There are three paths in the game that are flagged : Green emperor, where Cas and her family and the western provinces gain majority control over the crown "obviously, because she and her family organized the entire plot". Red Emperor, kill cass just before the coronation opens the conquest paths for the rest of the provinces. White Emperor, which is the golden order/status quo pass where maybe the rest of the regions join through diplomacy (you have to defeat cass coup but not kill her).