Back in the day (a long time ago, before there were humans on the earth, and before any of the sexy gods like Zeus or Venus were born), there was a first generation class of deities called the primordial deities, who weren't really deities in the sense that they were people, but places, elements, and times, like Earth, Air, and Time. They had their own shit figured out- they were self-formed. They just emerged, apparently.
Gaia was one of the first gods to emerge- she was the earth, which basically meant she was the mother of everything that followed. To set the stage, she "did it" with some of the major gods. She got together with Ouranus (Uranus), the god of the sky, which resulted in other sky gods. Mating with Pontus, the god of the sea, gave us more sea gods; and getting together with Tartarus, a hell-pit below the earth, resulted in a race of giants, the Gigantes. Then she also gave birth to us humans through her flesh, but that was later.
As we know about Greek mythology, it's filled with all kinds of drama. First of all, Gaia's main husband, Ouranos (Uranus) was the ruler and king of everything because, hello, he was the sky itself. Together, they had 12 sons and 6 daughters, although this is where the complications start. I guess Uranus didn't like her first two sets of kids, so he locked them away in her stomach, which caused her an enormous amount of pain, pain for which she was ready to avenge as soon as she could come up with a good plan. Her next six kids with Uranus were called the Titans, and as soon as they were old enough, she got them together and asked them if anyone was willing to castrate her husband, Uranus. Kronus (Saturn/Time/EnneagramType 5) was the only one who volunteered, so one day when Uranus is going in to make out with his wife, Kronus comes in and does the ugly deed. He throws his dad's junk into the sea (which eventually gives birth to a lovely maiden, Venus, but not yet.)
So Cronus was the king now, the King of the Titans.
To be continued...