Doctor Strange in the Multiverse of Madness designates the Scarlet Witch as its primary antagonist, as Elizabeth Olsen's formidable magic-wielder redefines the Marvel Cinematic Universe's portrait of villainy. Otherwise known by the name Wanda Maximoff, the Scarlet Witch appears in Multiverse of Madness having harnessed Chaos Magic and committed to reuniting with her sons Billy and Tommy in another universe following the events of WandaVision.
Influenced by the Darkhold book, Wanda pursues America Chavez (Xochitl Gomez) in Doctor Strange 2 for her ability to travel the multiverse, as Doctor Stephen Strange (Benedict Cumberbatch) strives to protect America and locate the Darkhold's antithesis, the Book of Vishanti. The Scarlet Witch's willingness to massacre those in her way superficially labels her as a villain, though beneath her brutality lies so much more.
Prefacing her transformation into the Scarlet Witch, Wanda's backstory is plagued by trauma and grief. Orphaned in Sokovia at the age of 10 when their parents were killed by a series of bombings, Wanda and her twin brother Pietro later joined HYDRA — who experimented on their superhuman abilities and augmented Wanda's powers using the Mind Stone. Wanda and Pietro entered the MCU as antagonists in Avengers: Age of Ultron, united with the genocidal robot Ultron on their disdain for Tony Stark. The twins switched sides upon learning of Ultron's ill intentions and fought with the Avengers, though at the cost of Pietro's life. Wanda then began a romance with Vision, which ended devastatingly. The events of Avengers: Infinity War forced Wanda to destroy the Mind Stone embedded in Vision's head to keep it from Thanos.
Although Wanda fell victim to Thanos' Snap, she returned five years later in Avengers: Endgame, joining the decisive battle against the Mad Titan. Alone with her grief, Wanda then created a makeshift reality in Westview, complete with Vision and their children. Upon learning of the pain her subjugation inflicted upon the town's residents, Wanda dismantled the anomaly. At WandaVision's culmination, Wanda recovered the Darkhold from Agatha Harkness and fulfilled her destiny as the Scarlet Witch — an immeasurably powerful mythical being prophesized in the book.