Lead in article on Marvel.com about the prelude.In terms of the X-Men and Marvel’s mutants, one of the most important stories building up to HOUSE OF M is the “E for Extinction” arc, which occurred in the pages of NEW X-MEN (2001) #114-116. In that story, Cassandra Nova—the depraved twin of Charles Xavier—used the Sentinels to wipe out Genosha, a mutant nation controlled by Magneto, resulting in the deaths of approximately 16 million mutants. That genocide greatly changed mutantkind, and their dwindling numbers put them on the defensive more than ever before.
Genosha itself played a key role in HOUSE OF M and was the place to which Magneto took Scarlet Witch after “Avengers Disassembled.” On Genosha, Xavier attempted to help Maximoff, though struggled in the task due to her formidable powers. In EXCALIBUR (2004) #14, Xavier went to Doctor Strange for help and, after fighting his way through traumatic visions of his own past, determined that Maximoff and Magneto were two people driven to make their ideals a reality, which gave them a capacity for both great good and evil. Still, Xavier believed redemption was possible for both Maximoff and Magneto. That question about their redeemability informs the very question at the heart of HOUSE OF M and the reaction to it sets the event in motion.