Warning: Spoilers for Doctor Strange in the Multiverse of Madness ahead.
In Doctor Strange in the Multiverse of Madness, WandaVision's Billy and Tommy become integral to the fate of reality itself, and their existence in Earth-838 is a clue at just how much power resides in the Scarlet Witch of prophecy. Indeed, the inclusion of Billy and Tommy in the Doctor Strange 2 cast is Wanda's primary motivation for nearly tearing apart all of reality. However, these boys are technically not the same twins that were featured in WandaVision.
Wanda Maximoff gives birth to Billy and Tommy inside the WandaVision Hex, which Wanda created through Chaos Magic so she can live out a fake sitcom-like reality inside the town of Westview. After dealing with Agatha Harkness, Wanda disables the Hex, releasing Westview's residents and forcing Wanda to say goodbye to her entire family, including Vision. The post-credits scene shows Wanda living in a remote cabin and studying the Darkhold. Wanda hears the familiar voices of Billy and Tommy asking her to help them, causing her eyes to glow, which is how WandaVision ends. After being corrupted by the Darkhold, Wanda attempts to kidnap Billy and Tommy from an alternate universe in Doctor Strange in the Multiverse of Madness, ultimately leading to Scarlet Witch's death at her own hands.
Related: WandaVision Ending Explained: Biggest Reveals & MCU Future Setup
Doctor Strange 2's Wanda death scene not only implies that no one but Scarlet Witch can truly destroy herself, but it also punctuates the movie's temporary conclusion to Billy and Tommy's fate. Wanda finding the twins under the care of an alternate reality version of herself in Earth-838 — the same family she created from her own imagination —
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