Title: Nature vs Nurture

Fandom: Yellow

Timeline: After Mizuki and Katsuro have escaped at the end of Volume 4.

Summary: Just what impact do we have on the lives of those around us?

Disclaimer: I do not own the characters in this, they belong to the creator of 'Yellow'.

"How did things go so wrong?" Mizuki gazed morosely out the window of the speeding train.

"What do you mean?" Katsuro asked, not looking up from the sports magazine he was flicking through.

"With Taki. Where did we go wrong?" Mizuki tapped long fingernails absently against the glass as the darkness flashed by, broken infrequently by the winking lights of towns passed.

'Hmm?" was Katsuro's absentminded answer.

"It was a mistake," she said suddenly. "We should never have taken him in."

Now Katsuro did look up, gazing at his partner sitting opposite. "Are you saying that you should have put a bullet through his brain right at that moment we first met?" he asked forthrightly, thinking to shock her

"Yes!" Mizuki said quite firmly as though she had no doubts but Katsuro noticed her finger-tapping became a little more agitated.

"Yeah, right," he murmured mockingly. "There was no way you could have done that. Not after he had come directly up to you and took your hand the way he did. Don't talk nonsense."

Mizuki turned her head away from the window to look at her partner, frowning at him. "I'm not. We should have just walked away then. We were foolish to take in a kid."

Katsuro shrugged, turning a page. "It's a moot point now." he stated, still looking relaxed.

"We were too soft on him." Mizuki continued, returning her gaze to the dark window. "We should have been stricter."

Katsuro sighed and laid the magazine down on his knees, realizing that he was going to get no peace to read. "So, what? We should have made him like us? You know 'Sandfish' only works as a pair. There was no room for a third."

"I know. That's what I mean. We made a mistake in taking Taki in. He was too nice."

"Too nice?" Katsuro didn't understand why Mizuki seemed so hung up on this. Sure it had been a shock to her to realize that no matter what she did the object of her obsessive love, Taki, would never reciprocate those feelings but he had thought she would have reconciled herself to that quickly enough once it had truly been brought home to her.

"Yes!" she answered his question. "He was too good all the time. He had too kind a heart. He's just too…good!"

Mizuki spoke passionately although her hands were clenched tightly in her lap. She leant her head against the glass, feeling the coolness against her skin. "He was too good for us. He would never have fitted in."

"You still don't get it, do you?" Katsuro said after a moment's silence.

"Huh?" Mizuki looked back at him.

He gazed at her steadily and shook his head sardonically. "Sometimes, Mizuki, you are so dense."

"Why?" She bristled at the criticism.

Katsuro stretched his long legs, leaning back in the seat more comfortably. "Because you haven't figured it out even now."

"Figured what out? What are you talking about?"

Katsuro smiled crookedly. "We are responsible for how Taki is," he said calmly. "You and I."

Mizuki stared back at him in shock. "What are you saying? Don't be stupid! We had nothing to do with it!"

"You can try and deny it all you want, Mizuki, but it's the truth. From the moment we took Taki in we have been responsible for moulding him into the man he is today. So we only have ourselves to blame."

"That is not true!" she snapped.

"Of course it is," Katsuro replied unperturbed. "Sure he was a good kid right from the moment we found him. He had a very trusting nature back then otherwise why would he have come up to us so readily. But that doesn't mean much."

"You don't know what you're saying!" Mizuki flicked her hair over her shoulder in an angry gesture which made Katsuro smile in amusement. She really was just so much of a woman now. He could almost completely forget that she had ever been a man at one time.

"Who was it who read him bed time stories at night?" he continued calmly. "Who was it who made certain that he never saw a gun, a shell, smelt gunpowder on clothes or saw blood on anything when we returned from a job? Who was it who taught him right from wrong?" His partner said nothing. "Mizuki, we were his parents, we raised him. He turned out exactly the way he is because of what we taught him."

"We didn't teach him to turn on his parents!" she snarled.

"No," Katsuro agreed. "But then he didn't really turn on us."

"What?!" Mizuki's head spun round, eyes wide in disbelief at what she was hearing. "How can you say that?! After what you have just seen tonight!"

"Choosing someone else over us isn't the same as turning on us." Katurso explained. "He didn't turn us in at any time. He kept our secret all these years, even after learning what we were and what we did. Even when we sent him the calling card this time he never turned us in. He's had plenty of opportunities to do so from the time he was old enough to do so."

"That's only because he was scared he would be held accountable as well because he thought he had killed that girl!" Mizuki said with a disdainful sniff.

"You think that was all it was?" Katsuro asked. "I doubt it. It would be hard for anyone to have proved he had anything to do with it. Would the authorities really have believed that a kid like him would have done that when 'Sandfish' was right there and had already killed the mother? Course not! They would be only too quick to blame us for that and would hardly believe us if we tried to deny it." He looked at Mizuki with a crooked smile. "We would hardly be considered the most trustworthy of witnesses!"

Mizuki's eyes slid sideways, refusing to look at her partner.

Katsuro continued speaking. "No, it would have been very easy for Taki to betray us at any time and he would have been quite safe in doing so. The main reason he didn't do it was because we are still his parents in his eyes." He gave a low chuckle. "He really is an idiot son sometimes!"

"You're just trying to make excuses for him!" Mizuki said sharply.

"Oh?" Katsuro raised one eyebrow. "Isn't that your department?"

She glared at him but he just shrugged the look aside. "You were always the one to coddle him the most. Right up till the end you kept trying to make excuses for his behaviour."

"And look where it got me!" she snapped back.

"What? Dumped?"

"No!" she said sharply. "He betrayed us!"

"Don't be foolish. Right up to the end he was just trying to make us change." Katsuro sighed softly. "He still doesn't get it that we can't. We are what we are. Just as he is what he is. You can't change that. But he was still trying to. He still wanted us to. Poor kid."

Katsuro now turned his steady gaze to the night outside. "Deep in his heart I think he was still trying to return to the time we all shared before he found out what we were." He snorted softly. "He really is an idealistic fool."

"We should have changed that."

"What? Made him a killer?"

"We could have." Mizuki defended.

"Sure we could have. From the time we found him we could have placed a gun in his hand and taught him to shoot. Started him off killing cats, dogs, birds, what ever else there was. We could have taken him on our jobs and let him stand in the blood pooling around the bodies we left behind to desensitize him to it. Starting him at that young age it wouldn't have taken long before he would have seen nothing wrong with killing, not to mention he would have been a damn good shot before he had reached his teens. But we didn't."

Mizuki opened her mouth to say something but he cut her off.

"What did we read him?' he asked her. "His favourite stories were Aesop's fables. He used to love it when you read those to him. I remember him begging you to read them over and over."

"You were no better," Mizuki challenged. "What about Rudyard Kipling, or Grimm's fairytales, and so many of the old Western classics? Just because you liked them you foisted them on him also."

Katsuro acknowledged the accusation with a half shrug. "Guilty as charged," he said calmly. "But that's what I mean. We brought him up on stories of courage, of doing the right thing, of learning to think for yourself, of wonderful and mystical lands and creatures." He grinned. "We brought him up believing in the good of the world. We made absolute certain that he only got the best of everything, experienced the best the world had to offer and never let anything touch him that would soil that view. How can you be surprised now that he actually lived up to all that? He has only fulfilled our every expectation as our son, based on what we taught him. No matter how you try and look at it, Mizuki, we are responsible for the person Taki is today. And he will continue to grow and learn from others now also. His partner will see to that."

He saw Mizuki grind her teeth. "Then if we are to blame we should have done it differently. We should have replaced him and taken in the girl!"

"Now you are just talking rot!" Katsuro snapped, his voice hard enough to make Mizuki flinch and her face flushed with embarrassment. "Even if you could have brought yourself to kill Taki that night do you think we would have done anything different? Course not. We would have done exactly the same thing and Mari would have turned out no different to what Taki did. Except you wouldn't have hit on her!"

"Don't. Please." Mizuki dropped her head so her long hair hid her face.

Katsuro stared at her for a moment and then closed his eyes with a small sigh. "I'm sorry," he said quietly. "That was cruel of me. Sorry."

"It's all right." Mizuki said, reaching up a hand to wipe delicately at her face and he could see the slight gleam of moisture for a moment on her cheek and felt a little guilty. His aim hadn't been to hurt his partner. He forgot that she could be so sensitive at times, and that was something that hadn't changed just because she was now a woman. Even before, she had been prone to it.

Mizuki had always felt everything with a passion, when she finally did feel something. When it came to the job she was as cool and calm as he could want in any partner but when she truly wanted something, when she truly found something to touch her and rouse her passions she felt it with such intensity it was almost frightening. As Taki had found out.

The trouble was, that when Mizuki felt passionately about something she was always in danger of destroying it from her own desires. She hadn't learnt yet how to temper those feelings. He was sure that she could, with time, it was just that they were still so unusual, so strange for her. Having Taki run away as he had hadn't given her time to actually get her feelings for him into perspective which probably would have helped her develop a more balanced view of them. He knew he couldn't tell her any of that at that time though. It was just something that she had had to learn. He hoped she understood things a little better.

Now, he gazed fondly at his very feminine partner, now he felt that he could teach her about those types of feelings, not that he was really any expert. He silently laughed at himself. They really were suited to each other – both as emotionally damaged and unstable as the other, just in different ways. But who else would be able to understand them except each other?

No, he had no intentions of leaving Mizuki. He had no desire to have any other partner except her. Not until one of them died, or more likely they put a bullet in each other. Now that he could definitely picture. So how sick did that make him that such a thought actually pleased him?

He mentally shrugged. Ah well. That's just them.

"So you really don't think we could have done things any differently?" Mizuki broke the silence again, fingers back to tapping on the window pane.

"No, I don't believe so."

"Do you think Taki will ever forgive us for what we did to him? What we forced him to choose to do?"

"He already has."

"You really think that is the truth?"

"Would he still call us his parents if he hadn't?"

"I guess not." There was silence again. "Perhaps we should have told him."

"About what?"

"About how he came to be with us."

"You don't think he'd already figured that out?"

Mizuki glanced at him quickly. "What makes you think that?"

Katsuro smiled grimly at her. "He knew what we were that night on the cliff. Do you think after we told him we couldn't have two children and that he could be replaced by that girl that he wouldn't finally put two and two together?"

"Then that night, the night he ran away..." Mizuki's voice faded away.

"I don't think he realized right at that moment. I don't think he would have figured it all out until he was a bit older and a bit more mature."

"So you think he knows that we killed his parents?"

"Taki's not stupid, we didn't raise him to be. He's smart enough to put the pieces in place and work it out. After all, why would two assassins take in just any stray kid they came across? It doesn't really fit the profile, does it?"

"But if he knew, why…"

"Why does he still care about us?" Katsuro finished her sentence.

"Yes," Mizuki almost whispered.

Katsuro gave a low laugh. "Because it comes right back to what I was saying at the start. I doubt he had any memories of his parents; he was rather young back then. We were everything to him. We cared for him, we fed him, we kept him safe. We laughed with him, we scolded him, we taught him about life. We showered him all the love we could." He looked at his partner with a smile. "What kid wouldn't love parents like that?"

"But how could he still think that way after realising we must have been responsible for his real parents' deaths?"

Katsuro shrugged. "Perhaps those 'parents' are like nothing more than a vague dream to him. He doesn't have any emotional attachment to them because they didn't have enough time to become 'real' to him. To Taki, we are and always will be his parents. Besides," he smirked. "He still loves us even though he does know we are killers, even after seeing us kill and even after we forced him to kill also. Isn't that truly love?"

"I wish we hadn't done that." Mizuki said in a low voice. "That really was cruel."

"You've changed your tune." Katsuro expected Mizuki to snap back a sharp reply but there was nothing.

"Perhaps. But he was our son and I really did love him, in all ways. I really didn't want anything bad to happen to him. I truly did want him to just be happy."

"Just like a mother." Katsuro said with a smile.

"Is that wrong?" Mizuki said sharply.

"No, not at all." Katsuro stated, shaking his head.

"What about you? What did you want for Taki?"

"Me? I guess I wanted him to be strong. I must admit that when he found us that night and tried to defend that girl, defying death itself I was pretty damn proud of him. I remember thinking, that's my boy!"

Mizuki looked surprised.

"What?" Katsuro said with amusement. "Can't a dad be proud of his son every so often?"

"So you really didn't want to replace him either."

"Not for one minute. But we couldn't have two kids with us; one was enough of a liability although I have to admit that it did give us a good cover at times. But that aside, no, I didn't want to kill Taki that night. But the only way for that to have been resolved was in exactly the way that it was. It was up to him to choose to live, with us, and with the knowledge of what we were. There was no other way."

The silence stretched between them again.

"That was a crap job." Mizuki finally said. "Our client never gave us any information that there was also a child."

Katsuro stretched his legs again, realizing that Mizuki was once again referring to Taki's parents. "Yeah. Well, you know how poor the intel can be sometimes on the jobs. That's why it's better if we do the research instead of relying on others."

"Hmm. Well, we haven't made that mistake again, have we?"

"No. We've obviously learnt our lesson."

Katsuro reached out and picked up the magazine again. He flicked past a couple of pages then looked at his watch. "Try and get some sleep," he said, closing the magazine once more and reclining the seat. "We've got time."

Mizuki also reclined her seat, although she curled up more against the side of the train, drawing her bare feet up onto the seat under her.

She looks like a little kid, Katsuro thought with amusement. "Want me to tell you a bed time story?" he said with humour.

She frowned at him. "Your stories would probably give me nightmares!" she replied, wriggling to get more comfortable and giving a little sigh when she was.

Katsuro closed his eyes but opened them again when Mizuki spoke quietly. "Do you really think Taki will be all right now?"

He met her clear gaze and smiled warmly. "I think he'll do just fine," he assured her. "He's got someone who loves him by his side. How can he not be okay?"

"Someone who loves him," she murmured sadly. "Yes, that he has."

"Feeling lonely?" Katsuro asked her.

"A little," she admitted in a small voice.

"You don't have to be," he said. "I'll always be here."

They gazed silently at each other and then Mizuki smiled. Katsuro had always liked her smile.

"Yes. So you are. And I'll always be by your side."

Katsuro closed his eyes and settled back further in his seat. "Then neither of us needs to feel lonely, do we?"

"No. Not at all." was Mizuki's quiet answer.

Tomorrow was another day. Another day of living, another day of working, another day of running, another day of hiding. They never knew what each day would bring them but they did know that whatever it was they would be facing it together.

'Sandfish' would still go on.