Zeus and his brothers didn't always get along growing up, especially after Zeus overthrew their father to take over Paradise. Hades hated that he was thrust into the Underworld to lead over the souls of the damned while Poseidon got to roam freely from sea to sea. Posi got bored quickly as the humans who managed to catch a glimpse didn't really care that he was there. All anyone cared about were Zeus and his daughters.
Once the gods began interacting with the races of humanity, Zeus created the Nova Universe with Nexus, Exteria, and Solstice. The people loved him for it. Things were finally moving toward peace so he decided to rest. He thought by choosing Athena his brothers would be able to do whatever they wanted, wherever they wanted. Hades was married to Persephone and he thought Posi was happy living freely.
He was wrong but Athena was able to see things from a different perspective.
