Intervened?", the narrative takes a dramatic turn as Strange Supreme and Captain Carter find themselves in a high-stakes battle across the multiverse. The episode begins with a brief recap of their histories, setting the stage for their return to the 1602 universe after Carter's successful prevention of an incursion. Strange reveals his true mission—to capture "universe-killers" and safeguard the multiverse—but admits that one has escaped, necessitating Carter's assistance in recapturing the threat before they can return home.
The duo arrives in a universe where Hydra emerged victorious in World War 2. Carter quickly discovers that Strange's escaped prisoner is none other than Kahhori, who was deceived by Strange with a fabricated tale of universe-killers. Kahhori exposes Strange's sinister plot: he has been capturing powerful beings from across the multiverse to harness their energy in a device known as the Forge, in a desperate attempt to resurrect his own universe, which he had destroyed in a failed bid to save Christine Palmer's life.
As Carter and Kahhori navigate the treacherous corridors of Strange's Sanctum, they encounter a rogues' gallery of captives, including Hela and Zombie Scarlet Witch. Carter frees these prisoners, using them as a diversion while they search for the elusive Forge. Their journey leads them to Black Panther Kilmonger, who has been imprisoned since his battle with Ultron in the first season of "What If...?". Kahhori's teleportation skills are instrumental in transferring the Infinity Armor from Kilmonger to Carter, empowering her with the power of the Infinity Stones to confront Strange.
Carter and Kahhori finally reach the Forge, only to be intercepted by Strange, who is determined to protect his creation at all costs. As the conflict escalates, Kahhori targets the Forge while Carter engages Strange in a fierce duel. Strange, succumbing to his demonic side, gains an edge over Carter, even resorting to dumping prisoners into the Forge to rekindle his universe. However, Carter and Kahhori, bolstered by the support of the prisoners, manage to shield them from harm using their combined powers and the Infinity Stones.
Strange's desperation leads him to employ illusions, recreating the scene of Steve Rogers being injected with the Super Soldier Serum in front of Carter, but Carter sees through his trick. Amidst the chaos, the prisoners realize that Carter and Kahhori are their best chance for survival and begin throwing their weapons to them to gain an advantage against Strange. Kahhori then sends the prisoners home, while Carter separates Strange from his demonic form, trying to reason with him.
Ultimately, The Watcher saves Kahhori and Carter, with the former being sent back to her universe, along with members of her tribe who were also imprisoned by Strange. It is then revealed that Strange's sacrifice was able to restore his universe and Christine Palmer, but at the cost of his own existence, as he was never born into it.
In this universe, Carter and Kahhori must protect the prisoners from Strange's harm, while Strange nearly engages them in a evenly matched duel. Strange even attempts to defeat Carter with an illusion of the day Steve Rogers was meant to be injected with the Super Soldier Serum, but she is able to see through it.
The prisoners, recognizing that Carter and Kahhori are their best chance at survival, begin throwing their weapons to the duo, giving them the upper hand against Strange. Kahhori manages to send the prisoners home while Carter separates Strange from his demonic form long enough to appeal to his reason.
Carter's efforts seem to pay off as Strange sacrifices himself and his demonic half to the collapsing Forge. The Watcher ultimately intervenes, saving Kahhori and Carter. Kahhori is returned to her universe, along with members of her tribe who were also taken prisoner by Strange. It is revealed that Strange's sacrifice successfully restored his universe and Christine Palmer, but at the cost of his own existence, as he was never born into it.
The Watcher offers to take Carter home, which she accepts on the condition that they take the "scenic route." This episode serves as a poignant reminder of the sacrifices made in the name of love and the protection of the multiverse, leaving viewers with a sense of bittersweet victory and the enduring spirit of heroism.
"What If...? Season 2, Episode 9" masterfully concludes with a blend of action, emotion, and the exploration of moral complexities. It stands as a testament to the series' ability to reimagine Marvel's characters and stories in unexpected ways, capturing the essence of what makes the multiverse so fascinating and perilous. As the season draws to a close, fans are left to ponder the implications of Strange Supreme's actions and the future of the multiverse.