I do wonder if what Paul is dealing with, in terms of the twins, is the Golden Path approaching, and him dealing with what that means for him. He took the Water of Life because he didn't think he could win without it, and thus brought the jihad. But, now with it, the Golden Path is revealed to him. I absolutely think that is part of Children that Villenueve would bring into Messiah. Its sort of retconned onto him in Children, so why not add those elements to Messiah. And I almost wonder if Leto and Ghanima are going to be different sides of arguments as to what he should do about the Golden Path.