Andy Smith, in "Achilles and Gilgamesh," confirms that the deaths of friends change these protagonists. Achilles undergoes his emotional shift through the death of his best friend Patroclus; Gilgamesh does the same. However, Patroclus is only Achilles' friend; Enkidu is also a true foil, who reveals the weaknesses of Gilgamesh. Enkidu is made human through week-long sex with the priestess Shamhat; as a result, he develops a moral character and protests Gilgamesh's own sexual habits. Also, prior to the battle with the ancient monster Humbaba, Enkidu gives Gilgamesh the courage he needs to fight. Enkidu, unlike Patroclus, fills Gilgamesh's void.
Gerald Gresseth, in "The Gilgamesh Epic and Homer," points out that since Enkidu is humanized by Gilgamesh, Enkidu's death gives Gilgamesh more humanity. Also, in his translation of the Sumerian epic, Stephen Mitchell notes that the gods find Humbaba's slaying unnatural, and the death of Enkidu is punishment for disrupting the natural order. Just as his living fulfills Gilgamesh, so Enkidu's dying enhances the motivating power and character of the Sumerian hero. Gilgamesh changes not just because Enkidu dies but because the gods demand it.
The teller of the epic prepares the reader for Gilgamesh's sea change long before it occurs. In Book 1, when Gilgamesh learns of the wild man Enkidu that he must tame into a friend, he sends no army to conquer him but a sexually skilled priestess. It is the first time he is wise, using strategy rather than force. Also, in Book 4, on the night before the slaying of Humbaba, the hero feels fear as five death dreams play themselves out. Each dream presents Enkidu as Gilgamesh's savior; thus, armed with this knowledge, the hero meets the beast with a stout heart. After Enkidu is killed, Gilgamesh has already become his own savior. The change is both bad and good: Gilgamesh loses his intuitive twin but gains his own self.
Gilgamesh at the epic's beginning is the height of arrogance, destroying his surroundings, offending his deities and wreaking havoc among his subjects. By the time Enkidu is dead, Gilgamesh matures wholeheartedly: his changes include a search for eternal life and an appreciation for his city. He has certainly reformed, but readers have been prepared for the change from the epic's beginning.