Homer uses Odysseus' stability and maturity as a foil to both Achilles and Agamemnon. There is no character development in Odysseus, but his purpose in the Iliad does not call for dramatic character development. His purpose is to show us strong demonstrations of tact, strategic ability, and heroic capability, all of which are qualities that a king should have. Additionally, Homer also shows Odysseus' ability to advise. Above all, Odysseus exhibits self-control, and a lack of self-control is alarmingly apparent in both Achilles and Agamemnon. It is also obvious that Odysseus has greater kingly qualifications than Agamemnon because his decisions are almost always sound and successful when followed. He is always rational and diplomatic.
For example, as one of Agamemnon's ambassadors to Achilles, Odysseus presents Agamemnon's offers. But when Achilles refuses to accept the offers, Odysseus does not argue with Achilles. He knows that arguing with Achilles is useless, and by arguing, he may defeat the purpose of the mission and force Achilles into an even stronger position of alienation from the Achaian forces. Further, when confronted with Achilles' angry desire to rush into battle after the death of Patroklos, Odysseus calmly argues that the army must eat first. Homer almost always refers to Odysseus as the "great tactician" and it is Odysseus who eventually comes up with the stratagem of the Trojan Horse that wins the war.
As a foil to both Achilles and Agamemnon, Odysseus' ability to remain calm and analyze a problem stands out boldly against both men's quickness to anger and their inability to resolve their differences tactfully.
By continually supporting order over disorder, Odysseus acts as a stabilizing factor in the Iliad, and even Homer's comments about Odysseus' cunning do not detract from his heroic stature.