Scott basically went public with the fact that the Terrigen Mist was killing mutants. This led to a massacre of several hundred Inhumans by evil mutants orchestrated by Quentin Quires using the Hellfire Club's resources.

In the ensuing madness, Teen Jean tried to seize control over Scott's mind and reprogram his brain to rid him of EVERYTHING Rightclops related. Scott responded by unleashing the Void sliver from his brain into Teen Jean's which basically mindraped her so badly, she quit being a super-hero and went into hiding.

The thing that Brevoort is claiming will REALLY upset fans, is the big reveal that Quentin is now a mass murderer and that the bulk of the Yost/Aaron/Generation Hope Jr X-Men are now his "Marauders". Idie is not part of the group, and a major part of the An-AD book will be Idie, Laura, and the rest of the Teen X-Men fighting Quentin's plans to kill all of the Inhumans.

Similarly, the Magneto X-Men team in Uncanny X-Men is going to be working with Scott in secret.

Source: /co/