What is the relationship of Athena and Poseidon?

I think that they are rivals. They fought over which god would Athens be dedicated, so Zeus had them give the gifts. Athena was chosen. This generally, made Poseidon angry. Though you also have to take into account, that chariots were a work of the both of them. Poseidon created horses. And Athena created the chariot itself. Of course you could say since Athena is the goddess of wisdom that she just used what tools were most available and useful. These are my points on the matter. Someone else may have more proof. Or just a better understanding of Greek myths.