Thousands of years ago. The world was inhabited by humans, just as we see right now. However, it was much different.

Evolved apes that were skinless and unable to survive in the cold, just as they discovered fire they were able to keep themselves warm. By then they needn't fur like other animals, they needn't claws to hunt, they needn't a great sense of smell to know where their prey was. All these factors helped them to gain a powerful mind, just to replace all the things they wouldn't need anymore.

Thus, with their creativity, they created. From houses, buildings, weapons, everything nature couldn't give them, or better said, they didn't want. Human's mind was a fearsome power, and they kept expanding onto the lands, modifying Earth just as he wanted.

But then, it didn't mean that humans were the only living creatures on Earth. From dogs to sharks to eagles to spiders, and among all of them, were the bacteria. Bacteria that, in order to survive, have to infect other creatures. This is what we call a disease.

However, no one ever knew of a disease that could control the human's mind, their thoughts, and their wills. Such a thing could not exist in nature, for every creature has its own brain and own mind, they take control of their actions.

But, just as thousands of years ago the humans were struggling with the cold harsh ice ages, were also the microscopic organisms. Most of them thawed after the cold ended, and most of those died and extinguished. However, who knows if there aren't any more frozen out there.

Out of nowhere, a young microbiologist, he might be, was inspecting the most frozen lands in the world. The team was experimenting, seeing how well microorganisms would survive in extreme temperatures, and they kept travelling all around the world.

The young man, who would be somewhere around his late twenty two years, decided to take a patch of ice or snow with him whenever he went. He said that he wanted to keep them and study how different were the snowflakes in different countries. His teammates were confused at first, but they knew that this man was, though brilliant, not very rational, and so they didn't pay much attention to it.

In one of their travels to Greenland, he saw on a glacier a patch of yellow. Not very noticeable at first glance, but since he was cutting some ice to take home he was able to look at it perfectly. It wasn't too big, but not extremely small either. So far it looked like a yellow worm, without too many features.

He was rather curious, but his team had so much work to do that he couldn't inspect it right away. Instead, he decided that he would take it home with him; after all, his teammates didn't care.

In a lone apartment he lived, away from most people. The place was calm, silent; perfect to read and study. His curiosity was big, for the first thing he examined was the frozen creature he found on the glacier.

He left it under the sunlight to thaw it, because doing otherwise could hurt the worm, and make him unable to examine it. He kept looking at it for hours, without even caring about food or sleep or exhaustion. He just wanted to know what kind of living being this was, since something frozen to him meant something ancient, a whole new discovery.

Hours went on, and a little part of the worm's head was thawed out. After more time, its whole head was thawed, but it wasn't moving.

So night came, and the ice was halfway there from being completely unfrozen. But there was no heat left, and using fire was too risky. He had hopes the creature might be alive, just as some creatures survive frozen solid. At the end he gave up, as he realized he had no ways to thaw the worm without harming it. He decided to wait for the next day and, as he woke up, he found it lying there, on his window, without making a single movement. It looked dead indeed.

He wouldn't give up anyway, for he had to know what kind of creature this one was. Was it from the ancient times, before man reached land, or was it an uninteresting recent worm that everyone knew of?

He began examining it with microscopes, mostly; taking out small parts of its tissue and examining it himself, since he didn't want anyone's help with his discovery. After all, those people had rejected him. Those people had fired him from his only job, abandoned him into nothing. This discovery would be his alone, and he would be recognized and respected by the world, by even the authorities.

While investigation obviously took some very long months, he was intelligent enough to overcome it. He kept the creature barely frozen inside his fridge, so bacteria and insects wouldn't ruin it. Then at an early hour he would leave it a few hours in the sunlight, and after that he would begin to work on it again.

There was a certain breaking point in his investigation. He was just staring at it, trying to remember whether this worm was some creature he already knew of or not. And then, he noticed, just barely, a slight movement of its head. While some people might believe it was their imagination, he kept telling himself that it wasn't, that the creature actually moved its head slightly to the right, that the creature was alive and it was not the wind or anything. So at the time, he tried stimulating it, so it would move again. It took him at least fifty attempts, for he already decided that he wouldn't give up.

Respect. Recognition.

At the last, he poked the creature from behind with a stick. With his frustration, he left a few marks on the creature, and even if he tried not to harm it, his anger made him injure the creature badly, to which it responded by instinct, trying to flee. At last, he thought, seeing the slow movements of the worm. Now, he would be able to study it as a life being.

Months went on. The creature had grown a little, but looked even less than a regular worm. On his studies, the young man managed to understand a little what this creature was. He bought a rat to make experiments, and he determined that this worm was harmless, but it fed on other creature's organisms. As soon as the rat died of old age, he opened it to see where exactly the worm was. His surprise began when he found it, small, still feeding on the rat's brain.

"So, little guy… you attack the most vital part of a living being…"

The worm on the rat's brain was one of the original worm's copies, or to understand it better, its offspring. He kept trying, with dying animals, infecting them with the worm. All with the same result: they didn't have any symptoms, but the worm was always feeding of their brains.

For a few days, he didn't want to do anything more but think. Think, about his discovery, the worm, the animals. His life, his job, his family. Everything that left him behind, everyone who laughed at him, everywhere he was not accepted. Everything the world's been through, everything the world survived. Everything humanity created, everything humanity destroyed; human's cruelty against other species, their cruelty against their own species, the sadness of living in this world.

A scream was heard. He was startled at the sound of his own raging voice, but it made him free. His thoughts were consuming him, and now he knew how wrong the world was. In his short life he never even saw real justice, but now Mother Nature has given him something.

Humanity has survived for too long causing pain. Now it's their time to pay.

He gave a quick glance to the Neurax Worm—as he called it—and remembered all the artifacts he had from his previous and only job. He was able to manipulate it. He could control it. He could make them fear the Neurax Worm, make it dangerous, make it lethal, make it kill; make it control human's mind.

Respect. Recognition. Fear.

He already had a way to control its evolution, but the Neurax couldn't be discovered just yet. Not with all the technology out there, threatening to kill it after it infected its first human. No, he needed something less noticeable. The rats and the other animals he tested didn't have any symptoms; they all died of old age or another disease. It was perfect to make it infect the world, before they can even know they've been infected.

That's all he had to do. No more cruelty on the world; the future was filled with sorrow. But now it can be like the first times, when the humans weren't fully evolved, when they weren't evolved at all. When they didn't need to kill each other, harm each other, and laugh at each other. A utopia, in which he would feel no pain anymore.

A Neurax Worm, undiscovered for thousands of years. Humans have entered its natural habitat, and given it the means to spread...

How long until the humans face extinction?

Author's notes: One of the few Plague Inc fanfics. I was inspired by the Neurax Worm's theme from Plague Inc.: Evolved. I'm planing to continue this until the end, and I hope you enjoy reading it as well.

(And sorry for the slow chapter, I can't make a story without telling the beginning, after all, can I?)

Anyway, I hope you enjoyed! Somewhere in the future I'll delete some uninteresting AN's.