On the other hand, having Cleopatra and Octavian form some sort of friendship around this time (and nothing beyond that) would be pretty interesting in itself. Same age, similarly shrew, I don't see a particular reason why the two should hate each other. I don't think anyone ever seriously entertained the idea of Caesarion inheriting anything outside Egypt, while Octavian was far from knowing he was to be Caesar's heir at this point. How would the next round of civil war play out? Assuming Octavian still wins, does he keep Ptolemaic Egypt (first ruled by a friend, later by his "brother") around, as a personally ally of his? Assuming the republic doesn't turn into the empire, having a foreign kingdom personally loyal to you (rather than Rome) could be quite a nice bonus.