From my research, I have determined that this is a portrait of the fisher king himself. He is clothed in a strange manor, being both fancifully dressed as is clearly visible in the cuffs and collar of the shirt, yet he wears an unadorned dress looking item of clothing. We see him going down to the river in order to fish - because his land won't bear fruit due to the whole genital/leg (depending on the version) injury. This has caused the land to be infertile, so they must fish for food. We can see a clearly marked castle in the background which further tends to indicate a type of royalty. We also see a great deal of plant life, yet it isn't the right type of plants. The ones that are left are the hardier river plants that are made to deal with the floods, and even then the black and the white add further dimension to the sickly state of the lands. The focal point of the picture - the man - simply looks ill and to me almost looks like Voldemort to an extent. However, the strangest portion of the picture is the very top, where we see a nautilus type creature attached to a man's head. Honestly, I'm not quite sure what to interpret this as, but I like to think the son is in the bottom portion fishing, while his father is enveloped by the grail keeping him alive.