Alice touches that head [Volturi] guy…when she touches the [Volturi] guy he “sees” what will happen if he continues his course…OK so the first person whose head comes off is Carlisle. In the vision. Then everything goes to sh-t and all kinds of dying happens. And Bella and Edward kill Aro…After Bella and Edward they die too…all these other people die too. Jane and her brother. Lots of deaths on both sides. Then [Volturi] guy snaps out of it, says he’s sorry. Everybody makes up and lives happily ever after.This provides a more dynamic reason for why the Volturi call off their attack on the Cullens than in the original book, which is pretty much just a lot of people talking to each other.