Luna stood atop the inner city walls. These walls were smaller than the outer walls, but it was a wall nonetheless. 

She looked toward the outer ring of the city, flames raging like wild pythons. Smoke billowed into the sky. Distant screams, coughing from smoke, the sound of a dying city echoing.

Screams of mothers, sons, fathers, and babies—young and old, they were all dying.

Luna's eyes were red with tears, everyone around her was dying yet she couldn't do anything to save them.

All these people were dying, but she was safe tucked behind a wall. She wasn't all-powerful, nor was she even a Grade 4; she was helpless.

All she could do was wait; to hell with everything else. All she wanted, all she needed, the only person worth anything to her. All she wanted was for that one person to be safe, everyone else could burn as long as he lived. 

"Cain…"

She was cowardly, she acted like a noble and compassionate person, but she was not. She was human, and all humans have a desire they will do anything to achieve.

…

Cain was sprinting as fast as he could. Jumping from roof to roof in the vast city. Ash was fluttering like silent snow, smearing Cain's face black as he ran along the wooden roofs with floating embers rising from below.

He lost his footing, falling through a weak charred part of a building. He was sent to the ground covered in soot.

But this didn't stop him, instead, he took to the streets. This took even more time than he wanted, as the streets were filled to the brim with the undead.

The more he ran, the less of the dead were walking the streets.

The army was paused, still eating inhabitants or maybe they just didn't care to invade more. This didn't matter to Cain. All he wanted to do was make it to the inner wall.

Even in the streets, he could see people fighting from time to time, the militia fighting with swords at hand, young men and even women fighting with mere brooms or pipes.

It was obvious that everyone was fighting to protect their family, for survival, and all Cain could do was wish them luck. He too had to protect his family and would do anything to do so.

Cain ran and ran, killing the few zombies left still in his way. 

With the streets becoming barren, Cain, with his enhanced body at full speed, only needed a few more minutes to make it to the inner walls. 

Of course, he also used some shortcuts thanks to his status as a plague doctor.

…

At long last, a man covered in blood and black walked up to a stone wall a few stories high. It was then he began to scream at the top of his lungs, trying to get the attention of those stationed on it.

"Hey! Down here! Let me in!"

There was no response for a long time. It was to be expected, they were under orders not to help anyone. 

'Screw this.'

Cain started to climb; no one stopped him. 

Reaching the top, he ran to the closest soldier and held him by the shoulders.

"Where is Commander Luna?"

The soldier answered, with Cain's crazed appearance he didn't plan to stop him. "Sir? Uh...she's near the inner gate with Lord Darius." 

'She's alive! She's alive!'

Cain high-tailed it to the direction Luna was in while also crying tears of joy knowing she was still alive.

Luna was discussing something with her master when she felt something odd. She turned, seeing a young man covered in soot, dirt, and blood. He was running to her with the biggest smile as if a 10-ton weight was lifted off his heart.

She seemed to become infected by the tears as they too began streaming down her face; they were tears of relief.

Luna immediately embraced the young man. Both crying while hugging one another. All the while Darius stood off to the side.

After about a minute or so, the couple regained composure and acknowledged Darius's existence. 

Cain turned to the man to ask a question amidst his damp face. Regaining his composure.

"How's the situation?"

Darius began to frown, reminded of the situation they were in. His dejected voice answered, "Not good. An elder was injured, and now they're holding a council inside the headquarters. It seems this outbreak is far worse than the last."

He paused before adding, "Cain... John died."

Cain stopped; his face turned into a blank look as if he was staring off into space. He couldn't even comprehend what Darius had just said.

'Master's…dead? A Grade 3 powerhouse? A borderline grade 4 plague doctor died? Impossible!'

Cain knew his master; even though he was known for his research, he was one of the most powerful people in all of Free City, a combatant with weapons that could be called biological terrors.

He couldn't process it all. All his brain could do was… pause.

From Luna and Darius's point of view, tears began to run down the masterless Cain's frozen face.

Although his master experimented on him and treated him like property, he was the only person Cain ever knew before meeting Luna.

He was like… like a father; he fed him, clothed him, taught him. He helped Cain become who he was. He might have been shady and had a lot of morals missing, but he was still his master, the person who laughed with him, studied with him, and grew with him.

Cain had long since grown attached to John. His mind replayed John's scholarly smile as he patted Cain's head while reading his first book.

Now such memories felt centuries away, ghosts of a dead era. Cain's ears rang as he struggled to stay upright, his legs numb weights beneath him.

All his moments now lived solely in his mind, preserved like insects in amber. Never again to be made anew.

John was Cain's father; although neither ever said it, it was a fact neither could nor would deny.

Registering what Darius said, Cain lost all his strength and fell to the floor.

He couldn't put strength in his legs; he couldn't put strength in anything. He let more tears run down his face as he started to cry while he held his fists to his eyes to rub away the tears.

…

Luna once again checked up on Cain; his eyes were still red, his face pale and weak. 

"Cain…you know I'm here for you. Now and forever, so take as long as you need."

Cain was still unresponsive and only reacted when Luna hugged him, in which he would hug back.

It had happened, he was back in that dark, damp alley.

Once again Cain had lost something precious to him. Before, he lost his childhood and sanity, being left with a hollow shell that never recovered. 

Of course, he didn't fall to a point of madness and delirium, he still had one last rope to hold onto before he fell into the abyss of insanity: Luna.

He still had the one person left in his life, the most important person he must protect.

…

At some point, Cain got himself together. He went to find Luna and Darius, who both had looks of worry, both for different reasons. 

Cain got all the information on what happened, on John's death.

The biggest reason John died, was unlike the other outbreak 500 years ago, this one was organized; they had a leader.

They didn't know this Leader Undead's strength, but it was on the level of Grade 4. John couldn't hold it back. He died while protecting the retreat and sacrificing himself by blocking the leader from advancing.

It seemed like the story of a hero. Right?

Cain couldn't understand why John would do it, but then he realized that John was with Darius and Luna. The reason he would do something so selfless, was to perhaps protect Luna? 

'It's the only possible conclusion.'

Cain tightened the grip of his fists as his nails dug into his flesh. He was useless; he wasn't even awake during the first attack!

He failed himself, he failed Luna …and he failed John.

All he could do was burn the image of the undead leader into his mind. As Darius described it, it was a pure white-skinned human. It didn't have any features of being undead except for its arms and legs, which showed protruding bones, it did not have any genitalia.

"Remember Cain, do not fight it. It's been showing intelligence by leading and organizing the dead. Even now, it's building up its forces."

The red bags under Cain's eyes were still visible. "Fine…but at least give me a position where I'll be able to get a few hits in."

Darius thought for a moment. "Well… we have a watchtower still equipped with some ballistas. You and Luna can camp out there, there's a chance you can hit the leader if he comes this way"

"That's all I ask for." A hidden madness sprouted in Cain's mind, it grew at a rapid pace.

…

The reason why the zombies couldn't break the walls and had to climb them was that the walls were made up of the ancient stone that Cain had seen used in rituals. It was also what was around the vault.

From what he could tell, it was strong. Some runesmiths even used it in a type of runic magic; it was the cornerstone of the Union and Free City.

Cain and Luna were already situated in the stone tower. Both of them were stationed on the crossbow constructs

The ballistas were at least the size of Cain and then some. Large arrows were racked in the drawstring, they had dark metallic tips that seemed almost magical...almost.

Cain and Luna aimed them towards the area in front of the gate and waited.

In preparation for the fight, they would calm their nerves, by playing cards. It was just old times. Such times were in the past now, they could only feel a hollow sadness while they played.

They had each other, but they couldn't take solace in it, not in this situation where death could happen at any time and so many had died. All that mattered was the other one was alive, but that was the limit of joy they could feel.

Just a few days ago, they were having dinner spending their days in bliss.

But now it was hell; things had happened that could never be forgotten, and even if they survived, that bliss could never come again.

These monsters had taken his life from him. Cain could never live the same with Luna. He lost something he could never get back.

It couldn't be stopped anymore, all of Cain's hatred was beginning to boil, and his veins began to burst at the thought of this 'Leader of Undead'.

It was then he decided to do anything to take his revenge; his rage overflowing and pouring out of him. For the one who took his life away, a life that he could never get back, was none other than that monster, for he was the source!

However, the source was something much different, such a source was one no one could guess.