Zeus was the only sibling in his family that didn't get swallowed by his father Cronus. His mother tricked his father into swallowing a rock instead... Ouch! When Zeus grew up he freed his brothers and sisters and declared war against his father and the Titans. The Cyclopes joined Zeus and his team. Eventually, Zeus and his siblings won. They were standing on Mount Olympus and thus after they were called the Olympians. Zeus became King of the gods and goddesses.
Before Zeus freed his siblings, and while Hades was still in his father's stomach, he beat his father's liver and was thrashing around in there... talk about major stomach pains, am I right? After he was freed I guess Hades was grateful, but not, at the same time? It's because by then Hades had gotten used to the darkness and didn't like the daylight, but he did want to be free. So, when the Olympians won, he claimed the Underworld where he could live in darkness.
Poseidon adored being in the water. He fell in love with Medusa, the snake haired Gorgon, and married her. Pegasus was their child. When anything mortal looks into Medusa's eyes, they will immediately be turned to stone. Poseidon became god of the seas, and carried a trident, which many people would recognize from Disney's, The Little Mermaid.
Athena is the goddess of wisdom. She came out of her father's forehead fully alert and completely wise. She had grey eyes and took her place as one of the gods and goddesses of Olympus. She was always ready to give wisdom to the stubborn, and help strategize with warriors.
Perseus was not an Olympus god, but was a hero. He beheaded Medusa which freed Pegasus and Chrysaor. He also saved Andromeda, the daughter of the vain queen Casseopia. He told Andromeda's father, the king, that he would kill the sea monster if the king would give his daughter to him in marriage, and the king agreed. So Perseus killed the sea monster and married Andromeda.
For a quick overview of the gods and goddesses of Greek Mythology, we've included a quick guide below: