When he was in fifth grade he had once forgotten a half-eaten lunch pack in his drawer. He couldn't really remember why he had put it there, but figured that it must have been because his mother always got angry when he didn't eat all his food. He probably had meant to empty it in secret, only to then forget about it.

When he had found it, it had made his stomach turn. The lid was transparent, so he could see the mold inside the box much too clearly. He knew average green mold but the kind he found there was a lot worse than anything he had ever seen before. It was almost pretty, like tiny black webs with tiny black heads that looked as if they could pop open any minute.

He threw the closed box away and always made sure that he didn't forget food afterwards. The mold somehow had left a deeper impression on him than anything he had seen in a dream.

So when he saw the black mold growing on Do Kyungsoo's left arm it made him feel sick.

"Oh, how lovely of you to come by," an eerily high-pitched voice said and Do Kyungsoo looked up, as if it was only then that he noticed the intruders. He was incredibly pale, as if all his life energy had been drained. Not even in his sleep he found any rest. "Are you friends? What are your names?"

"I'm Kai," Kai said and tried to surpress his anxiety. Nothing could hurt him if he followed the rules. He only had to hide his real name.
This time he would set things right. There wouldn't be any more mistakes, and afterwards he would maybe find a way to deal with the thing that had stolen Chanyeol's body.

"What the hell is this?" Chanyeol next to him asked in irritation. "What's that black stuff?"

Kai pressed his lips together. If only Chanyeol wasn't there, things would have been easier.

"I'm Kyungsoo," the high-pitched voice said. "And you are...?"

Chanyeol ignored it and angrily turned to Kai. "Is that a parasite inside my friend's mind?"

Do Kyungsoo took a step forward. The mold slowly spread over his chest.
The spores wouldn't be able to hurt them, not if they were prepared. The parasite couldn't do anything to Chanyeol, even if he was to blurt out his name, and Kai wasn't so stupid to allow anything to follow him back into his head.

"What's wrong with you?" Chanyeol asked. "Do you think the real me would hide in another parasite-infested dream?"

That wasn't the point.

Kai didn't want to be blamed for another mind that got lost because of a parasite.
Or so he tried to convince himself. In reality he just hoped to find a way to beat something that grew in a mind, slowly devouring its host. This was the only chance he had.

"What's your name, my friend?" the high-pitched voice asked, and Chanyeol scoffed.

"You don't know?" he asked in mocked indignation. "That really hurts my feelings, Fake Kyungsoo. I'm," Kai's heart seemed to skip a beat at the déjà vu, "Hong Gil-dong."

"Oh, I remember. My friend Hong Gil-dong!" the high-pitched voice giggled and spores burst from the tiny heads. Chanyeol shoved Kai away and pulled a face when he got covered in what looked like black snow.

---

"A parasite?" Kai had asked a few days ago when he had leaned his forehead against one of the windows of the corridor in front of his classroom. His mind had been racing.

"Well, that's what Chanyeol says," Baekhyun had shrugged. "Kyungsoo lately always nods off in class. I thought that he maybe just studies too much at night, but according to Chanyeol he probably has a parasite in his head."

It hadn't made sense.

With 'Chanyeol' Baekhyun always meant the impostor, that very impostor who had no reason to be helpful.

Kai hadn't known what to think. Maybe it was a trap the impostor had set up. Maybe he thought that he could get rid of Kai if he made him deal with another parasite. But he must have known that Kai wasn't a novice.
Why would the impostor give Kai any hints that could cause his own ruin?

"Chanyeol says that there's nothing he can do," Baekhyun had said. "But he told me that you're good at that kind of stuff." He had shown an apologetic expression. "I mean, I don't know how bad those parasites are, but, well, Kyungsoo is my friend and everything, so I want to help him. So, could you maybe have a look?"

It just had to be some kind of trap.

---

"Something about you is wrong," the high-pitched voice said and sounded strained, when Chanyeol wiped the spores off himself. The mold slowly covered the floor of the empty space they stood in. It had already eaten everything inside Do Kyungsoo's dream. There wasn't much left of the real him.

Chanyeol ruffled through his hair and shook himself in disgust, while muttering, "As if people from outside were so stupid to tell you their real names. 'Hong Gil-dong', my . I bet you're not even Korean, or else you'd immediately get that the name is fake."

It was odd. Kai wondered whether the Chanyeol in his mind was smarter because he was something Kai had come up with, or whether Chanyeol had just learned from his mistake.
They had argued about it a lot. "What can they do with my name?" Chanyeol had asked before. "It's just words."
He had only understood it when it was already too late.

"Something about you," the high-pitched voice slowly repeated and even more of the black heads burst, "is wrong."

Black snow covered the dream.

The scenery was different but the feeling was the same. A parasite devouring a mind.

Kai had been inside the head of someone whose soul had already disappeared. In the end there would be nothing but mold, black mold filling the empty dream like a tight web. Once it lost interest, the parasite would look for another host, forever wandering.

His grandfather had once told him that every parasite originally was a dreamwalker. Unable to face death, they had started to steal bodies, always losing a tiny bit of themselves. In the end there was nothing left of them but greed covered in a cocoon of death and darkness.

And it scared him, because, again, he found himself helpless.

Black mold crawled around him. "What's your real name, my friend?" it whispered and touched his shoe. "Don't you want to tell me? I can free you of all your worries."

Chanyeol grabbed his arm and pulled him away, meanwhile stepping in the mold.
"Look, Jongin," he said urgently. "This is really not the place to space out. We should leave, if you don't know how to fight this."

---

"Parasites?" his grandfather had asked sceptically. He was the last one Kai wanted to talk to about it, but he couldn't consult Chanyeol, who would obviously stop him. "Why would you ask? The best way to shield yourself is to hide your name."

"Yeah, but," Kai had said and had  tried to sound as if it was meant as a hypothetical question. "What if I accidentally tell them? Is there a way to get rid of a parasite?"

His grandfather had given him a long hard look, before he had sighed, "If you're so stupid to invite a parasite into your body, you deserve it. Unless it leaves out of its own will, you'll be stuck with it until there's nothing left of you."

"So you can't kill it?"

His grandfather had frowned. "I never heard of anyone killing a parasite. You'd have to be stronger than someone who was capable and ruthless enough to steal a body and eat its soul."

---

"We have to make it leave," Kai said firmly. "That's the only chance we have."

"Leave?" Chanyeol asked. "Where to? It's not like that would make a difference. It would just infest someone else."

Do Kyungsoo's complete left side was already covered in mold when he walked into their direction. His world was growing to be more and more grotesque. "Young dreamwalkers," the high-pitched voice said, and this time Do Kyungsoo's lips also moved. Both their voices formed a strange melody. "I will leave this boy, if you give me one of your bodies. I won't hurt you. We can have fun together." Do Kyungsoo face turned into a wide smile. "Much more fun than I and  this boy already have."

Kai took a step into the direction of what was left of Do Kyungsoo.

Maybe there was a way. No one knew dream spheres and their dangers as well as his grandfather, but his knowledge also set him limits. Because he knew the dangers, he was afraid to take risks.

Not even his grandfather could know whether it was possible for a dreamwalker to kill a parasite, because people like them knew how to steer away from any possible danger. Chanyeol's body got stolen because he had run, but if Kai just faced the creature head-on, he maybe had a chance.
He had to take the risk if he wanted to save Chanyeol. Even if he found him, they would just face the same dilemma again. Chanyeol couldn't just take his body, not if his impostor blocked his path. They needed a plan to fight it.

"Fine," Chanyeol said calmly. "I'll do it. My real name is Park Chanyeol, and you, Mr Parasite, seem like a really fun fellow."

What?
Kai's eyes widened in shock.

The high-pitched voice giggled. "My friend Chanyeol." The mold left Do Kyungsoo and formed something like a bizarre creature, like the hunched shadow of a person, that slowly slid towards Chanyeol. Do Kyungsoo fell on his knees.

"Are you crazy?" Kai gasped, and tried to drag Chanyeol away from it. "You're not even..." He wasn't even real. So what would happen to a parasite if it tried to enter an illusion?

The mold creature floated in front of them and held out what looked like an arm. "So what's your name?" Chanyeol asked and attempted to shake its hand, only to have his one get stuck inside. Mold started to spread over his arm.

"I'm Death."

Chanyeol snorted. "I bet your mother couldn't stand you." Mold crept over his body and grew into an even more bizarre web. The entire mold inside Do Kyungsoo's dream moved towards Chanyeol in strange waves. The black snow blocked their view.

Kai felt sick and turned away.
He just wanted to run, not just because he hated black mold, but because he couldn't stand the view. It was much too familiar. The view of a parasite stealing Chanyeol.

But this time something was strange about it. This time Chanyeol laughed.

"Well, you're really a sad little bastard," he said cheerfully when only his head was still free. "You call yourself 'Death'? I mean, honestly? Mold is not really a very dignified way to express yourself. How long have you been doing this now?"

A incomprehensible high-pitched noise came from his chest.

"Really? That's actually quite long," Chanyeol mused when mold crawled up his cheek.

The high pitched voice giggled again.

"You took advantage of a child, didn't you?" Chanyeol asked and touched his chest. "You were old and scared, and that child had a pure and simple mind, so you stole its body, didn't you? Zhong Zhaokang?"

The high-pitched voice screamed, as the mold suddenly turned into black cysts. Chanyeol's whole shape began to waver, as if he was made of boiling tar.

"Did you know, Jongin?" Chanyeol asked with a reassuring smile. "Zhong Zhaokang was a real ert when he was still himself. He didn't molest children, but he liked to walk into their dreams." The high-pitched voice made a gargling noise and Chanyeol's hand was thrown up to cover his mouth. Chanyeol slapped it down, and looked even more amused. "He tried it with women before, but back in the day everyone was a lot more aware of intruders in their dreams. One woman once beat him with a stick and he couldn't even fight back."

Chanyeol's chest burst. The mold tried to get away and back to Do Kyungsoo who stared at them impassively, but Chanyeol held it back.

"Did you know, Zhong Zhaokang, that fire can kill mold?" Chanyeol asked.

The high-pitched voice made terribly whimpering noises as it went up into flames.

It died.

The parasite died at the hands of a nightmare.

---

"Parasite?" the impostor asked and feigned ignorance. He didn't even slow down when Kai appeared next to him on his way to school. "What are you even talking about so early in the morning, my dear Kai?"

"I'm talking about Do Kyungsoo's parasite you supposedly couldn't do anything about," Kai said grimly.

The impostor furrowed his brows as if he had to think really hard to recall that memory. "Ah," he then said. "Yes, yes, sure, I remember. I wouldn't want to leave my new body, would I?" he smiled innocently. "But what about it? How did you find out?"
When Kai gave him a wearily annoyed look, he let out a short barking laugh.

"I see, I see," the impostor grinned. "You're not in a joking mood today, are you, my dearest Kai? Although I personally find you much too serious for a boy your age." He playfully patted his shoulder. "So what is it you want to ask? Are creatures like us all in a circle of friends? Is Park Chanyeol's head also full of mold now?"

"Why did you make me have a look at it?"

The impostor shook his head in indignation. "You're really straight-forward, aren't you?" he asked and let out a deep sigh. "Well, fine, let me tell you."
He stopped and gave Kai an amused look.
"I thought you might be interested to know what a mind looks like before something like us kills its soul. You've already seen the end product, haven't you? That's what this body's," he touched his chest, "mind also looks like right now. Because the soul got away."

Kai unwillingly looked at the place the impostor touched. Inside Chanyeol's body was a neverending inferno now.

"But at first it's the way Do Kyungsoo's mind looked like. I assume that it already was in quite an advanced stage. We enter the mind and quietly stick to the host, slowly draining all their energy. They don't even notice it at first. They walk around like ghosts and no matter how much they sleep, they never feel refreshed. Every day they grow a little more tired."

That's why even the people around Do Kyungsoo had noticed it, although they obviously couldn't find the connection.

"After a while they realize that they always see the same image in their sleep. In my case it would be fire, in Do Kyungsoo's it was mold. But there's nothing they can do, because it's already too late."

The impostor gave him an oddly sad look that made him uncomfortable.

"Did you know, my dear Kai? There are two ways to kill a parasite.

"The first one only works if you know its name. If you call it by its name, you can kill it the way you would kill a real person in the real world. But it's of course not easy to know the name of a parasite. Many of us have long forgotten theirs."

Kai frowned. Something was wrong.

"You see, the second way is similarly difficult," the impostor said and its lips curled into a thin smile.

"We can kill each other. Only a parasite can swallow one of its own, even without knowing its name beforehand. It can just enter the very basis of its kind and destroy it from inside."

So that was the impostor's real aim.

Without knowing his name, he couldn't hurt Kai the way he had hurt Chanyeol. But it was very well possible to plant tiny seeds of doubt and fear in his heart.