This is written for the Hogwarts Witchcraft and Wizardry (Challenges and Assignments) forum, specifically for Assignment #4; Survival Skills: Water - Task #9: Write about a thirst for something (knowledge, literal water, go wild).

For the majority of this piece, I say hungry/hunger rather than thirsty since its fits better - but they are synonyms, so I would say it works. Not gonna lie, I saw this prompt and my mind instantly went to the idea of Dementors and hungry. It was much harder than I expected it to be, which is also why it's so short (around 460 words by the end). I did, accidentally, do some world building wherein the Dementors have a hive-mind and a new Dementor is formed when a soul is taken. The ward-line is probably a spell that gives the "borders" of something to the Dementors so they know the boundaries to guard. There are probably orders of some kind that they are bound to or something. Anyway, enjoy!

It was hungry. Hungry, hungry, hungry. All that existed was hunger. An empty chasm that formed its existence. It craved sustenance. It had come here with the rest of its swarm, asked to follow the ward-line and ensure SIRIUS BLACK, (grief-anger-guilt), did not cross the ward-line, and hunt SIRIUS BLACK, (grief-anger-guilt), if ever he came near.

(Take his soul. Be sated. Grow in strength.)

There was prey here. Off limits. Off the ward-line. And it was hungry. So, so hungry. So was its swarm. The hunger ate any thought, swallowed anything one of them consumed; all of which was shared around. It wasn't enough. Not for the whole swarm.

They had kept to the ward-line and starved for months. Followed the orders they were bound to and allowed suggestions that they don't attack any prey to keep them at bay. But no longer. Keeping away from the prey was not an order they were bound to.

It felt the rise of the swarm in its mind. They were all so hungry. They were naught but black pits. It was an awful existence. In the distance, a blur of light and sound and magic and happiness clashed against the dreary surroundings. It was a feast and they had all been hungry for so long.

Without another thought, it flew towards the excitement-happiness-go!-go!-go! and away from the ward-line. It called the swarm to it. Now, they would no longer be hungry. Now, they would feast. Now, they would be sated.

The swarm collided, abysses and pits merging together. All they were was hunger and then-

Then the abyss started filling. The excitement and glee and happiness swallowed and sucked down without a thought. Instinct. The swarm swirled through the clouds, nimbly closing in on the happiness-glee-go!-go!-go! in the air, (they were creatures of the air, and better for it, these prey of the land would not outrun them). Soon, they would grow in number. Soon, they would be sated, (for a little while—only ever for a little while). Soon, they would not be hungry.

It glided down; the swarm branching out around it to swoop and claim meals of their own. Except-

Screeching, it recoiled. The magic in front of it grew and swelled; silver light forming a shape of some sort. The happiness-happiness-happiness was too strong and too dangerous. It screamed again and called the swarm together. They would not be defeated here. But the happiness-happiness-happiness grew bigger, grew stronger, and they were so weak, (so hungry).

The swarm was defeated, chased back to the ward line. Angry and ravenous, it screeched and screamed and swooped over the ward-line, again and again. But there was no prey to be found here. It would continue to be hungry.

The swarm was always hungry.