Even though Patroklos is an important character in the Iliad, Homer gives little attention to him until the ninth book, and even then, the focus is not on Patroklos himself, but on his relationship to Achilles. In fact, one rarely sees Patroklos as an individual. There is no dramatic character development, but one does see Patroklos as a character perpetrates dramatic events and provides a clearer understanding of Achilles. Patroklos' main purpose in the Iliad is to bring Achilles back into the war. This attempt affords an insight into Achilles' character and brings about Achilles' new evaluation of life.
Although one sees Patroklos' strengths and weaknesses (his "aristeia") during his battle scenes, Homer uses him primarily to move the plot along and to highlight the actions and thoughts of other characters.
Achilles and Patroklos have a particularly close relationship, based partly upon the heroic code of warrior-companion and partly upon Patroklos' role as an advisor to Achilles. While certain customs must be followed in such relationships, the spirit of the code is of greater importance to these two warriors. Homer demonstrates the heroic and familiar love between the two men and the obvious bond of mutual respect extending beyond the warrior-companion relationship.
Patroklos makes no speeches in the Iliad. When he and Achilles are together, before Agamemnon's ambassadors arrive, Patroklos waits for Achilles to finish singing before he begins speaking. When Agamemnon's agents arrive, Patroklos silently mixes drinks, and then both he and Achilles work together as equals to prepare a meal for the guests. Each one seems to understand the thoughts and desires of the other. It is as though Patroklos is Achilles' alter ego, or "second self," an idea that carries over into Patroklos' aristeia.
Later, after Patroklos has returned from Nestor's camp, his deep sensitivity to the Achaian losses and the death of his friends is apparent. When he asks Achilles' permission to enter the war, Achilles compares him to a "silly little girl," and while Achilles' comment underscores Patroklos' obedient sensitivity, it also indicates Patroklos' dependence upon Achilles and shows a strong emotional bond that activates Achilles' wrath after Patroklos' death. But the emotional interdependence between the two men does not prevent Patroklos from criticizing Achilles' anger, and at one point, asking who can cure Achilles' consuming wrath. Patroklos even tells Achilles that he hopes that he himself is never cursed with such anger.
Patroklos may be, in a sense, Achilles' alter ego, or "second self," but his error is in believing that he can perform as brilliantly as Achilles on the battlefield. When he puts on Achilles' armor, he tries to assume Achilles' identity, and as a result, he tries a feat that is beyond his own strength. That is, Patroklos tries to lead the Achaian attack on the city of Troy, despite the fact that Achilles has warned him not to attempt to do anything except protect the Achaian fleet of ships.
In three drives into the Trojan front, Patroklos kills nine men in each drive, but on the fourth drive, Apollo strikes him across the back, sending him into a daze and making him vulnerable to Hektor's attack. As Patroklos is dying, he is aware that he is a scapegoat and that it was not Hektor, but Apollo who was his "deadly destiny," because Apollo inspired him to attack the wall even though Achilles had instructed him specifically not to do so. Patroklos thus realizes that by taking Achilles' place in battle, he has become the means by which Achilles' return to the war is assured. He reminds Hektor that "death and powerful destiny are standing beside" him. Destiny, then, guides Patroklos from the moment he enters the war.
After killing Patroklos, Hektor deviates from the code of honor by threatening to give Patroklos' body to the dogs. Patroklos' death thereby leads to the deaths of both Hektor and Achilles in the sense that both dishonor Greek ideals by threats and acts of desecration.