Gaia, also known as Gaea, is the personification of the Earth, the daughter of Chaos, and one of the Protogenoi (the Greek primordial gods). She is also the great mother earth goddess from Greek Mythology. Gaia is the ancestral mother of all life: the primal Mother Earth goddess. She is the immediate parent of Ouranos, from whose sexual union she bore the Titans (themselves parents of many of the Olympian gods), other gods, and the Gigantes (Greek Giants), and of Pontus, from whose union she bore the sea gods.
She also conceived the Cyclops and the Hecatonchires with Ouranos, who later shunned them and hid them in Tartarus, causing her great pain. So Gaia devised a plan. She created a grey flint sickle. And Cronus used the sickle to castrate his father Ouranos as he approached Gaia to have intercourse with her. From Ouranos' spilled blood, Gaia produced the Erinyes, the Gigantes and the Meliae.
When Rhea was pregnant with her youngest child, Zeus, she sought help from Gaia and Ouranos. When Zeus was born, Rhea gave Cronus a stone wrapped in swaddling-clothes in his place, which Cronus swallowed, and Gaia took the child into her care. With the help of Gaia and Chronos' advice, Zeus defeated the Titans and then chucked them in the very depths of Tartarus in a prison of eternal suffering and pain. Upon discovering the fate of her children, Gaia was furious and mad for revenge. She then proceeded to continuously give birth to countless creatures, secretly conceiving a new breed of giants in a cave in northern Greece. But afterwards, Gaia, in union with Tartarus, bore the youngest of her sons Typhon (and his consort Echidna), who would be the last challenge to the authority of Zeus.
Gaia often symbolizes power, chaos and triumph of one individual. The term Gaia is also associated with a recurring Cult throughout the series, namely the Ring of Gaea, and is also associated with the 'Chaos' alignment. While Gaia holds connotations towards nature, creation from chaos, and the earth, along with freedom and worldliness, there are just as many sinister aspects to Gaia in this regard. Gaia's evils include perversion, excess, corruption, depravity, and savagery; just as Gaia represents the earth which all life walks and thrives upon, it also includes the harsh conclusion that all must return to its depths, and that not all it breeds is benevolent.
Gaia is a thief found in the Mazurka Corridor who stole the Silver Relief and is attempting to kill Hecate, the ruler of the area. When Nakajima finds him, Gaia demands that he gives him all of his Macca if he wants the Silver Relief. Once Nakajima pays the thief, he hands over the treasure and runs off.
Black Gaia is the final boss and true antagonist of the game. It is a physical gaia incarnation of suffering and hatred created by the darkness in the hearts of humans and beasts. 2000 years ago it manifested on the fifth planet (the setting of the original game) and began destroying it. Gryas and his allies attempted to stop it but it killed them and destroyed the world, forcing the survivors to settle on the third planet. In current events it has reappeared due to the hatred and sorrow caused by the long war between humans and beasts. Its very presence cause the planet to begin rotting and dying, as shown by all the trees withering. An incomplete form is fought by the party in the middle of the game but it escapes and continues growing in power. It is fought a final time in the underworld created by Larsa and again battles the reincarnation of its ancient enemy Gryas and his friends. This time it is destroyed, but its implied it will eventually return as long as there is both gaia and evil in the hearts of humans and beasts. Gaia can be hatched from an Egg, received from an old man in Elba, after beating the game.
The Gaia demon can be found as a rare encounter in the deepest area of the Abandoned Factory. After being defeated, Gaia drops the Cradle of Creation Material Card, allowing the player to summon her as a Persona in the Velvet Room. Upon being defeated once, the demon form of Gaia can't be encountered again.