Freud mentions the “compulsion of destiny” as something that “seems intelligible on a rational basis,” (174) or in other words what the ancients called “Destiny” is little more than our inability to break from the habit of “‘perpetual recurrence of the same thing'”(173), our own repressed compulsions manifesting (what Freud calls transference) themselves over and over through the same (or seemingly similar) outlets.
One example (and in keeping with the theme of the ancients) is that of Heracles in Euripides play Herakles. Hercules is a warrior, he has been on numerous dangerous missions (the 12 labors) where his life was in great danger, and in fact he was even in Hades right as the story begins. Hercules has taken the lives of countless men and beasts, he is death and he brings death wherever he goes. Heracles is, in effect, a killing machine.
The play, tragically, ends with Heracles killing his own children in a fit of rage, or what we would now call something akin to PTSD. All the killing he has done, because that is his “Destiny”, causes him to continue to kill, which is his inescapable “Fate”. He repeats the same terrible acts over and over, even against those he loves because he can’t escape this destiny: a repressed compulsion to kill that he tries to keep repressed but which manifests itself in the most terrible ways possible, even against his conscious will and desire.
Hercules wishes he could live a normal life with his family, but he’s doomed to express his repressed “Destiny” (killing) because he has no other outlet and it becomes a compounding issue: the more he kills the worse his PTSD becomes and thus the more he kills. But he was born to kill, not to be a family man sitting at home smoking a pipe and listening to Perry Como on the hi-fi. He can’t repress his desire and though the actions of his desire to kill are terrible to him he repeats them over and over and, in effect, becomes sicker and sicker.