Athena vs Poseidon
These two always seemed more or less in squabble with each other. Wasn't it Athens so was it Odysseus or Perseus or some other hero Athena was helping.
Probably because they were both powerful, stubborn and energetic and none of them were used to back down and give some other person an advantage. And when they met someone else who didn't back down they were unused to it and whatever diplomacy they had aquired went out the door.
And to be true, most of the times - well all I guess - I found myself rooting for Athena...