I wonder just how truly personal Octavian’s vengeance was. If you look at the timelines, they had very little time together. Octavius was 4 when Caesar went to Gaul and 13 when he crossed the Rubicon. After that, Caesar spent precious little time in Rome, where he might have interacted with the boy. He asked for Octavius to join him in Africa, but Atia said he was too young. He finally joined Caesar in Hispania at the age of 17 (or thereabouts). They spent a great deal of time together on the way back to Rome, but after that Octavius soon went off to Greece. Unless you want to credit Antony’s alleged accusation that Octavius “bought” his adoption with sexual favors, there seems little time for them to have formed a close personal bond.

So what might have driven Octavian’s apparent thirst for total revenge? He spent much of his childhood in the home of his grandparents, and his grandmother was Caesar’s sister. He must have heard a lot about Caesar from her, particularly since Caesar was busy making a name for himself in Gaul. This strikes me as a prime breeding ground for hero worship.

He spent the rest of his childhood and youth in the home of his stepfather, Lucius Marcius Phillipus. Phillipus was a supporter of Caesar, but he seems to have tried to avoid any sort of conflict. He even bowed out of the civil war. Atia was said to have been a very religious woman (she rather looks the part) and the ideal Roman matron. This would no doubt also have had some impact on Octavian’s patterns of thinking.

Given the above and what we know of Octavian’s rather strong traditionalism and belief in the old Roman moral code (at least where women weren’t concerned), he would probably have seen it as his duty. Under Roman law and religion, his adoption made him the equivalent of Caesar’s biological son. This gave him a number of obligations toward Caesar and his memory, including vengeance, and Octavian fulfilled them all with a disturbing thoroughness.

The obligations of tradition? Definitely. A personal matter? Perhaps less so; I just don’t see a window when such a relationship could have formed. Revenge for a hero? Possibly. Politically advantageous? Oh, yeah, but that may have just been icing on the cake.