Something that I wonder at, did the absence of Octavian (or if you prefer it, Augustus) will butterflied Roman Empire away...?
As we know, he is such a political genius who successfully (and secretly) turned the decaying Republican state into a new Imperial one...
There are several PODs that I can think of:
-Caesar killed, either in Gallic War or in civil war against Pompey, before he became a Dictator...
In both cases, what would Pompey do to the Republic...? And what would happen to Octavian...?
-Octavian killed, either naturally before the assasination of Caesar or in civil war against Antony...
In first case, who would Caesar pick as his successor, and would that successor succeed in governing Rome...? While in second case, what would Antony do...?
And about the title "Augustus", would in Octavian-less ATL someone will use that...?