Anyone else starting to see REALLY prominent Mephisto features in the "new Diablo"?
Page 26 and 27 of The Book of Cain along with the cover of the book (!) are starting to really strongly suggest Mephisto's leadership/tactician roll has him as the true villain. I'm thinking that in the context of D3, his brethren are weapons in a new war fought ON Sanctuary with Nephalem vessels as the prize.
Leah may indeed be the part-demon daughter of Diablo (The Wanderer), but I'm starting to believe it is Mephisto who will possess her when events in D3 cause her hatred to manifest and lose control.