Father Dagon and Mother Hydra were not included in the Bible of Cthulhu. And after what I have whispered in my mind (in the same way that I learned about R'lyeh in my dreams from Dagon) what they represent, and I found that they are very important beings.
Father Dagon and Mother Hydra is said that they live at the bottom of the ocean at the great city of Y'ha-nthlei.They had their children.We call them today as deep ones.
Dagon with his wife and children were discovered by a man called Yalakeia at a mysterious Island.He created a religion that it is known today as The Esoteric Order of Dagon.Obed Marsh after so many years found this Island and he brought it, to the city of Innsmouth, freeing finally Innsmouth from Christianity.The Deep Ones started to work with the Innsmouth people, and at the end they took the final oath of Dagon and they started to getting married with the deep ones.They rised children that they looked as people but at the end they were becoming a deep one and returning back to the sea, to Y'ha-nthlei, to his mother and father.The mosy scary and sacred place of innsmouth was the Devil's Reef, that the Marsh family were Summoning the deep ones and sometimes Dagon himself to give him sacrifices.He was giving them plenty of fish and gold for that.
Let's analyse this quick story.Let's go back a long journey in the past......were all life began. Every living creature we know was born to the ocean as monocyte organism. After mullions of years these Monocytes got outside from the water. They started to getting shape. They became living creatures as birds, lizards, dinosaurs....humans. We all came from the sea.Dagon and Hydra live to the ocean.They are the powers of the sea.Dagon is for males and Hydra for females.We are all children of Dagon and Hydra.It is with these knowledge that we can transform to a deep one.This transformation represents enlightenment, ascension, realisation. With these knowledge we can understand were all came from.