I have a feeling there was some serious late in the game re-writing going on. Why name Rachel McAdams Antigone if she isn't going to be involved in the Oedipus aspect of the story? Why involve Caspere, Pitlor and Chessani with Antigone's father and the commune at all? It didn't advance the plot. It was just another stupid coincidence in a story that already had way too many.
I suspect the backstory to the main plot went something like this:
1. Antigone and her brother are the kids at the jewellry store robber. They are both Caspere's illegitmate kids.
2. The cops who did the robbery on Caspere's orders find the kids and rather than kill them they drop them off - Ani at the commune, Brother at a foster home
3. Ani gets raped at the commune, leaves and becomes a cop working for Vinci
4. Early in her career she has a relationship with Caspere because he is powerful and she has repressed issues
6. Her brother has been investigating the parents murder his entire life (he is a few years older).
7. He kills Caspere
8. Ani is the cop working the case and she uncover all of this over the course of the season
I suspect the backstory to the main plot went something like this:
1. Antigone and her brother are the kids at the jewellry store robber. They are both Caspere's illegitmate kids.
2. The cops who did the robbery on Caspere's orders find the kids and rather than kill them they drop them off - Ani at the commune, Brother at a foster home
3. Ani gets raped at the commune, leaves and becomes a cop working for Vinci
4. Early in her career she has a relationship with Caspere because he is powerful and she has repressed issues
6. Her brother has been investigating the parents murder his entire life (he is a few years older).
7. He kills Caspere
8. Ani is the cop working the case and she uncover all of this over the course of the season