"Homonculove" by Mereo Flere

A/N: A Prismatic Illya based scenario, where it will mostly focus on how Shirou became accustomed to being part of the Emiya-Einzbern family.

Prepare for just an ordinary slice of life story about a cute family doing cute things.

…well, maybe they're not that ordinary.

XXX

The sun was shining that day, like a bright smile that congratulated the boy on his discharge from the hospital. Its light was warm and comforting, and to Shirou it seemed to promise that peaceful days were waiting for him. However, that thought does nothing to reassure him at all – instead, it only puts him at more unease.

Is this really okay? That was the thought that goes through the boy's mind, as he looked up at the man beside him – the same man that had saved him from the fire, and visited him every day while he was being treated. That was already more than enough compassion shown to the boy – but to go even further, for the man to invite Shirou into his family… wasn't that just a little too much?

The man, Kiritsugu, looked down at the boy and gave him a smile as bright as the sun's rays. He saw in Shirou's eyes the worries going through the young boy's heart, and answered the Shirou's unspoken question with a gentle pat on the head. Kiritsugu then turned his eyes forward – to the house that he and his wife had purchased together. It was where his family, Shirou's family, would live together from now on. "Welcome home," he said warmly, before he gave Shirou a gentle push forward.

Shirou, though still afraid of doing something wrong, had no choice but to take the first step toward the future.

XXX

As a maid, Sella was used to going along with her mistress' whims. Irisviel, after all, could be a flighty person at times. Though her mistress was responsible in the times she needed to be, Sella had no doubt that the number of times Irisviel had brought strange things home is greater than the stars in the sky.

However, that was Irisviel. It was only the mistress that brought back weird souvenirs like a snakeskin fossil, a coin supposedly possessed by a dragon, or that one pile bunker that seemed to cause all of the carrots in the refrigerator to disappear. Her husband, Kiritsugu, usually had much better when it came to bringing back gifts.

…usually.

"And so that's why Shirou will be living with us starting today," the man explained – cheerfully grinning at the maid as the boy bowed politely when he is introduced.

"I-it's a pleasure to meet you."

If not for her pride as a maid she would have palmed her face in exasperation. Instead, she simply sighed and shook her head in wonderment.

"Kiritsugu-sama," she said in a weary, almost impatient tone. "Have you even discussed this over with Irisviel-sama?"

"Of course," Kiritsugu said with a nod. "In fact, it was her idea. She said a big brother would be the perfect present for Ilya," he continued, confirming the maid's suspicions of Irisviel sapping away his common sense. Still…

Sella massaged her temples, trying to delay the oncoming headache. Even if Irisviel was an easy going person, she wouldn't have made such a life altering decision on such a whim, right? Of course not, Sella assured herself... though that didn't change the fact that that sounded like something Irisviel would say, whatever Sella's mistress' true intentions were.

"Yes," Sella said, as she removed her hand from her face. "That sounds exactly like something she would say."

Even if she was troubled by the way her masters decided things, it wasn't her role to question Irisviel and Kiritsugu. No – more than anything else Sella had a duty to support her masters, no matter what path they decide to tread. Thus, despite the reluctance that took hold of her heart, she ignored those feelings and held the skirt of her uniform outward, curtseying for the boy.

"Welcome home, Shirou-sama," she said stiffly – careful to remember the suffix.

Shirou wondered, once again, if this would really be alright.

XXX

Where Sella had shown a disinclination to accept Shirou, the other maid of the house, Leysritt, had greeted him with a hug almost immediately – picking up the boy and smothering him with her ample chest. It was a gesture that was infinitely friendlier and more dangerous than the other maid's had been – for a moment Shirou had been sure he would suffocate, had Sella not stepped in and pulled them apart.

"He isn't here to be another maid," Sella explained dryly, able to understand the strange train of thought that had gone through Leysritt's head.

"Of course not," Leysritt said, blinking. "Maids are women. This is clearly a boy," she continued, turning Shirou around to face Sella. "Here, I'll show you."

Instinctively, Sella pulled Shirou away from Leysritt before the other maid could do her little demonstration. "He's not here to be a butler either," Sella said, her eyes rolling. "So he won't be doing any of your work for you."

"Oh?" Leysritt said, her excitement visibly deflating. "But then, what is he doing here then?"

"I've adopted him," Kiritsugu explained, seemingly unconcerned at all by Leysritt's antics – a fact that unnerved Sella a little. Part of her wanted to tell him to be a little bit more protective, though the rest of her decided to keep a silent vigil instead. "He's my new son."

Leysritt kneeled down until she was at eye level with the boy, examining him closely. She stroked her chin for a few moments, before frowning. "Kiritsugu," Leysritt said with a frown. "Your son isn't very new at all. I would say he is at least five years old."

Suddenly, Kiritsugu's head snapped towards Shirou – who froze on the spot. Shirou was unable to move as Kiritsugu leaned over Shirou, an investigative eye taking a close look at his son. For a moment, Shirou wondered if there was something wrong with him, something that Kiritsugu hadn't noticed before. Finally…

"You're right," Kiritsugu said, standing back up. "He does seem a bit old. He must be nearing six now."

Shirou bowed his head, fidgeting with his fingers. "I-I'm actually seven," he admitted, even though he was afraid that the truth would only make things worse.

"Is that so?" Kiritsugu said cheerfully, a hand ruffling up Shirou's hair. "I suppose that makes you my new old son."

"I'm pretty sure those two cancel each other out," Leysritt said sagely.

"Ah, of course," Kiritsugu agreed with a nod. "Then, I guess that just makes you my son."

Shirou sighed in relief… before realizing they had been intentionally messing with him. "It's not fair," he muttered, trying to pout but not quite succeeding, "Playing around with me like that."

"It's not fair," Leysritt admitted, a small smile gracing her features. "But you'll get used to it."

"That's what family is," Kiritsugu explained.

"Don't you feel a little embarrassed saying something like that, Kiritsugu-sama?" Sella asked, crossing her arms.

"…a little bit."

XXX

Shirou had met Irisviel once before when he had been in the hospital, so he already knew to call her "Mama" when he greeted her, even if it was a little embarrassing. If he hadn't, Irisviel would have certainly glared at him – and that was a fate no man, let alone a boy, could endure, at least that was what Kiritsugu had said. The only thing apparently more dangerous was her mystic eyes of puppy dogs, which had apparently slain every opponent that it had been used against.

However, behind Irisviel was a girl he had never seen before, though Shirou had no doubt about who it was; he had heard a lot about her in the hospital after all. While Ilyasviel poked her head out curiously, she still continued to use her mother as a shield – observing the boy just as much as he observed her. Sheepishly, he raised his hand and smiled at her. In return, she ducked behind Irisviel, leaving Shirou just standing there awkwardly waving his hand.

"Now now, Ilya-chan," Irisviel said, gently stepping aside – leaving no cover for the cowardly Ilya at all. "That's no way to greet your new older brother, right?"

"Actually," Kiritsugu corrected, as he nudged Shirou forward for the second time today. "We figured out that the two cancelled each other out."

"Is that so?" Irisviel said, tipping her head to the side. "But that won't do," she said. "After all, Shirou-kun is bigger than Ilya-chan."

Shirou looked up at Kiritsugu, only to find the man already looking down at him. Once again, Kiritsugu had a thoughtful expression on his face. "I suppose you're right," Kiritsugu said. "I suppose he's the big brother then."

"That's right!" Irisviel said.

"So…" Ilyasviel said, furrowing her brow. "I have big brother?"

"Yes," Irisviel answered. "You can call him 'Onii-chan!'"

Shirou stared at Irisviel, though he spared a moment to glance to Kiritsugu. He should have expected this, from the way Sella and Leysritt had reacted, but…

"Mother, Father," Shirou said slowly, still not quite used to using those words. "It sounds like my sister wasn't expecting me."

"Of course she wasn't," Kiritsugu said with an impish grin. "It would have ruined the surprise."

"Surprise!" Irisviel shouted cheerfully, pumping her fist in the air. In the background, Leysritt mimicked her mistress' actions, while Sella gave the world a defeated shrug. As for Ilya, she still looked very confused.

On the bright side, that meant that Shirou had already found something in common with his sister.

XXX

Shirou's new sister was still wary of him, and the boy was sure that if the two of them were left alone he wouldn't know what to do with her. While he was worrying about this, though, Irisviel chose that moment to declare that it was time to go see Shirou's room.

There was one problem, though.

"We didn't prepare his room, dear," Kiritsugu reminded his wife.

"Oh?" Irisivel said with a gasp. "That's unusually negligent of us!"

"Perhaps you also wanted his room to be a surprise," Leysritt offered helpfully.

"That's it!" Irisviel said with a cheerful clap, retconning the past to fit the maid's suggestion in an instant. "That's exactly it. We didn't forget to prepare it at all, we just wanted it to be a surprise… and it wouldn't have been a surprise if we had done that!"

Kiritsugu smiled at his wife's seemingly boundless energy. "Well then," he said, running a hand through his hair. "Since we want to keep it a secret, you probably shouldn't spoil it for the boy by yelling about it in front of him."

Irisviel's eyes went wide as she realized her grave mistake... but it was okay, she could still fix this! Suddenly, she twirled around as though she were undergoing a magical girl transformation, and for a moment Shirou was sure that the white sundress she wore was going to change into something more suitable for fighting evil villains. However, Irisiviel's clothes didn't change, and in the end she simply ended her spin facing Shirou – her finger pointed at him as though it were a gun. "Please," she said with a wink, firing off an imaginary bullet. "Forget everything you heard just now, okay Shirou-kun?"

"…" Shirou stared at his mother for a moment, unable to find any words that would be able to be comprehended in the modern era. He was completely baffled by this woman; though he thought that he had figured out what to anticipate from her when she had visited him in the hospital, she had utterly surpassed his expectations. Finally, he simply gave a wordless nod, unsure what else he could do.

The brilliant smile she gave him immediately afterwards made him regret not answering her sooner.

"So it's settled!" she shouted as she grabbed Kiritsugu's hand, practically beaming. "Let's go set up his room!"

"Of course, dear," Kiritsugu said, as he was pulled his wife out of the room.

Then, just like that, his parents had left the room. Though Sella gave Shirou and Ilya a concerned glance, both of the maids shortly followed their mistress… and, before he knew it, Shirou found himself alone with Ilya.

As he expected, Shirou had no idea what to do with her at all.

XXX

A couple of minutes passed silently between them. It became even more awkward when he realized that it was Ilya's bedroom that they were in, and he wondered what would happen if he accidentally touched anything. Did she want him to leave? Had Ilya even accepted Shirou as her brother yet?

"Onii-chan," Ilya said softly, answering that last unspoken question.

"What is it?"

Cautiously, Ilya approached him – walking slowly as one would when she expected to run across some sort of trap. Shirou, for his part, remained frozen in place – not retreating, but at the same time unable to make any move at all. In a matter of moments, they were inches apart, with the little girl looking up at him with a curious expression.

"Is there something wrong?" he asked, shifting his posture uncomfortably a little.

Ilya frowned, before suddenly standing on the tip of her toes – a hand shooting out at his head. It was fast, unreasonably fast for a girl of her size, but even though she caught him off guard her hand didn't reach. In the end, she was too short to reach.

Shirou blinked. "W-what are you doing?" he asked, wondering if he had done something to make her mad already.

Ilya pouted. "I wanted to see Onii-chan's hair," she said.

"Is that so?" Shirou said, relieved. "Well then," he continued with a smile, kneeling on the ground so she could reach. "I don't really mind."

"Hurray!" Ilya celebrated, running her hands through his hair. He winced a little when she pulled a little too tightly at first – but he forgave her immediately when he saw her smile. When she calmed down, she had started to twirl some strands of hair between her fingers, though he couldn't really see how this was fun.

"Is there any reason you wanted to see my hair?" he asked, as she merrily continued to play with it.

"Oh," Ilya said, pausing for a moment. "I wanted to see you were a boy or a girl."

Once again, Shirou blinked, unable to understand the question. "You… you don't know?" Shirou asked, his pride as a man hurt a little. Sure, he was still little, but… he didn't think he looked like a girl.

"Well," she said, tipping her head to the side. "You don't have white hair like me or mama or Sella or Leysritt," she said, pointing at her own hair. "But you don't have black hair like Papa either! Your hair is red!"

Shirou chuckled. "Ilya-chan," he said, patting her on the head. "People aren't girls or boys because of their hair color."

"Oh," Ilya said, using her hand to cover a gasp. "Really?"

Shirou nodded. "Really."

"Interesting," Ilya said, stroking her chin. It was certainly a new discovery for her. "So then…what are you, Onii-chan?"

"I'm a boy," Shirou said. "If I were a girl, I would be your Onee-chan instead."

"Ah," Ilya said. "That makes sense! So then you're a boy like Papa!" she continued, pointing at Shirou with one hand.

"Yes. Yes I am."

"And I'm a girl like Mama," she said, using her other hand to point at herself.

"Well, yes."

"Then," Ilya said, bringing both of her hands together – forming the shape of a heart with them. "We can be a mama and papa too, right?"

"…no," Shirou said with a laugh, shaking his head. They couldn't do that, at least not with each other.

"Why not?" Ilya whined. "Papa and Mama always talk about how happy becoming Papa and Mama made them."

"Well," Shirou said, rubbing the back of his head as he tried to figure out a way to explain it. "We're already siblings, see?"

"Oh?" Ilya said, tilting her head.

"And becoming your brother has already made me happy," he said with a smile.

"Ah," Ilya said, smiling back at him. "Then… becoming your sister has made me happy too, Onii-chan!"

"Then it's settled. We'll always be brother and sister."

"Okay!"

XXX

Sella had been forced to make a tough decision when Irisviel and Kiritsugu had decided to go set up Shirou's new room. On one hand, she knew practically nothing about the boy, and she was concerned about what might happen if he were left alone with the young Ilyasviel. On the other hand… staying to watch the children would have meant leaving Irisviel and Kiritsugu to their devices. Sure, she could have sent Leysritt alone to watch them… but all things considered the other maid would have only made things worse, if she wasn't simply pulled into the chaos that the husband and wife were sure to cause.

In the end, she knew what she had to do. Even though she cast a regretful glance at the children, the ones she followed out the door were the graver of her concerns.

It started off innocently enough. There was an unused room on the second floor, empty save for some boxes that had been sitting there since the family had moved in there. Sella and Leysritt were tasked with putting them up in the attic. However, by the time Sella returned, she could already tell that trouble was about to start.

"Kiritsugu-sama," Sella said, staring at the object in her master's hand. "What… just what is that contraption?"

Kiritsugu followed Sella's gaze, eventually realizing that she was referring to what he was holding on to. "Isn't it obvious?" he asked, as he waved it around for her – as though its visibility had been the problem. "I thought it would be easy to tell what it was, honestly."

"It certainly does remind me of something," Sella said dryly, as she recalled what some of Kiritsugu's so called 'tools' were. "But… I am sincerely hoping that it isn't what I think it is."

"And just what is it that you think it is?" Kiritsugu asked, raising a brow. Once again, he looked at what he held, holding it up to eye level as he inspected it.

Sella pursed her lips as she tried to remember the exact name of the item. "A rifle," she finally said, with a frown.

"Ha!" Kiritsugu laughed, shaking his head quickly. "Don't worry, it isn't a rifle."

"Oh, is that so?" Sella asked, though she felt relieved that it wasn't a gun.

"It's a pistol," he explained, nodding his head. "In general, rifles will usually have a stock, a longer barrel, and are generally bigger in size than this," he explained – complete with accompanying gestures, which involved waving the handgun around a few times.

"But, in the end," Sella said with a sigh, rubbing her temples to ease away a headache. "Don't they all shoot bullets?"

"There's no need to worry about that," Kiritsugu said cheerfully. "These don't fire bullets."

"Really?" Sella asked skeptically.

"They fire paint!" he said. Then, to prove his point, he aimed at the wall and pulled the trigger of his pistol. A moment later, a small blue dot appeared on the otherwise perfectly white surface.

Sella stared at the dot for a few moments before she turned back to Kiritsugu with a sour expression on her face. "And… why does it fire paint?"

"Well," Kiritsugu said with a silly smile on his face. "What else do you expect a paint gun to shoot?"

"…let me rephrase that," she said, with a sigh. "Why do you have this 'paint gun' out?"

"Well," he said, pointing at the wall. "You can't really expect a wall to paint itself, can you? Not unless you use magic to animate it, of course."

Once again, Sella stared at the dot. That tiny, tiny dot that was all alone on the wall. "You... surely you can't be thinking of painting the entire room with just that pistol, are you Kiritsugu-sam?"

"Of course not," Kiritsugu said, scoffing at such a thought. "That would be ridiculous. The rest of you will be using some too."

"…"

"What? Is there a problem?"

"Can't we just use brushes, Kiritsugu-sama?"

"Well, that's what I suggested too," he said, nodding his head. "But, Iri said things would be more interesting this way, so she insisted this is how it should be done."

Sella suppressed a groan. "Of course she would."

"Don't worry," Kiritsugu said, giving her a reassuring smile. "It won't take that long."

"Why do you say that?"

"…do the words 'Paint Grenade Launcher' mean anything to you?" he asked, not that he really expected it too. She didn't even know the difference between a handgun and a rifle, after all. "Because Iri went to go grab one."

Yet, to Kiritsugu's surprise, Sella nodded. "Yes. They do," she said, rubbing her head. Regardless of what this 'grenade launcher' was, it was almost certainly going to be a headache for Sella, especially in Irisviel's hands.

XXX

So, there Shirou was, just starting to get along with his sister, when all of a sudden he heard the sound of something exploding. The house even shook a little, and for a moment Shirou had thought his heart had stopped beating. However, though it had caught him by surprise, for some reason it didn't bother Ilya at all.

…maybe it was just his imagination?

"Irisviel-sama!"

…then again, maybe it was real after all.

"Sorry, Sella!" he heard his mother apologize. "I'm still getting the hang of this."

Shirou glanced back towards the hallway that the adults had disappeared to where he had the hall had come from. For a moment, he wondered if he should check out if things were alright; whatever happened had caused Sella to shout out in distress. Then again, Irisviel would probably pout if he saw his 'surprise bedroom' before it was ready. Besides, he reminded himself, they were all responsible grownups, right?

A second explosion rang out, and with it followed another "Irisviel-sama!"

"Sorry!"

Okay, so maybe Irisviel was a little more carefree than he had anticipated. That didn't mean the others would cause any trouble.

"Leysritt!" Sella cried out, following another explosion. Just what were they doing that seemed to involve so much stuff blowing up?

"It looked like fun," the other maid explained.

"You…!"

Well, on the bright side, at least his father –

-BOOM-

"Kiritsugu-sama! Not you too!"

"Sorry. I'll make it up to you later, I promise."

…at that point, Shirou decided to give up. He wasn't sure what it was he was giving up exactly, but for some reason he definitely felt defeated.

"Is there something wrong, Onii-chan?" Ilya asked, looking up at him with a worried expression on her face.

"You… do you really not hear anything strange going on?" Shirou asked, wondering why she didn't seem bothered by all the noise. It was as if she didn't even notice any of it in the first place.

"Strange?" she asked, putting a finger to her lips.

"Yes, strange," he said, nodding his head. "It's… just listen."

"Okay, Onii-chan!" Ilya blinked, before nodding. Cupping her hand to an ear, she listened. Furrowing her brows, Shirou saw a very concentrated expression appear on her face.

Finally, about ten seconds later, another explosion came. "See!" he said, pointing down the hallway. "Didn't you hear anything strange?"

Ilya blinked, before slowly shaking her head. "No, not really, Onii-chan," she said. "It's just stuff blowing up again, right?"

"…"

XXX

A few minutes passed, which Shirou spent most of just listening to the various shouts and explosions while Ilya continued to play with his hair. Finally, Sella came walking back for some reason now covered from head to toe in blue paint except for her face. However, judging from the towel in her hand, which had a remarkably accurate depiction of Sella's frustrated expression, that too had been covered in some point, just wiped clean at some point.

"Come," she said, staring at Shirou. For some reason, she seemed to be angry at him… but just because it was his room they were setting up it wasn't like he could be held responsible for what the other adults had done, right?

"Come," Sella repeated, louder than before. "Or did you not hear me the first time?"

Shirou gulped, but quickly nodded – standing up and falling in place behind her.

"You too, Ilya-sama," she said to his sister – though with a far sweeter tone than she had used for Shirou.

"Okay, Sella!" Ilya said, pumping a fist in the air. Then she ran forward, excitedly jumping onto Shirou's back. "Let's go, Onii-chan!"

One way or another, Shirou managed to keep his balance – even catching Ilya before she could slide off of him. Giving off a weak smile, he was about to ask her what she thought she was doing… before Sella preemptively silenced him with a look.

"Yes," Sella said. "Let's go."

"O-okay."

And, like that, Sella started to walk back to where the others were and Shirou followed, all the while giving Ilya a piggy back ride. To be honest, he was afraid of what he would find at the end of the road – the source of Sella's irritation, as well as those explosions.

…finally, they reached a room at the end of the hallway. "Go ahead," Sella said, stepping aside. "Shirou-sama."

Shirou looked up at her before nodding. Making sure one hand kept Ilya from falling, he reached out to the handle with the other and twisted the doorknob. Then, with a deep breath, he pushed it open and stepped inside.

"Surprise!" Irisviel yelled energetically as soon as the boy stepped into your view. "Here's your new bedroom, Shirou!"

Shirou looked around. To be honest, he was surprised, even though he had known that they were getting it ready for him from the start. To be honest, he hadn't expected the room to survive whatever it was the adults were doings… and yet, here it was, with all of the walls somehow managing to stay in one piece.

The room was also blue. Very blue, actually. In fact, the only things in this room that wasn't covered in blue were the people inside it – except for Sella who stood in the door frame, who had somehow been the only one who had gotten caught up in the mess.

Still... it was intact and, more importantly, it would be his from now on.

Shirou let himself smile a little at that thought.

"So…" Kiritsugu said, grinning at the boy. "What do you think?"

"It's nice," he said, absolutely sincere. "But… didn't you guys miss something?"

"Eh?" Kiritsugu said, blinking. Quickly, he looked around, for a spot that had been left untouched – though he was unable to find none. "I'm pretty sure we got everything."

"Ah," Leysritt said with a clap. "We forgot the furniture."

Once again, Irisviel's eyes went wide as she realized the error that had been made. And, like before, she figured out that she could fix this. Twirling around again, she spun around before ending her spin facing Shirou – except this time instead of brandishing an imaginary gun she pointed a strange looking device at him.

"Please," she said with an innocent wink, "Forget everything you saw and heard just now, okay Shirou-kun?"

Then, she pulled the trigger. A second later, Shirou found himself covered in blue paint, just like Sella was.

"Ah! Sorry Shirou-kun," Irisviel apologized, rushing over to her son with a towel. "I forgot that I was holding a paint gun!"

"It's actually a paint grenade launcher," Kiritsugu corrected cheerfully.

On Shirou's back, shielded from most of the paint by her older brother, Ilya giggled. "Onii-chan, your hair is blue!"

"Yes, yes it is," Shirou agreed with a laugh, deciding to just go with the flow. "But I'm still a boy, by the way."

"Hurray!"

XXX

End of Chapter One.