Hello all Storm here with a new story! Here we'll be seeing a first (I think) with Naruto being born in the Fate/Stay Night world and taking part in a Grail War. So, without further ado.

I own nothing

'Most kids my age would be outside, playing together or simply hanging out. But here I am, mopping.' Thought nine-year-old Naruto Uzumaki, sighing as he mopped the deck of his family's home.

For as long as Naruto could remember, his parents have kept him sheltered from the outside world, never letting him go anywhere or let him play with other kids his age. The most Naruto's ever gone outside was to complete his chores, and even then, it was limited to only the backyard. Though Naruto could partially understand the secrecy, given they were a Magus Family. With all Magus Families being known for their secrecy and hardly interact with outside world, or other people that aren't in the know.

But with the lengths that his parents went, Naruto felt they took the secrecy way too far and were close to reaching the point of isolationism. With how out of the way they are from towns and cities, along with the Boundary Fields his parents have set up around the house. The only reason they weren't complete isolationists, like the Einzbern Family, was that his parents still left the manor at times.

'But here I am, unable to leave.' Naruto thought, a little annoyed that while his parents could still leave if they wanted to, he was stuck staying home no matter how many times he asked if he could leave.

Sighing and shaking his head, Naruto soon finished before going back inside, deciding not to focus on such thoughts for the time being. Before he went to go find his parents so he can continue his Magecraft training, knowing he'll eventually be able to finally leave and learn at The Clock Tower.

Walking through the manor, Naruto soon found his parents in the living room. But before he could approach them, the Uzumaki stopped when he heard them talking.

"-I don't like this; he was so excited to be able to go to The Clock Tower." Said Kushina as she looked at Minato in worry, with the man sighing and shaking his head.

"I know, but it just seems like the safer option to have him be homeschooled, rather than attending The Clock Tower." Minato replied, while Naruto's eyes widened from where he was hiding at hearing this.

'They…they're not going to let me go to The Clock Tower? They're going to just keep me here?' Thought Naruto, not believing that his parents were now taking away his one chance to finally go out into the world and interact with people.

Part of Naruto wanted to reveal himself and finally demand answers on why his parents were basically keeping him locked up in his own home. Refusing to let it go, now that they were considering having him homeschooled. Even willing to threaten to find a way to sneak out, if that's what it took to get some answers.

But another part stopped him from doing anything rash and kept listening, wanting to see if he'd get some answers by listening to what they're saying.

"I don't like this; we're basically turning our son into a prisoner in his own home. How will he even know how to interact with other people, when he can't even get the chance to meet anyone. What if…what if he starts hating us for keeping him locked away?" Kushina said while looking ready to start crying at the idea of Naruto hating them for keeping him inside and hidden away, with Minato putting a hand on his wife's shoulder.

"I know, I don't like it either, but it's for the best. If other Magus Families or the Mage's Association find out about him, there's no telling what they'll do. For his own safety, no one can find out about Naruto." Said Minato, as Naruto grew confused and worried when he heard that.

'No one can find out about me?' Naruto thought, not understanding what his parents meant by that, since while he knew they didn't let him go outside and interact with people, he always assumed that it was known they had a son.

But now apparently, they weren't just keeping him inside, they were keeping his entire existence a secret from everyone. But why though, he hasn't done anything bad, he's able use to Magecraft and possessed Magic Circuits, so why would his parents want to keep his existence a secret?

And why would the other Magus Families or the Mage's Association care about learning about him, Naruto knew there wasn't anything different about him than other Magus children.

'Could I…could I have really been…adopted? Is that why?' Naruto thought worriedly, since that's really the only thing he could think, knowing how Magus Families and the Mage's Association preferred keeping the supernatural a secret from the rest of the world.

Maybe that's why, and they wouldn't like it if his parents adopted a child with no connection to the supernatural and awoke his Magic Circuits, as opposed to having a child of their own. Or adopting a child from another Magus Family.

Naruto wasn't sure what the reason was, or why his parents chose to keep his existence a secret, but he was determined to try and find out.

*Timeskip-Eight Years*

Eight years have passed, since Naruto learned that his parents had been keeping his existence a secret from the rest of the world. With the Uzumaki having since begun trying to find out just what they had been keeping from him. Though knowing he had to be careful with his searching, otherwise his parents would keep a closer eye on him than they already did.

Leading Naruto to wait for whenever his parents left the manor, giving him the time he needed to begin searching everywhere for any clue as to what they're keeping from him. While making sure to put everything back the way it was, when he was finished and before they returned home, as to not arouse their suspicions.

It took Naruto nearly two years, but eventually, he had finally managed to discover just what his parents had been keeping from him and why they were keeping his existence a secret. And when he finally did find out why, Naruto really wished he hadn't, as now he could barely even look at his parents the same way.

While they still loved and cared about him, Naruto had trouble being around them after knowing what he did now.

Something his parents seemed to pick up on, making them believe that Naruto was actually starting to hate them for keeping him inside and homeschooling him. Making them start doing everything they could to make him feel more comfortable at having to stay home, getting several different things to have some hobbies and activities. Such as manga, anime, and video games, with Minato and Kushina not minding the use of technology, like most Magi Families since it made Naruto happy. Along with being some of the more progressive Magi that were willing to advance themselves, rather than become stagnate.

It did help Naruto get closer with his parents again, as he and his mother both developed a fondness and enjoyment with manga and anime. While he and Minato both enjoyed some modern sports, with Naruto especially enjoying martial arts. This leading to Naruto wanting to learn Mixed Martial Arts and Close Quarters Combat. Wanting to be able to fight enemies up close with either his fists or with any weapons he had, something his parents allowed him to start learning.

And thanks to Naruto playing video games, and learning about important figures in the Supernatural World, he's also shown interest in learning to use firearms. Like the Magus Killer Kiritsugu Emiya, after learning about the man and how he was feared by dozens of experienced Magi. With everyone being relieved when news spread of his death, knowing they wouldn't have to fear him coming after them. Making Naruto wish to learn to use guns like Kiritsugu, knowing they'll definitely be useful against other Magi, especially if they believe another Magus Killer is appearing.

Though he'd also have his own moral code and sense of honor, given how the Magus Killer was also known to kill anyone that got in his way of his target. Along with not caring for the collateral damage as long as the mission was complete.

The other weapons he used included a katana and twin wakizashi for his CQC fighting style, along with his guns. With him having also learned some ancient and rare forms of martial arts, as a means for him to have something unexpected and unpredictable to fall back on, as well.

But while Naruto had started bonding more with his parents again, it was still hard for him to interact with them now that he knew the truth. Though things soon changed, the day that they all saw the Command Seals appear on the back of Naruto's right hand, knowing what they meant.

Naruto had been chosen as a Master for the Fifth Holy Grail War, which will soon be taking place in just a few months.

Currently, Naruto stood in the attic of the manor, standing in front of a Summoning Circle, along with the catalyst he was using to summon his Servant. A fragment of the Round Table itself, knowing such a thing would guarantee him summoning a Knight of the Round Table, perhaps even King Arthur himself. Naruto knowing his parents were hoping he summoned Saber, regarded as the strongest Servant Class, giving him better protection from the other Masters and Servants. He personally just hoped that whatever Servant he summoned; it would be one he could work well with.

Shaking his head, Naruto clenched his fist and held it up, before he started the Summoning Chant.

"Let silver and steel be the essence."

"Let stone and the archduke of contracts be the foundation."

The Summoning Circle glowing in response to Naruto's words as energy began arcing around it.

"Let red be the color I pay tribute to."

"Let rise a wall against the wind that shall fall."

Soon enough, the glowing of the Summoning Circle began to become more intense. Soon turning into a bright light emanating at the center, as the Servant began manifesting, start with their feet.

"Let the four cardinal gates close."

"Let the three-forked road from the crown reaching unto the Kingdom rotate."

"Let it be declared now; your flesh shall serve under me, and my fate shall be with your sword."

More and more of the Servant's body manifested, with its legs and waist already formed, while it's torso began manifesting as well.

"Submit to the beckoning of the Holy Grail."

"Answer, if you would submit to this will and this truth."

"An oath shall be sworn here."

"I shall attain all virtues of all of Heaven; I shall have dominion over all evils of all of Hell."

With those words, the majority of the Servant's body had soon manifested, before the entire area was engulfed in a bright white light.

"From the Seventh Heaven, attended to by three great words of power, come forth from the ring of restraint, protector of the holy balance!"

When the light faded, Naruto looked at the Servant he had summoned, seeing they were wearing heavy steel plated armor with red accents, a horned helmet, and wielding a large broadsword with a matching color scheme.

"Who are you?" Naruto asked, unable to recognize who this Knight was, but could obviously tell they were in fact Saber.

"I am Mordred Pendragon, son of the King of Knights. Now I ask of you…" Said the now revealed Mordred before their helmet folded back, revealing to Naruto's shock, a young teenage girl with her pale blonde hair held up in a ponytail and with two braids tied on either side of her head, bangs framing her face, bright green eyes, and a smirk on her face.

"…are you worthy to be my Master?" Mordred said, as Naruto looked at her with wide eyes.

"But…you're a girl." Said Naruto, confused and shocked that the Knight of Treachery was in fact a girl, yet referred to herself as King Arthur's "son".

Though Naruto soon found a sword pointed at his neck, as Mordred glared murderously at him at the mention of her gender.

"If you value your life, you will not say anything about my sex ever again." Mordred threatened, abhorring any mention of her gender and anyone bringing it up around her, with Naruto being momentarily stunned at the sudden threat and attack, having not expected it, before he smiled teasingly at the Knight.

"Alright, I won't say anything about your sex…Mordred-chan." Said Naruto, making Mordred narrow her eyes in rage at him.

"…You have five seconds to beg for mercy, before I cut off your head." Said Mordred now even more pissed off.

"Why? I didn't say anything about your gender, I just called you Mordred-chan. Since that's clearly what you are Mordred-chan." Naruto replied teasingly, with the girl's eye twitching rapidly.

"Do you even realize I could kill you before you even blink, with one arm tied behind my back?!" Mordred demanded while wondering if her Master is simply insane.

"Yeah, but you won't. Since I am your Master, and it'd be nice if we could be friends Mordred-chan." Said Naruto, making Mordred scowl since she had to admit he was right, she can't kill him since he is her Master and her only link to the living world.

Plus, her own status as a Knight prevents her from striking him down, no matter how annoying he is.

"Fine, I can't kill you. But that doesn't I can't leave you in a crippled and vegetive state, since I only really need you supplying me with Magical Energy. Nothing about you needing to be responsive." Retorted Mordred with a dark smile, while Naruto remained unphased, having seen through her bluff.

"Aaaah, but then we wouldn't get to hang out and get to know each other. Besides, it'd be pretty boring if you had to go and do all the work alone. And that wouldn't be very fun now would it, Mordred-chan." Naruto said sounding genuinely upset, while the Saber-class Servant's frustration was reaching it's peak before she lowered her sword.

"Be thankful, since if I was any other Servant, I would have killed you already, consequences be damned." Mordred said, knowing that other Servants wouldn't have hesitated to kill Naruto for such disrespect, though the Knight of Treachery was silently starting to begrudgingly respect her new Master, since he had to be very brave to tease her like that.

With Mordred taking the moment to get a good look at her new Master.

Naruto had spiky dual colored blonde and red hair, with it being red around the edges of his hair and blonde on the inside, pale skin, dark blue eyes, and three unique whisker marks on his cheeks, reminding Mordred of a fox. Wearing black, red, and white sneakers, black pants with a red and black belt with a silver circular buckle, a dark blue shirt, and a burgundy red jacket with a black collar.

"Then I couldn't have asked for a better Servant. And don't worry, I'll only call you that in private, so no one finds out who you are. I'll just call you Saber-chan when we're around others!" Said Naruto, smiling at his Servant, while Mordred took a deep breath before her helmet folded up around her head.

"…Let's just go." Mordred muttered, wishing to find some other Servants that she can take her aggression out on.

Nodding, Naruto and Mordred headed downstairs, with the whiskered boy tensing slightly at seeing his parents. With Minato and Kushina looking at their son, seeing him also accompanied by his new Servant.

"So, this is your Servant?" Minato asked rhetorically, with Naruto nodding nervously.

"Uh, y-yeah, this is Saber. I-I'd tell you th-their name, b-but th-they're kind of…private about it." Replied Naruto, with Mordred looking at him with a raised brow at the unexpected nervous tone in his voice and the rather insecure expression on his face.

A far cry from how he was unphased by her threats and happily teased her as if she wasn't holding her blade to his throat.

"Naruto, are you really sure you want to compete in the Holy Grail War? There's no telling who else will be Masters in it, or what other Servants will be summoned." Said Kushina, worried for her son, especially with how the last Holy Grail War turned out and the destruction that followed at the end of it.

"Y-yes, I want t-to do this. I'll be s-sure to stay safe, besides…I-I can handle myself and will have S-Saber." Naruto said.

'Seriously, what is up with him?' Mordred thought while looking at Naruto, wondering how someone brave enough to tease her to her face, could suddenly turn into someone who looks like they'd be afraid of their own shadow.

As she knew it definitely wasn't pre-war jitters, since Mordred could see from his physic that her Master wasn't lying about being able to handle himself.

"If you're sure, then all we can do is say, good luck and do your best Naruto." Minato said, with Naruto nodding hesitantly.

"Th-thanks and I-I wil-will. A-and I pr-promise to bring the Holy Grail t-to the U-Uzumaki Family." Replied Naruto before waving to his parents, as he and Mordred quickly left the manor to begin making their way to Fuyuki, where the Fifth Holy Grail War would be held in a few months.

Once the two had left, Kushina started crying with Minato wrapping an arm around her shoulder to comfort her.

"We knew he'd be leaving the manor, eventually. Him being chosen as a Master only sped it up sooner than we expected. And we did our best to prepare him for the outside world, before he was chosen as well. Plus, Naruto can handle himself against other Masters and he summoned Saber, so he won't have to worry about the other Servants either." Minato said.

"It's not Naruto being killed from enemy Masters or Servants, I'm worried about. But what if any of the Magi in Fuyuki learn about his origins and it gets back to The Clock Tower?!" Said Kushina, knowing the extreme methods that some Magi take to reach the Root, the source of all events and phenomena in the universe, a goal that all Magi have been working towards all their lives

With some taking more extreme measures than others to reach it, with the Holy Grail War being proof of that.

"We just need to hope that things will work out." Minato stated, knowing that's all they could.

*Later-With Naruto and Mordred*

It wasn't long before Naruto and Mordred arrived in town, with the first thing that they did was get Mordred some normal clothes, since the Knight refused to stay in her Spirit Form the entire time. And she only had her attire that she was summoned in, so they had gone to a store to get her some modern attire.

With Mordred now wearing black ankle boots, black short shorts with a red and white waistband while leaving her legs exposed, a fishnet crop top exposing her midriff, and a short, red hoodie that with black bands around the upper arms and left the bottom part of her top and breasts exposed.

"Aaah, these clothes are amazing Master!" Mordred said, pleased at her new attire and that she didn't have to stay in her Spirit Form and could walk freely, while Naruto looked at her with a raised brow.

"You know, for someone who doesn't like their gender being brought up, you don't seem to mind wearing something that's revealing and clearly shows you're a girl." Stated Naruto, with the Knight giving him an annoyed look.

"It has nothing to do with my gender, it's simply easier to fight in clothing like this. Besides, I'd look good in anything." Mordred retorted while crossing her arms under her bust, with a smirk on her face.

"…Right." Naruto muttered, seeing that while Mordred didn't like her gender being brought up, she certainly had less qualms about showing off.

"Now, this Holy Grail War, it's different from others?" Questioned Mordred, with Naruto nodding in response.

While a normal Holy Grail War usually consisted of seven Masters and Servants, this one was different in that no one was sure how many Masters and Servants there would be. No one knows what could have caused this, but many have come to the conclusion that it may have something to do with how the Fourth Holy Grail War ended.

"Yeah, we don't even know the exact number of Masters and Servants there will be. Could still be seven, could be seventy for all we know. So it'll definitely be more dangerous than usual." Naruto replied, with Mordred nodding in agreement.

"And…there will be a chance that other Sabers will appear, right?" Mordred asked.

"Most likely there will be some other Servants that have the same Class, so there's a chance we'll encounter other Sabers." Answered Naruto, with the Knight smirking wickedly at this.

"Good to know." Mordred said, hoping she'll get the chance to encounter the only other Saber that she's interested in, and then crush them.

Though Naruto soon looked around in awe, when they reached the train station, taking in the sights and sounds of everything around him, something Mordred noticed.

"You're acting like such a child, Master. Acting like everything is the most amazing thing you'll see. What? Never seen a train station?" Mordred said tauntingly, deciding to get some payback for his earlier teasing.

"You'd be the same, if the Holy Grail didn't upload information of the modern world to you, Saber-chan. Maybe you'd try fighting a train, thinking it was a dangerous beast if you didn't." Naruto replied teasingly, with Mordred fighting the urge to strangle him, only to stop when he gained a solemn expression on his face.

"This is actually my first time going outside of my home. My entire life, my parents kept me locked away, not letting me interact with people, go outside, or even attend The Clock Tower. So yeah, everything I'm seeing now, I'm seeing it all for the first time rather than just hearing about it or seeing it through pictures." Naruto said, making Mordred flinch lightly at seeing how tactless her previous remark was, along with feeling empathy for Naruto, knowing what that's like.

"…I was raised by my mother, my entire life, in secret. Never even knowing who my father was. All I knew was because of her, and that I had to keep my identity hidden from everyone and not let anyone see me. Even when I became a Knight of the Round Table, I still had to hide who I was, never being able to remove my helmet or armor, having to be the perfect Knight for the perfect King. So, I can understand the feeling of not getting a normal childhood and being locked away by a controlling parent." Mordred admitted, making Naruto look at her in surprise before he smiled at her.

"I guess I really did get the best Servant I could have asked for." Stated Naruto, making Mordred smirk.

"Of course I'm the best. And you are…an adequate Master." Replied Mordred, with the whiskered teen laughing lightly.

The two soon entered the train station, waiting for the train that'll take them to Fuyuki. Knowing once they get there, then it won't be long before the war begins.

So, what did you think, good. Yep Naruto has lived a rather sheltered life due to his parents keeping inside their home, something Naruto eventually learns the reason as to why and why they even kept his existence hidden from everyone. Before we get a timeskip with Naruto being chosen as one of the Masters of the Fifth Holy Grail War and summoning none other than the Knight of Treachery herself, Mordred Pendragon! Along with Naruto teasing her with nicknames, while Mordred is unable to attack him due to her honor, before they set out for Fuyuki, along with the reveal that this Grail War is different as it's not being set to seven Masters and Servants, something Mordred is eager for to face a certain other Saber. Along with Naruto and Mordred bonding over their shared sheltered lives, seeing how similar they've grown up together. So, review if you liked go away if you didn't.

Storm out