Like a Bird This Story Flutters Around in My Chest (Worldbuilding Prose)

I have a story inside of me waiting to be written. This is a realization that is all-together exciting and terrifying, but mostly exciting. When I think about this story I am filled with joy, but this story comes out of me not in a torrent but as a leaky faucet. Here is a droplet from that faucet:

The throne room doors swung open just as King Antebar took his fifth leg of turkey. It was not customary for appeals to take place during the king’s dinner, but the man who was being escorted to bow before his ruler had bothered him so much lately that he wanted nothing more than to get rid of him.

“My lord your majesty,” began the man, who was dressed in monk’s robes several sizes too large for him. His face, a rather handsome one, was just visible beneath the shadow of the hood. “I thank you for taking the time to hear my pleas.”

The king, who was a fat, stupid man, grunted and waved a greasy bone at the peasant. “Just get on with it so I may continue my supper in peace.”

The man gave a curt nod as he rose from his prostate position at the king’s feet. “Your majesty, the people of my village have all fallen ill, but with what disease we know not. Our doctors have examined all of their books and have come up with no answer for the symptoms of our illness--”

“Is it fatal?” The king interrupted.

            “Well, no, not so far, but--”
            The king snorted. “Then it is not of any immediate concern to me.” He belched. “You are dismissed.”
            “No, sire, please!” The man protested. “You must help us! Simply issue a royal healer, that is all we require.”
            “I cannot spare any royal healers,” Antebar blared. “I need them all to be here in case I fall ill. The king is, after all, far more important than your little village.”
            The man in the robes grew red. “Your majesty, one healer is all I ask! A quick investigation and issue of a cure could not take more than a few--”
            He was interrupted by the king’s loud slurping as he sucked the marrow out of his turkey bone. Antebar was through paying attention. The man snapped. With surprising agility he leaped onto the king’s table, yanked up his sleeves, and thrust his hands into the king’s face. “Look at my hands!” the man screamed. He jerked back the hood from his face. “Look at my neck! You think this is not of any ‘immediate concern’? Just look at them!”
            Between the man’s abnormally elongated fingers stretched thin membranes like those of a fish tail, and the skin of his hands was scaly and tinted green. Carved into the sides of his neck were three pairs of gashes, which undulated as he breathed. The king shrank away from this freakish apparition in terror, holding his drumstick in front of him in defense.

            “Get away!” He shrieked, his voice high and shrill like that of a young girl. “Guards! Guards! Get this man away from me!”

            Two armor-plated guards closed in on either side of the peasant and unhesitatingly wrenched his arms back behind his back. As they dragged him flailing and red-faced through the doors of the throne room he cried, “You can’t send me away! You must help! Help us—”

            The doors swung shut and his voice could be heard no more. The king’s top advisor, who had observed the entire scene from behind a hidden window, moved swiftly to the king’s side to confer with him. “Majesty,” he said. “The man was from Coeur, at the source of the river. His is not the only case of strange happenings. Villages all along the river have reported sightings of strange beasts and unnatural crop failures even during times of plentiful rain. Something is happening, sire, and we must act fast before whatever it is reaches Sacrelle.”

            The king dropped his arms from his defensive position and sank into thought. “It must be spreading through the river,” he mused. It was an ingenious thought, which was, unfortunately, a rare occurrence for Antebar.

            The advisor snapped his fingers. “A brilliant observation, your majesty! And whatever it is must be coming from somewhere, so—“

            “We must build a wall,” said the king. He had a bad habit of interrupting people. “We must divide the kingdom at the river and stop the stuff from spreading.”

            “But sire, if we—“

            “It is the only way!” Antebar cried. “It is a sacrifice, yes, but if I must give up half of my kingdom in order to protect the other half from this terrible plague, I will do it. So to it that the building is started at once,” he told his advisor. “On the north side of the river. It must be impenetrable. I want it fifty feet tall and ten feet tall, and the seams between the stones must be smooth so it cannot be scaled. Demolish anything that stands in its way.”

            “But sire,” said the advisor. “What about the tributaries to the river from the north? The streams from Coeur must get to the sea somehow.”

            “Then build a canal for them along the wall, like a moat,” said the king. “To also discourage those who might wish to cross.” He abruptly turned addressed a guard, struck with a horrifying realization. “Quickly! The bridges must be cut! We cannot allow anyone from the mainland to infect the city! Go now!”

            The king’s original genius had quickly degraded to foolish desperation, but no one dared oppose him. The advisor and all the guards quickly cleared the room to attend to his commands.

            Within a year, the wall was built. The capital city of Sacrelle was cut off from the rest of the world, and the country soon fell into chaos. In that time any of those found in the south to be changed by the plague—it soon became known as the Plague of Wild Magic—were driven to the north or were killed. Centuries later, this would incite the War, which is where the story will begin.

 Here's the other drop in the bucket of this immense story stored up inside me.