Poseidon was a very different kind of god to Hades. He could be as truculent, stormy, vain, capricious, inconsistent, restless, cruel and unfathomable as the oceans he commanded. But he could be loyal and grateful too. In common with his brothers and some of his sisters, he was also to exhibit urgent bodily lust, deep spiritual love and every feeling in between. Like all the gods, he was greedy for admiration, sacrifice, obedience and adoration. Once your friend, always your friend. Once your enemy, always your enemy. And he was ambitious for more than burnt offerings, libations and prayers. He always kept an eager, avaricious eye on the youngest of his brothers, the one who now called himself 『eldest』 and 『king』. Should the great Zeus make too many mistakes, Poseidon would be there to topple him from his throne.
The Cyclopes, just as they had forged thunderbolts for Zeus, now created a great weapon for Poseidon too – a trident. This massive three-pronged fishing spear could be used to stir up tidal waves and whirlpools – even to make the earth tremble with earthquakes, which gave Poseidon the soubriquet 『Earth Shaker』. His desire for his sister Demeter caused him to invent the horse to impress and please her. He lost his passion for Demeter, but the horse remained sacred to him always.
Under what we would now call the Aegean Sea, Poseidon built a vast palace of coral and pearl in which he installed himself and his chosen consort, AMPHITRITE, a daughter of Nereus and Doris, or (some say) of Oceanus and Tethys. As a wedding gift, Poseidon presented Amphitrite with the very first dolphin. She bore him a son, TRITON, a kind of merman, usually depicted sitting on his tail and blowing with bulging cheeks into a large conch shell. Amphitrite, if truth be told, seems to have been rather colourless and appears in few stories of any great interest. Poseidon spent almost all his time pursuing a perfectly exhausting quantity of beautiful girls and boys and fathering by the girls an even greater number of monsters, demigods and human heroes – Percy Jackson and Theseus to name but two.
Poseidon’s Roman equivalent was NEPTUNE, whose giant planet is surrounded by moons that include Thalassa, Triton, Naiad and Proteus.
Which is strange, as naiads, of course, were freshwater nymphs, unlike the salty Nereids and Oceanids. Perhaps the astronomers in this case failed to consult a classicist before allocating names.
PROTEUS, the shape-shifting Old Man of the Sea, herded sea-beasts and knew much. To get information from him you had to wrestle him, which was tricky as he could quickly and frustratingly change himself into any number of new shapes – from lizard to leopard, from dolphin to dormouse. From this slippery ability we get the word 『protean』.