Something was wrong A formless being survived its 'surroundings' if you could really call the void it inhabited it surroundings. Over the course of its sixty years of existence within this void it had never felt anything like this before and had such looked around to see whats up.
The feeling was strongest in the general direction of 'that' mechanism. The ones that would summon 'those' for 'that event'. Going over it the being noticed something strange. It looked like its recent foray into the outside world did affect the void a little. Well, not much left to do except watch the chaos unfold.
Lets see how the Humans like this.

*Ten years later*
Fill. Fill. Fill. Fill. Fill. Let each be turned over five times, simply breaking asunder the fulfilled time.
Let silver and steel be the essence. Let stone and the archduke of contracts be the three-branched road reaching the Kingdom.
– I shall declare here. Your body shall serve under me. My fate shall be with your sword. Submit to the beckoning of the Holy Grail. If you will submit to this will and this reason… then answer!
– 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! – From the Seventh Heaven, attended to by three great words of power, come forth from the ring of restraint, Protector of the Balance!

An explosion of power explodes from the center of the ritual circle attended by the twin tailed magus, sending her falling down onto her knees.
"Yes! That was flawless, there's no way I didn't summon the Saber class servant."
Rin's head popped up as if expecting to see her servant staring at her patiently.

There was no one there.

"What the?" she mumbled but was interrupted by a loud noise.
~CRASH~
"Oh, Come on" Exclaimed Rin loudly rushing up the stairs out of the basement. The door is stuck so she kicks it down. Only to be greeted by smirking Man in red and black sitting in the midst of her destroyed Living room.

Composing herself appropriately she asks "Are you my Servant?"
The man in red smirk widens "That depends, Are you my Master? Because you weren't here when I first looked."
"You make it sound like you're a baby bird, you don't imprint on the first person you see. As for proof of my mastership" Said Rin holding up her hand to show the command seals imprinted on it.
Sigh~ "Not the kind of proof I was looking for bu-"
"Argh". Rin doubled over in pain and suddenly her command seals expanded to twice its original size.
"Master! What's wrong?!" the Red wearing man exclaimed jumping up to run over.
~CRASH~ He never did as a second object fell through the roof directly on top of him.
"Oww…" Muttered the second object pitifully. Before rolling over and getting to his feet.
Surveying the area he noticed the guy he was currently sitting on.
"Oh! Dude are you Okay?"

"Gurgle burble" was the incredibly articulate response from the man on the floor.

By this stage Rin had finally had enough. "ENOUGH! Just what is going on here" she seethed expelling a dark Aura around her.

The blonde Knight got up and dusted off his armour "I am Servant Saber, I have come due to the bidding of the Holy Grail. Though I'm not sure why I was summoned as I have no real wish"

Rin stared her mouth slightly agape "If your my servant… then what is he" she said pointing down at the now recovered whitette.

He got up "Oh, I never introduced myself did I? Servant Archer had come to answer your call"

The two servants stood roughly a meter apart surveying each other. Rin stared at her command seals in shock.
"D-Did I manage to summon TWO servants?!" she said understandable shocked.
"It appears so, master" Archer wryly points out "you somehow broke the ritual so much it was actually beneficial for you."

Calming down, Rin turns up to look at her two servants. "Okay then. Can I know your names then?"
Archer spoke up first "Unfortunately I don't remember who I was in life. Maybe it's a side effect of the odd situation we find ourselves in now."

Rin sighed "Well this is a weird situation alright, I guess it only to be expected that some other things are weird as well. What about you Saber?"

The blonde straightens up "My name was Sir Jaune Arc, Leader of the Order of the Juniper. Slayer of the Dragon, D'draig, and Ancestor to the more famous Joan of Arc"

Archer whistled out his astonishment "That's a powerful card you've drawn Master. With both me and Saber you practically have the war in the bag"

Rin stares at him. "Oh? I thought you didn't remember who you were?"
Archer smirks "I don't. But if you managed to summon him as Saber I must be someone equally powerful."
Rin thought about it for a minute. Finally she nods her head "You make a point Archer. Now the first task for the both of you is… clean up my living room." both Archer and Saber face faulted at that "I'm going to bed" she adds before walking away.
As she leaves she hears Saber talking to Archer "Is she always like this. … is that a Yes? Okay"

Shirou thought that asking for a normal night was nothing special. Apparently he was wrong.
First Shinji had decided to skimp off on his duties to the archery club and foist them on him. Okay that's fine.
Then when he had finished he came out and saw two guys fighting, one in blue and one in red. That was weird but he was a magus and he could deal with it. Then when a white night got kicked by a guy who had a monkey tail was when he reached maximum weird stuff limit. He stepped back and accidentally broke a conveniently placed twig, which off course everyone heard. Realising all their attention was now on him he ran for his life. It was only par for the course when the Spearman in blue chased after him while the monkey guy held of the others. And that's how he ended up in this situation on the floor bleeding with a hole in his heart.
Really kind of a pathetic way to go really. He guessed it could be worse as his vision faded to black.

He woke up. That was unexpected. He was fairly sure he was supposed to be dead. Don't people usually die when they are killed?
Deciding not to question his survival he looked around to get his bearings. He was still in the school hallway, there was a puddle of blood around him and a Ruby Necklace beside him. Picking up the necklace he went to find a janitor's closet for a mop to get rid of the mess.

When he finally got home he collapsed to the floor utterly exhausted. What had just happened? There were two guys fighting, then there were four and then he had messed up by getting himself stabbed by a guy in full blue body tights. Seriously who wears those? A chiming of bells and a prickling of his instincts make him role to the left just barely avoiding the Blue guy from before.

"Wow, Kid" said the Spearman casually "You luck is either amazing or really shitty. I think this is the first time I've had to kill the same person twice."

Shirou was no sure to be more disturbed by, the fact that this man can talk so casually about death or the fact that he was right in front of him. Grabbing a rolled up piece of paper her barked his Aria to attempt to reinforce it.
"Trace, On!"
The glowing lines that show a successful reinforcement spread up the roll of paper.
The Blue Spearman's eyes opened a little wider. "Oh? A magus? That would explain how you survived. Still do you expect to fight me with that?"
His face twisted with rage "Don't Insult Me"

It was pure luck he managed to deflect the Spearman's first strike. He grunted and flicked his leg into Shirou's side sending him out of his window. Jumping out after him he swung his lance at Shirou who just barely blocked it with his reinforced paper rol. The force of it sent him skidding across his yard closer to his shed. 'Get to the shed and get a proper weapon' was his only thought. The Spearman did not seem to share his opinion charging forwards at a speed Shirou could barely track. As a last desperate move he unrolled his only weapon and used it as a shield to defend himself. He succeeded but at the cost of his weapon.
"That was a valiant effort kid but not enough." The Spearman said preparing to plunge his spear into the youth's chest for the second time that night.

Internally Shirou was panicking, externally as well.
In what he assumed to be his final moments he yelled his denial of reality to the man in front of him "My life was spared. My life was saved, so I'm not going to go die that easily! I have have to live and fulfil my obligations, and I can't do that if I'm dead! I'm not going to be killed in a place like this. For no good reason by a guy like you, who kills people like it's nothing!"

Suddenly a flash of silver blurred past him and knocked up the Spearman's Spear. It paused and turned to him.
"I ask of you, are you my master?" Said the Blonde Girl in armour with the moon shining inside from behind her.

When I felt the pull of summoning I was understandably surprised. By all right, the Church should've anything that could be used as a catalyst locked away in the deepest part of the Vatican. Having nothing better to do I obeyed its call and found myself here.
Falling...
From several thousand feet up.
… Having nothing better to do I reviewed the information given to me by my summoning. I was summoned above an island nation known as Japan. Specifically Fuyuki City. I have been summoned to fight for the Holy Grail, unfortunately it's not the cup that Jesus used -that would be something I would definitely would fight for- but rather a nigh-omnipotent wish granting device.

This 'Grail' has provided me with a bunch of information about the modern era, but that's not that important. What is important is that massive spike of bloodlust coming from directly below me!

Twisting my body I see a blonde girl protecting a red headed boy from Spearman in blue. They are being observed by a guy with a monkey tail. I can tell that except that for the red headed boy they're all servants. Though only the two male servants are activating my intuition meaning only they are dangerous. I pull out my bow and fire an arrow at each of them before putting it away and preparing for landing.
Look out below!

*2 minutes earlier*

The battle between Saber and Lancer while short was incredibly intense. Every thrust and parry was little more than a blur to the eye. After gaining some distance Lancer stopped and called out.
"Tell me Servant, that invisible weapon you're holding, it is a sword right?"
Saber pulls a small smirk "Who knows? It could be, but it could also be a axe, a polearm or even a bow."

Lancer's glare grew even harder "Very funny swordswomen, as this is our first meeting I don't suppose we could call it a draw?"

Saber stood resolutely "I think not. You will fall here, Lancer!"

Lancer tipped his head downwards "Is that so? Damn, my objective was to simply observe…"

His spear erupts with prana and bloodlust, and his head comes back up to glare at the opposing swordswoman. "I'll have your heart!" He begins his charge forward only to leap back and watch an arrow slam into where he was just an instant ago. "What the!"
A red comet smashed into the ground, causing a massive crater where it landed. The object unfurled from a ball into a figure whose face and body was obscured by their cloak. Swinging their arm out, a scythe that was bigger than they were materialised.
"Backup?" growled Lancer The figure merely offered a smirk and preparing their scythe for combat. Then they stopped "If you're waiting for your own backup, you should probably leave. You dodged, he was not so lucky."
Glancing towards a nearby rooftop he cursed in Gaelic. He then tilted his head as if listening to someone speaking.
"Fine" he growled "Well Saber, Archer my cowardly master has ordered my to retreat for the time being. He thinks fighting two servants at a time is too much for me alone to handle. Just be prepared that if you are to follow me I will no longer hold back."
In two leaps Lancer exited the premise of the building towards the direction where he looked to earlier.

The two remaining servants stared at each other.
Saber sighed "I thank you for your assistance Archer but I suggest you return to your Master now. I will not fight you tonight but we are still enemies."
Archer pulled down the hood of her cloak revealing her red eyes. "Nope" she stated with certainty.
Saber frowned and took a stance with her invisible sword "If you don't I will be forced to fight you."
Archer met her gaze unfazed and started to walk towards her weaponless "Nope"
Saber lowered her weapon confused by the red cloaked servants antics "And why not?"
Archer stopped right in front of her "Because silly Saber, we have the same Master."

The two Servants turned in sync towards their shared master who just stood there slack jawed. "I have the feeling that we're going to get along swimmingly." Said Archer with the straightest face possible.

AN.
Welcome to the Authors Note where, I, the Author will bestow his most wonderful wisdom upon you. In all seriousness though this is my first attempt at actually writing a FanFiction. Sure, I've come up with dozens within the confines of my own brain but this is the first I've actually managed to get down into print. So expect updates to be slow, periodic and not that great really. Anyway I decided to write this because I feel that there is a critical lack of Fics like this in this section. Sure we have fics were RWBY characters replace the ones from the Nasuverse, we have Fics were Fate/ Characters end up on Remnant and we have Fics where RWBY characters gain the Fate/ Characters Powers. But what we have a critical lack of is Fics that bring the Rwby characters into the Nasuverse as servants or other. Anyway here's a random Omake that I thought of while making the premise of the Fic, Hope you have fun with it.
Feedback would be appreciated and negative opinions will be ignored.
Lost Lurker Leaving Lengthily
(I had honestly more fun writing that then I probably should have)

Omake 1 , Gil meets Anti Gil
Gilgamesh was confused, this was not a common occurrence. Not that Gilgamesh didn't get confused, but that the source of his confusion was still in functioning condition.
"So you are saying, that you're a servant that I summoned just by existing" he said "Uh huh" said the Red headed servant in front of him.
"And you have your own servant that you can summon" Continues Gil with his eyebrow twitching. "Yep" the servant agrees popping the P.
"And I can't kill you because our lives are linked"
"Well that and this shield I've put between myself and this barrage of weapons. So if you could stop that I would be much obliged" Roman helpfully points out.
Gil's fist clenched tightly "What I really want to know is why you have a shield that belongs to me?"
Noticing the look on his attackers face Roman quickly stated "Oh, well you see it's a long story that involves a Little girl riding a giant wolf, A dare, A witch, and the theft of everything little thing of value in the world."
Gilgamesh's face contorted with rage "THAT'S IT I'M KILLING YOU FILTHY MONGREL."
Pulling out Ea he starts to get it ready but is shocked when it disappears from his hands.

"Wow, this is a fancy piece of work" Roman says while holding the most dangerous weapon ever created casually in one hand Gil, understandably had a moment of panic "Mongrel, whatever you do don't push the button on the hilt"
"Oh, you mean this one?" Roman asked with his hand pressing it all the way down.
And that's how the world was destroyed
Bad End