Disclaimer: I do not own anything in this X-over. Fate/ stay night is owned by Type-Moon while Young Justice is owned by DC and Warner Bros. Animation.

+Ryuudo Temple, top of Mount Enzo and at the outskirts of Minami Town, Fuyuki City+

As the light of dawn slowly came to be, three figures stood atop the temple grounds, all of them staring at the spot where the manifestation of a grail containing massive amounts of prana and a corrupted being called Angra Mainyu once had been prior to its destruction by the third figure, the 'Once and Future King', the girl who wields the legendary holy sword Excalibur and the Saber summoned for the fifth Holy Grail War, Arturia Pendragon.

Panting at the drain on her magical core from using her Noble Phantasm, the King of Knights stared at the exhausted form of her master, Emiya Shirou, who was coincidentally the adopted son of her former master in the previous Grail War. She was initially surprised upon learning of it when the redhead told her that after their first battle with Berserker and the subsequent alliance between him and Tohsaka Rin, but eventually thought little of it even as the Second Owner of Fuyuki interrogated him about it.

Sure, she detested her former master for what he done to her but it would be petty of her to redirect that hate (*cough*Illyasviel von Einzbern, bless her soul*cough*) to someone who had no fault over the actions of his adopted parent. Then, there was also the fact that he revealed the true reason of why the Magus Killer did what he had done.

The Holy Grail, the reason why she made a pact with the world to obtain it as she was on the verge of death during that fateful battle in Camlann, the very thing that could have granted her wish. It had become a twisted, corrupted mockery of what it could, should, and would have been. If it were to grant her wish then what she desired would be tainted, countless lives would be lost, and the possibility of a great evil being unleashed upon mankind was very, very real.

Arturia would have lost her will to fight then and there, realizing that everything would be pointless if she even tried to win until Shirou told her what he had been preparing himself to do for the past ten years. He wanted to end the Grail Wars and do what Kiritsugu couldn't do.

He wanted to become a True Hero of Justice and save everyone he could.

It was strange (and somewhat alarming) when one thought of his ideals because of one simple fact that she had personal experience on. Not everyone could be saved. The many things she had sacrificed to keep her country afloat were a clear example of that and yet she still had failed her people. It was just how the world works.

And yet…

She remembered her master smile as he acknowledged the hypocrisy of his borrowed ideals. "I know very well the impossibility of his ideals more than anyone, Saber. Pursuing those ideals is insane and no normal person or Magus would even dare try doing so without losing something in the process. But I already lost who I once was in the fire from the last Grail War. I still remember those that I did not help just to live. I would have died if it were not for the man who saved me. I guess you could say that this is my way of atoning for the lives that were lost. I know that I can't save everyone but if there's even one life worth saving, I won't stop for the sake of my borrowed ideals."

He extended his hand towards her, the command seals on it left unused. "As such, if you can't find it in yourself to fight for your wish Saber, please fight with me to end the Grail Wars so that no one would have to go through what I experienced."

And accept it she did, together they fought against the other masters and servants over the past days since her summoning. Gaining victories and allies, experiencing loss and the death of his adopted sister but most important of all, despite the odds stacked against them, her, the Servant Saber, and him, the Wrought Iron Magus, found comfort with each other and fell in love.

That was something that earned them the ire and anger of the third figure, the first hero, the owner of a thousand Noble Phantasms, Gilgamesh. The same Gilgamesh who she fought in the previous Grail War and had still been alive after ten years was now seething in rage, his golden armor dented in places and his face marred by a fresh wound that went diagonally from his forehead to his left cheek. It was a deep cut that she knew was given to him by her master, if the blood dripping from the redhead's white falchion was any indication.

"You plebeian!" shouted Gilgamesh. "You dare wound me?! The King! You're just a fake!"

Shirou stood straighter even if she could see that he truly was exhausted, pointing the black falchion he held in his left hand to the red-eyed blonde as his golden eyes took a steely glint in them. "As I've told you before, even a fake can surpass the original. And yes I would dare you bastard! You would kill everyone in the world with the grail! You killed my sister! You hurt Sakura and Rin! You tried to take Saber away from me! I. WILL. KILL. YOU."

Arturia felt proud for her master as he showed his defiance to the King of Uruk, which quickly turned to dread upon seeing a golden ripple appear next to the king's right hand, a familiar hilt of a weapon that could destroy a world coming out of it.

"YOU MONGREL! I WOULD PERSONALLY MAKE SURE THAT NOTHING WOULD BE LEFT OF YOUR COUNTERFEITING EXISTENCE!"

"SHIROU!" She was already on her way to her master as she shouted his name, utilizing a quick burst of prana to propel herself in front of him. With her hand outstretched, she prepared herself to call forth the copy of her beloved sheathe Avalon that was given to her by the redhead, only to remember that it could only shield one person at a time.

Before Gilgamesh could hold Ea in his hand, Kanshou and Bakuya, the married swords that were the preferred weapons of her master and his Counter Guardian counterpart were thrown, forcing the king to dismiss his gate to avoid them lest he lose his head.

Arturia then felt Shirou's hand in her own, and looked at her left to see him beside her with Caliburn traced and held in his left hand. He gave her a nod and she gripped his gloved hand tighter, the message not needed to be said.

Hands linked and swords raised, a war cry escaped their lips as they charged at the King of Heroes who had opened his Gate of Babylon once again to claim Ea.

They were within striking range now and with no amount of time to charge it, the king swung the not-a-sword to force them back. It was in vain though, as Shirou used the traced Caliburn to parry it at the cost of his projection's destruction while her sword was raised for an overhead slash.

This was it. With Kotomine Kirei dead and the Grail destroyed, the war would end with Gilgamesh's death.

It definitely would have been the end had something not interfered.

A black blob appeared between the three before the Sword of Promised Victory could cleave through the king's metal, flesh and bones, stopping it cold. Silence reigned for a few seconds as they stared at it until they all felt the sudden suction as the blob grew in size and the feeling of corrupted prana returned. The Grail wasn't done with them yet it seems.

Try as they might though to not get sucked in, it was like fighting against a black hole. And it is well known that not even light or a star could escape from a black hole's pull.

Seeing the futility of escape, Arturia felt her master embrace her tight as the screaming golden king was sucked in first while it would take naught but a second for them to suffer the same fate.

"Together." He whispered to her as they could no longer fight the pull and got sucked in by the darkness, leaving only the destroyed temple as the black blob disappeared along with them.

Servant Archer, the Counter Guardian EMIYA, gritted his teeth as he saw the place where the blob that sucked in his (not exactly) past self, Saber, and the arrogant king of heroes to who knows where once existed. Shit.

Archer what happened? Rin Tohsaka, his Tsundere of a master, asked through their link.

They're gone Rin. They're all gone. They got sucked in by an anomaly from the grail.

WHAT?!

I said that they got sucked in by an anomaly from the grail. An act out of spite I suppose. Archer told her as quickly began to make his way back to the Emiya household, where his master and her (now worm free but still unstable in terms of her magical energy and possibly sanity) sleeping sister, Sakura Matou, were recuperating.

Crap. What do we tell Sakura? Or Fujimura-sensei? She asked worriedly, making him shrug.

I'm sure you'll figure something out. He replied before choosing to ignore his master's calls until he would arrive.

+Unknown/Hidden Location+

Shirou was not what you'd call a normal person. He only survived the unholy fire that came to be from the contents of the tainted Grail ten years ago thanks to Emiya Kiritsugu and Avalon. He had lost who he was to that inferno. Learning the reason why that inferno happened was what forged his resolve to be trained by the Magus Killer (with help from a reluctant former master/loyal subject of the King of Conquerors) before his death and thus inherited the man's ideals…and as much as he didn't want to admit or use, he too knew how to use the methods that Emiya Kiritsugu had.

Despite being nothing more than a third-rate Magus, his overspecialization with what magecraft he knew and the skills he had as a warrior was everything he needed in the Grail War. So when his consciousness was returning and that he felt that he was lying on something soft while the scent of the air practically reeked of magical energy, his reaction was to stand straight immediately from the couch, trace his favorite pair of swords, and point them at the surprised old man holding a cane.

The Magus Killer made it a very important lesson for the redhead that if he was in someplace that he did not know of and was possibly in a lair of a magic user, he always should be ready to fight for his life.

In other words: Paranoia good, unknown bad.

His eyes roamed his surroundings, revealing a dark western room that was actually quite comfortable. A brick fireplace was burning with a fire and a large portrait of a smiling woman was over its mantle. The walls were lined with filled bookshelves while furniture was present in the room.

It was lovely but he knew he was still in possible enemy territory so he looked back at the old, well-dressed man with short grey hair who had not moved an inch from where he stood, looking at Kanshou and Bakuya with curiousity.

"Who are you?" Shirou asked in English, mentally thanking Waver Velv–err, Lord El-Melloi II for the advanced English lessons he received from him. "Where am I?"

The old man raised both of his hands as a sign of peace. "My name is Kent Nelson. As for where you are, you are inside of my tower, the Tower of Fate. Do not worry; I mean no harm to you or your companion in the next room."

Arturia? Shirou gasped. "Where is she?"

Kent made a motion with his hand for the redhead to follow him as the fireplace dissolved and revealed a possibly endless maze of stairs not unlike that of M. C. Escher's famous lithograph, making Shirou gape at the sight.

"What the heck kind of bounded field is this?!" He shouted in Japanese as they walked inside.

"Bounded field?" Kent asked before scowling. "Oh dear, tell me my boy, did you come from the multiverse where a Kischur Zelretch Schweinorg exists in?"

"Uhh…yes?" Shirou replied, dismissing his blades as he could feel that Kent really did mean no harm. Most magus worth their salt (or not) knew of the Old Man of the Jewels and preferred not to associate with him because of a simple reason even if they either admired him, hated him, or a mix of both. He's ZELRETCH.

"I see, well then that explains your method of mysticism and–oh! Here we are!" Stopping on a platform, Kent tapped his cane on it and a door came to be in front of them which opened, revealing a large room that had two beds with one of them occupied by a blonde clad in armor and a blue dress while a translucent gold barrier covered her form.

"Saber," Shirou sighed in relief as he sank on the bed near her, thankful that she was alright.

"She's very important to you, isn't she?" Kent questioned as he looked at the two.

The redhead nodded before asking, "How did we get here? The last thing I remember was fighting Gil – I mean someone back in my…world."

Just then did the shock and the facts gotten into Shirou. He and Saber were no longer in his world.

"Before the both of you arrived here a few days ago, the tower's defenses alerted me of a rip in the fabric of space inside the tower. I got there just in time to see both of you ejected out of it before disappearing. I tried to treat your injuries but I sensed something very powerful inside you that were already treating yours so I just made you rest. She on the other hand, was losing magical energy and because of that I had this barrier made so that she wouldn't need to waste anymore of it." Kent explained before sending him a wry smile. "She's still low on it so I don't suppose you have something to help her out with that, don't you."

At those words, Shirou froze before his face went beet red as he remembered Tohsaka's very reluctant plan with the aid of a willing Sakura to give him and Saber the prana needed to help them defeat Gilgamesh and destroy the Grail. The less said about that debacle, the better.

Kent laughed loudly upon seeing his face resembling a tomato, waking up a confused Arturia as she looked at the redhead and the old man. "Shirou, what did I miss?"

Author's Notes: This X-over just kept messing me up. I can't think of updating any of my other stories while this (and a few others) kept prancing about in my mind like plot bunnies on adrenaline that I have to catch while my muse just sits there like a lazy bum. Anyway, this Shirou is a bit different than the other Shirou's from the VN and the adaptations. What the difference is you'll probably notice quite easily.

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Until the next chapter, The Undying Will.