Does Poseidon know what will happen to Percy (Jackson)?

My father once told me that I shouldn't have been born and I was a mistake he made and he never wanted me born as a hero's life is never happy. In the 5th book Prometheus told me that my father knows what would happen to me should I turn 16. The prophecy fooled everyone and the hero wasn't me but was my father talking about Hera taking me away from the Greeks and not the prophecy? ""Not yet, perhaps,...Not yet" - that's that he said