In the town of Yoen, five years had passed.

Cain was 18 years old; he'd had grown during his time living in the trading town.

Even so, Cain lost much of his memory of the event five years ago. Perhaps it was a coping mechanism from the trauma, but he had no recollection of what occurred.

The memory was forgotten and locked away. But that terrible event still had an effect, whether the attack or the serum.

Cain found it hard to crack a smile. The youth brushed off John's jokes and kept to himself, often disappearing for hours alone. His eyes grew stormy, and his voice flat.

John took him in when Cain awoke from the operation five years ago. Over time Cain got used to living with him but would ask about Feick's whereabouts.

John, of course, told him Feick left town with a convincing reason and explanation.

But Cain had a gut feeling; his mind stopped believing what it was told, not even for a second. John's honeyed words caused him to grow suspicious.

Once he got settled as John's apprentice with fake documents and the like, Cain would investigate.

It didn't take long to gather enough evidence to find John's claims false, which led him to the conclusion that John killed Feick. But, he couldn't care less, Feick couldn't be trusted any more than John. He may have helped Cain but after learning more about contaminants he doubted the old man's reasons for saving him were out of kindness.

He didn't know why John killed him, but over the last five years, he had mostly forgotten about it.

The thing that made him uncomfortable the most was the way John treated him. He would refer to Cain more as an object than a person, never hiding his obsession. Yet these weren't the focal points of Cain's life. No, it was what John's serum did to him, as it changed him more than he could ever know.

After the operation, when he woke up. John found Cain's strength equal to a grown man, as a child!

His body's overall fitness peaked and broke through a few additional boundaries. Of course, this is normal for those who augment themselves with viruses and pathogens.

Yet John found Cain's pathogen-reinforced body to be subpar. His body was no "Divine Body" for augmenters; it was even of a lower grade. Of course, John's research was not that shallow.

If you were to imagine a normal augmented body as a hard concrete block, Cain's was a hollowed-out concrete block.

This hollow brick was incomplete, to finish it, one needed to fill it. This would be by adding specific diseases and viruses, adding them to the foundation, filling the hole, and therefore becoming stronger.

This development wasn't bad, quite the opposite. This meant Cain's physique could grow, something that went against the current norm.

This gift was a great boon, but it also had limitations, once Cain added something to the formula, he would not be able to take it out.

Nonetheless, this discovery made John happy to an extreme; if improved right, Cain could become unfathomable in physical strength; none would be his opponent!

To achieve such an outcome would require research. John couldn't focus on researching alone, being stuck in Yoen, many premium materials for such a project, even in all of Netherane, would be extremely rare.

If Cain wanted such a body, he would have to spend years finding and researching different things to integrate into his body.

This was still a positive! Cain now had the chance to become one of the strongest alive!

Through the five years staying in Yoen, Cain also studied under John and became a successful plague doctor; he was not on John's level, but he was far better than others his age.

From John, Cain learned that there is a ranking system for plague doctors from 1-5. Below Grade 1 were apprentices, and it took a decade to become Grade 1 without talent in the field.

Stolen novel; please report.

John was at the barrier between Grades 3 and 4, while Cain recently became Grade 2, revealing he had a rare talent for diseases.

In simple terms, the grades advanced with the Plague Doctor's understanding and control, allowing for more diseases and pathogens as they advanced.

Once a Plague Doctor reached Grade 2, they would have some combat power, and Grade 3 would be where they were among the best.

Grade 4 was the peak, as the mythical Grade 5 was only rumored and even the great Grade 4's have never had a hint of entering such a realm.

Then there were classes like Augmenters, those who had undergone body modification. They are unable to improve or advance in rank. The serum they first take is the serum they're stuck with for life. All Serums have Ranks, similar to Plague Doctor Grades.

Because of the current understanding of augments, it was easy to see Cain achieved something never done in history.

However, John noted augmenters were a branch of Plague Doctors.

The case is that augmenting helps strengthen the body and shouldn't be a focus. It's an additive to the strength gained through knowledge.

To advance as a plague doctor, one has to "understand" a disease. This is done through studying them and researching them to a point where the Plague Doctor should be able to explain everything about the disease over dinner, its target, how it travels and infects, the time it takes to infect, what it is made up of, etc.

It's like an obsession. This is also why John views Cain as an object. He is his research, his understanding.

For Plague Doctors, reaching the lower Grades is easy as there are libraries that have centuries of information one can read from even if they don't have talent.

When one understands a pathogen, one can gain a sort of connection to it, which allows magical control over it. When you understand the rules the bacteria follow, you can control its path.

John even showed Cain what a Plague Doctor's power looked like.

During one of their experiments, he gestured to a patch of mold growing in a petri dish. Cain watched as the fuzzy green mold began to move, forming a miniature tower at John's command.

When Cain later tried to simulate what John did, he found it difficult. Even if he had a good understanding of the bacteria, it was like controlling another limb. A limb that was dead. In a sense, he was trying to use his understanding to force the bacteria to act out his will, manipulating it.

But one person's understanding can trump another, this was why Plague Doctors find and cultivate personal diseases for battle.

To be more accurate, understanding a pathogen was like a skill. This was why the diseases someone studied were important for later development.

But one to advance from Grade 2 to 3 required understanding exotic and rare diseases. At this point, no amount of common knowledge could help. Such diseases were kept to the plague doctor who studied them.

To pass on this knowledge, powerful masters took in students to teach. In a sense, it is like handing down a secret technique. This practice was a tradition that allowed knowledge to be updated continuously.

If anyone ever needed to be cured of these rare diseases, the Plague Doctor could make a trip. It may be slow, but Plague Doctors wouldn't simply give away their secrets for nothing.

The system gave Plague Doctors power while keeping the majority of the populace safe from disease.

But this was not all Cain was told.

"Remember, even if this way is good, it still has drawbacks. New diseases can always pop up without anyone to study them. Which is why I don't want you studying my diseases."

Learning about new diseases was an issue. It was way harder starting from scratch.

It got to the point where people began to search old structures and ruins to find decades-old notes for some half-extinct bacteria related to a current one. New diseases would emerge while old ones mutate, making prior knowledge obsolete. To be a Plague Doctor was to fight against Nature itself.

Under the current Plague Doctor system, even with so much knowledge, peoples' health will deteriorate until even minor illnesses become lethal.

There are examples of this. Five hundred years ago there was an outbreak of a pathogen that turned people into what is called a zombie but since it was a bacteria it wasn't too dangerous in the beginning.

It spread all over Netherane and caused humanity to almost collapse. But a cure was made, saving the remaining population and allowing humans to push the bacteria to near extinction.

This disease, Zimostafacus, also known as the Zimo disease, became prevalent again. Yet none of that was important. What was important was not a thing, but a person.

Cain was talented beyond belief, having long improved himself and become quite a good doctor; his favorite diseases, which are the ones he is focusing on currently, was Trachoma, a bacteria whose only symptom is loss of vision and blindness. There was also Osteomyelitis, a disease that weakened and damaged the bones.

The bacteria are in the ranges of common but Cain wanted them for their effects. He hoped to use them in combat.

Plague Doctors didn't just use pathogens to attack. Some diseases were used to heal, defend, or even control others.

...

Cain grinned as he gazed out at the decaying town. After five years in this cesspool, he had adapted. The once small boy had become ambitious, reading every book in the local library, and John's private collection to boot.

In light of his students' rapid progress, John decided to return to a Free City to acquire better resources. He also wanted to find bacteria or viruses that fit Cain and his physique.

After packing all day with John for their trip to Free City, Cain looked behind them as they left.

Memories began to flood his mind. He had spent most of the last five years here alone - studying in the clinic, running errands, researching at the library.

Now, leaving, a smirk erupted across his face as he turned back and sat in his seat.

'Hah....I hope life will become interesting from here on out. I've been cooped up in a lab all my life so far.'

He was excited about what the future would bring.