As the king, Gilgamesh was 1/3 human, 2/3 god, and was very mean and frightened his people. The people prayed to Anu, the sky god for help.
Anu sent down a beast named Enkidu, to roam the forrests.
Me! marry you? that is the stupidest thing I have ever heard!!
Gilgamesh heard about Enkidu and sent a women to use as bait and train Enkidu, and the women then brought Enkidu to king Gilgamesh as a new man, but Gilgamesh still thought of him as beast so he wanted to fight.
Time to be imortal
So Gilgamesh and Enkidu fought and fought. Gilgamesh soon won, Enkidu accepted it and they became the best of friends. They went out together to the cedar forest and killed the beast that lurked there.
When they returned, everyone was congragulating them. Ishtar the godess of love, wanted to marry Gilgamesh, but he refused and teased her. This made Ishtar mad, so she sent the bull of heaven to destroy Gilgamesh and the village. Gilgamesh and Enkidu killed the bull of heaven. Enkidu got sick as punishment for killing the bull.
Gilgamesh was forgiven because he is 1/3 human and 2/3 god. Soon after Enkidu passed, Gilgamesh started to search for eternal life because he new he would also die someday. The only way for Gilgamesh to be imortal was that he had to leave his civilization behind. So he did.