With our view of God, it can sometimes be difficult to comprehend the actions and thinking of the Greek deities. The Christian God does not tend to take such an active role in the affairs of people's lives, where, on the other hand, the Greeks regarded direct involvement by the gods as a daily, uncontrollable part of life. Needless to say, divine intervention was a major variable in the equation of Homer's Iliad.
The gods picked who they would favour for different reasons. Except Zeus: As the symbol of supreme authority and justice, he makes judgement calls as to the other gods' involvement in the war, remains impartial, and doesn't seem to get caught up in picking favourites. Even when his own son, Sarpedon, was about to die, Zeus chose to let the outcome go unaltered.
On the other hand, Zeus's wife, Hera, displayed the more typical actions of a god.
After Paris, a Trojan, judged Aphrodite the fairest over Hera, and, after her daughter Hebe was replaced as cupbearer to the gods by a young Trojan boy, she was quite resentful towards Troy and its people. Obviously she sided with the Greeks and would stop at no length to express her will. Scheming and manipulating she even dared to trick her husband, King of the Gods. Hera, along with Athena, who was also passed over by Paris, is seen as the chief divine aid to the Greeks.
Being the god of the sea, Poseidon was another strong supporter of the ocean-faring Greeks. Whenever Zeus turned his back Poseidon tried to help the Greeks in the fight. Poseidon felt that he was somewhat Zeus's equal as his brother, but recognizing Zeus's authority and experience, he looked to Zeus as an elder.
There were also Gods who favoured...