The history of Greek Mythology is complicated, with the world being made from nothing and a prophecy causing a father to eat his children to a 10-year war resulting in one side winning with the help of 100-armed giants and cyclopes. To help simplify the complexity of this tale, let me guide you the main story of the Greek family tree.
Let us start out by looking at the origin of the gods.
The First Age: The Creation
In the beginning, there was Chaos, literally. Chaos was the God of Nothingness. In him was everything, but it had no form; it was just there. Somehow, Chaos split into five forms: Erebus (Darkness), Nyx (Night), Gaea (Earth), Tartarus (The Underworld), and Eros (Love). Gaea was made of all the material of Earth: rock, water, and air. Tartarus was the life force of Chaos. Eros was the attraction of all the materials from Chaos. Erebus and Nyx were the empty remains of Chaos. This was the Age of the Protagenoi. Protagenoi are the actual Spirits of the Elements. While the other gods controlled the elements, the Proteagenoi were the original life forces of the elements.
The Second Age: The Time of the Protagenoi
Erebus and Nyx felt the powers of Eros and fell in love. The result of this love are all the evils in the world that would be trapped in a box that Pandora would open. This includes Death, Disease, Old Age, War, Famine, and The Fates. However, the two children that did not get trapped were Aether (Brightness) and Hemera (Day). These two also fell in love and challenged their parents for dominance in the Sky. This battle resulted in the creation of Day and Night, both chasing each other for control over the Sky.
The Sky, named Ouranus, was created alongside Pontus, the ocean, when Gaea organized the elements with air ascending upward and the waters filling in the low spots of the earth. Gaea got jealous of the amount of children that Nyx and Erebus had and chose her son Ouranus to be her husband. Together, their love transformed into 12 children, titled Titans by their father. And they were happy for a time.
The Fates made a prophecy that each son will kill their father for power. Ouranus grew fearful of his children after this; each child with amazing abilities and strength. This fear gave birth to the first three Cyclopes, giants with one single eye and master craftsmanship skills. Seeing his new children, Ouranus grew mad. This madness gave rise to the Hecatoncheires, giants with 100 arms and heads. Ouranus cried out in fear and began to threaten his own children. Fearful, all 18 of the children ran back to their mother for protection. Gaea, sad and angered, cursed Ouranus and began a plan for revenge.
Gaea made a scythe and looked to her children and told them that the child that will slay Ouranus will become the Ruler of All Realms. It was Kronos, the youngest of the Titans, that took the scythe and originated the plan to kill Ouranus. After an ambush and chaining Ouranus, Kronos took the scythe and castrated his father. Ouranus bled out and entered a coma, but was supported by Gaea at the ends of the world. His blood made the Furies and all the nymphs (nature spirits). Thus began the Age of the Titans.
The Third Age: The Golden Age of the Titans
Kronos took the World as his own and became the Titan of Time. Kronos only wanted beauty in his new world, so he sent his siblings the Cyclopeses and the Hecatoncheiresto Tartarus to live there in punishment for not looking like normal Titans. He married his older sister Rhea and was happy. His other siblings had children and everything was peaceful. Until Rhea confronted him and told him that she was pregnant with six children. Kronos then followed his father's footsteps and went insane. When Rhea gave birth to a healthy girl, Kronos decided to remove the child from the world by eating her. Rhea gave birth four more times and Kronos ate the other four children. Fearful for her last baby, Rhea was taken to a far off island by Gaea and gave birth to her last child and gave a rock to Kronos as a substitute, which he ate. Kronos grew calm and rested, his stomach full of flesh and stone.
Many years later, a full grown Titan decided to free the children in Kronos's stomach by poisoning him. Kronos vomited his children, now fully grown, and gave praise to their savior. Rhea ran off and hid her children from their sick father and introduced each one. She named them Hestia, Poseidon, Demeter, Hades, Hera and the one who saved them as Zeus.
Zeus led his siblings and a few of the other Titans to war against their parents. The war lasted a full decade as both sides were evenly matched in power. One day, Gaea told Zeus about his imprisoned uncles and led him down to their prison. Zeus freed his uncles and led them to the battlefield. Thankful, the Cyclopes and the Hecatoncheires sided with Zeus. The Cyclopes made each of the children a special weapon, including the trident and the lightning bolt. This allowed the siblings to win against their parents. In victory, the children banished their parents to Tartarus. They claimed their home on Mt. Olympus and called themselves the Olympians.
The Fourth Age: The Immortal Age of the Olympians
The three sons of Zeus drew straws to see which area to claim as their own. Zeus won and claimed the Sky, Poseidon took the Sea, and Hades was left with the Underworld. Zeus took Hera as his wife, but produced a child with any woman he saw, leading to hundreds of minor gods and demigods as the children of Zeus, including most of the Olympic Council. The gods that ruled until man's betrayal are Zeus, Poseidon, Hermes, Dionysus, Hephaestus, Ares, Apollo, Hera, Demeter, Artemis, Aphrodite, and Athena as the 12 Olympians, Hestia as the Guardian of the Home, and Hades as the Judge of the Dead.
The Fifth Age: The Current Age of Man
Prometheus created man, but was punished by giving man the gift of fire. Man worshipped the gods until man saw no need to worship them for protection. For punishment and to stop the prophecy of the son killing the father for power, Zeus gave the box containing the world's evil to Pandora, the Queen of mankind. She opened it and cursed mankind. Still, man managed to defeat the gods and lay claim to the world.
Each god has their own story and power, but it always goes back to an Olympian interacting with some other being. The stories of the gods of old are fun and interesting. And there is enough for each individual to connect with; just explore and find comfort in knowledge.