The Epic of Gilgamesh is one of the oldest ones in the book, one of the oldest stories written by the human race (that people these days care to remember, anyway.) It's a story that's been told time and time again throughout the millennia; a tale of pride, of redemption, of man's eternal struggle against his own nature, and his acceptance of his place in the universe.
Gilgamesh is the great king of Uruk. Wise, robust, unbeatable in combat, half-divine, one of the mightiest rulers in the entire world. But he's also arrogant, egotistical, and cruel to his subjects, who cry to the gods for relief. And so the gods send Enkidu, a wild man formed from the clay of the Earth, to end his reign of terror and teach him his role. But rather than defeating Gilgamesh through force of arms, he befriends the great king, and the two of them become as close as brothers. Together, they defeat all the horrors the gods can send at them - the terrible giant Humbaba, the rampaging Bull of Heaven, and the other monsters that history has forgotten or are now known by other names. In the end, the gods decide that Enkidu must die for his failure, and despite Gilgamesh's love and the ministrations of his healers, he slips away.
The bereaved king becomes obsessed with his own mortality, and searches the world for a way to cheat death. He travels far and wide before he meets Utnapishtim, the oldest man in the world, the only man to ever become immortal, and is humbled by him - for when the wise man challenges him to remain awake for seven days, he cannot even conquer sleep, let alone death. Utnapishtim relents and tells him of a single plant which can grant him unending youth - but after diving to the bottom of the sea itself to acquire it, it is stolen away from him and eaten by a snake.
Thus the tale ends, with Gilgamesh accepting his mortality and returning to Uruk to rule as a kinder, humbler lord. That's how the version that's known today ends, anyway. I went to great lengths to ensure that the last few tablets were never rediscovered by anyone smart enough to piece things together. The truth is, Gilgamesh learned from Utnapishtim that there is a balance between life and death. For a man to live longer than his allotted time, others must have their lives cut short. For a man to live forever… well, it took years for Gilgamesh to figure out the techniques and teach them to those of his priests who were loyal enough, but in the end, he learned the secret.
At first they took the old and the sick to the sacrificial altars. Then the children, babies torn from their mother's breasts and thrown onto the pyres. Then the women - especially the virgins - who suffered untold depredations as the priests of Uruk snuffed out not only their lives, but their souls. Soon, anyone who showed their face on the streets of Uruk was fair game for those who served only out of the hope that they would be taken last. In the end, they were forced to turn on each other. The work was finally completed when the last two of the elders slit each others' throats while singing a song of praise to their new god. Gilgamesh would live forever - as king over a city populated only by the dead.
None could stop the great king as he tore a swath of destruction across the world with his new-found gifts. Entire armies fell before him, city walls crumbled at his coming. No man could defeat him - and even if he were cut to pieces and seemingly killed, he simply rose and returned again, bearing the scars of his defeats proudly as he hunted and annihilated those who had dared to stand before him. He sought not wealth, nor women, nor even worship or adulation from those he conquered - he did it because he could, and because it pleased him to do so. He always sought a greater challenge.
And the gods answered his challenge. They sent Enkidu back - for even from the land of the dead, he saw what his friend, his companion, his brother, had become, and could not abide it.
To bring the dead back to life is a difficult thing even for a god, of course. He was not as he had been - they couldn't find all his pieces and had to replace some of them with iron and bronze, and none who looked upon him could doubt that he was not a natural man. They granted him two divine boons to ensure that he would complete the task he had failed at before. First, a curse - that he could never stay long in one place and become idle, for a pestilence would follow him and the men of the land would not abide his presence, nor would he find any food to eat. Second, a blessing - that no man or god, not even Gilgamesh, could harm him without harming himself.
The battle between them would have been a story told by people the world over - if any who witnessed it had lived. Entire empires crumbled around them as they grappled - great Al-Ilas with its silver spires, the city of Vemura and its fabled seven citadels, and I seem to recall that even the land of the Devas did not long endure when the battle found its way into their realm. The battle might have been the doom of all mankind itself - but on the dawn of the seventh day, in the seventh month, in the seventh year of their fighting, Gilgamesh struck Enkidu harder than he could bear, and when he felt the pain he had dealt to his brother, he fell.
"Let me go, my brother," said Gilgamesh, "for the day has broken, and I can fight no more."
"I cannot, my brother," Enkidu replied, "unless you shall let me bind you until the day the world is undone." And though it pained Gilgamesh to do so, his love for his brother was so great that he relented.
And so Gilgamesh was bound and sealed away, to wait until the day when he would face a power great enough to defeat him once and for all. As for Enkidu, the gift the gods had given him could not be surrendered, and he has wandered ever since. The story of the two brothers passed from history into legend, and Enkidu made sure enough of the details got forgotten that nobody again could do what his brother had done. In time, even the names got changed around. Enkidu would be known by many names over the years as he came and went; Osiris, Lazarus, Wandering Jew, St. Germain, and so on.
I'm pretty sure my name never really was Enkidu to begin with, though.