In general, the gods in this story are depicted like regular people, only immortal and with superhuman powers. They have all the sorts of emotions (especially negative ones) that we associate with people.
Look, for example, at Apollo's behavior in Book 1 of this epic. Apollo is offended because one of his priests has not been shown sufficient respect. This shows us that Apollo is protective of his honor -- he wants people to treat him with the respect he deserves.
What does Apollo then do? He takes revenge. He starts killing the Achaeans' animals and then he starts killing the people themselves. He is doing this simply because he has been offended.
Examples like this show that the gods in the Iliad are no better than people -- they have the same negative emotions and are just as violent as the people.