Zeus is the god of the heavans and thunder. Him being the ruler of the earth was friend of princes and would protect them with his advice, he is also the protecter of the other earthlings.His symbol is the lightning bolt.
Poseidon is the god of the sea. He would make new land and there would be slow tides when he was happy but when he was mad he would make high tides and would shipwreck and drown people. His symbol is the tridont.
Hades is the god of the underworld. when he got lonely one day he decides to kidnap persephone who now rules over the underworld. His symbol is a spepter.