Expanded summery: When Kariya Matou learned of the fate that Tokiomi had given Sakura over to, he went to his estranged family and begged for a chance to save her. Zouken, still a tad annoyed that Kariya had refused his heritage in his youth, agrees to allow Kariya a chance to save Sakura by winning the Holy Grail... without any real help from him save access to the library. With almost no knowledge of magic, atrophied circuits that won't be able to support a servant at anywhere close to full power for any length of time, and only a desperate wish to save someone as a catalyst, it truly seems that there's zero hope. Then, he summons a hero in red and black...

Chapter Zero

Despair.

Kariya had thought that he knew it most keenly when the love of his life, Aoi, had married Tokiomi instead of him. He had thought he knew it when his brother had declared that they were siblings no more, and as he watched his brother drown himself in alcohol in grief after the death of his wife.

Kariya had never felt despair quite so keenly though, as when he met Aoi in the park that day. She had given two daughters to her husband, Tokiomi Tosaka, both wonderful little angels with dark hair and blue eyes. The two of them had been near inseparable for as long as he had known them, and he had taken to loving Rin and Sakura almost as though they were his own. That day however, only Rin was with Aoi; Sakura was strangely absent.

At first he had thought she was merely sick or something, but when he inquired into her health, he had learned the truth. Tokiomi had given Sakura away. The man was unworthy of being the father of those two girls regardless, but to split them up was a sin he could scarcely describe. Worst of all though was who Sakura had been given to: Matou Zouken.

Aoi regretted that she wouldn't have Sakura with her everyday anymore, but even so, she supported her husband in his decisions and hoped for Sakura's happiness in her new home. She didn't know why Kariya had left his family behind and abandoned the Matou name; she didn't know why he refused to learn his family magecraft; how he ran in fear for his body, mind, and soul from the corrupt and vile things that his 'Uncle' called training.

He didn't have the heart to tell her anymore. If only he had revealed the extent of the horrors that Zouken visited upon people, maybe this wouldn't have happened. If he had gone to the Clock tower and convinced the enforcers to destroy the monster; if he hadn't been afraid of him... None of that mattered now though. He could not rewind time and correct his mistakes, only do his best to set right the consequences of his actions. All he could do now was try to save Sakura, by any means possible.

He stood in front of the door, hesitant to knock. The mansion was the same as last he had seen it, years before when he fled his home, and he knew what he would find inside. Zouken already knew he was back, alerted by his familiars or his bounded field for sure, but he would not come until Kariya swallowed his pride and knocked. It was simply the sort of person his 'Uncle' was.

Finally he rapped his fist on the door, the sound ringing in his ears in the unnatural quiet that surrounded the Matou house. He had come this far, so he wasn't going to turn back now. The door opened without a sound, inviting him into the place he had once called home. Hesitantly, he stepped in, praying Zouken would at least listen to him and give him a chance, rather than throwing him to the worms for having left.

Lights flared to life in the sitting room off to his left, and a frail sounding voice called out. "Oh, Kariya. So good of you to visit your dear old uncle. Come in, come in and have a seat. I'm curious as to what brings you here."

Fear and disgust ran through Kariya's body at the sound of Zouken's voice, but he followed the instructions, as had been ingrained into him in his childhood. The small, bald and wrinkled fiend sat on a chair with a cane in hand, looking for all the world like a harmless man on the verge of death. Kariya knew better. Amusement and carefully disguised sadistic glee radiated from the old man, sending yet more shudders through him, and setting his instincts buzzing. Tread carefully, they warned.

Even if he wanted to scream, to cry out in rage and demand Sakura to be returned safely, he knew that would only lead to his own death. Instead, he bowed respectfully and sat himself on the edge of a second chair. "Uncle," he started, marshaling his courage, "I have just learned of Sakura's adoption into our family. I am here to request that you spare her from the training of a Matou magus, and either return her to her family, or allow me to take her myself."

Zouken was silent for a beat, before barking out a laugh. "Ha! You, the child who fled from this family and refused my teachings and gifts, would ask me to give up on such fine materials? The girl is the only hope of continuing the Matou line as mages at this point. What do you have that you could possibly offer me in recompense for that, boy?"

And that was the crux of the matter, wasn't it? Even so, he had to try. "I'll come back to the family. I'll train and become a magus, just like you wanted. I'll marry whoever you want, and I'll give you a new generation of Matou magi." It was all he had to offer: his life.

Zouken's toothless smile was answer enough. "No." It wasn't enough. "You are too old to start your training with any chance of success, boy. Even as a child, when your potential was undiminished, you were not as valuable as Sakura. She comes from a strong line, with powerful circuits and and a rare element."

In other words, even his life was not payment enough to save Sakura. In that one moment, Kariya cursed his younger self for not trying to learn magecraft seriously. Even if he had run, he still had his circuits, and he still knew the basics of magecraft. He could have tried starting from scratch with what little he knew of his family's magic, coming up with a way to fight Zouken.

However, he hadn't done anything like that. Fearing magic from his Uncle's twisted examples, he had shunned it entirely for over a decade now, bordering on two. Even if he wanted to fight for Sakura, there was nothing he could do. He was at Zouken's mercy once more, as though he had never escaped.

In that moment, something threatened to die in him, to give up and simple stop trying to go on: Hope. But then, Zouken spoke again. "Hmm, yes. Well, let it never be said that I am not generous to my descendants, boy." Could it be, that he still had a chance? "There is one way you could convince me to give up on her."

Like a dying fire given fuel, Kariya's eyes brightened once more. Zouken gave a dry and raspy laugh before continuing. "Indeed, boy, you might remember what is about to return to Fuyuki. No? Well, no mater; the Holy Grail War is coming up again, and I have no one to enter it for me. Smart lad that you are, I'm sure you can see where this is going?"

The Holy Grail War. A battle royal between seven magi and their seven summoned Servants, a battle of Heroes of old for the sake of a Wish. The chances of survival in such a thing were slim at best, and the chances of winning for one such as him were nearly non-existent, even with help. However, even if the chances were slim, he'd take them.

Zouken cut him off before he could say anything, reading him without effort. "Good, good. You still have some of that old determination and fire that let you go against me in your youth. Then here are the terms: You retrieve the Grail for me, and in exchange, Sakura will be yours to do with as you please.

"With the Grail, I'll achieve perfect immortality, and mastery over the third magic while I'm at it, perhaps. Thus, I'll have no need for descendants or untrained children to be turned into my tools." Zouken stood up, and started walking towards the stairs leading up. "I'll even provide you the means to prepare. You'll have access to the old house and my library for the time leading up to the war. Don't expect me to help with the catalyst or your training though. You gave up the right to such things years ago."

Honestly, it was more than he could expect, yet still no where near what he needed. Even so, Matou Kariya swore to himself that he would do everything in his power to lessen the burden on Sakura, and to save her from her cruel fate. With that oath in mind, he followed the horror he called 'Uncle' up to the family library to begin his studies anew.

Matou Zouken walked down to his workshop, his spirits higher than he had expected. Truly, fate was favoring him, gifting him with such things one after another. He did not expect Kariya to win, or even to provide more than a token resistance to the other masters in the war, but if he played things right, it would hardly matter.

At the worst, Kariya would have his spirit crushed completely in his struggle, providing Zouken some much needed amusement as he watched on. He could slowly break the boy with his every failure until the boy didn't even think before crawling to him, begging for help. A dry chuckle echoed off the stone walls of the crypt beneath the Matou home. Such a sight it would be, and his suffering, all for that girl's sake, would help to break her psyche for him so much quicker.

On the other hand, if he somehow came close to winning, Zouken could easily steal his servant from him, sacrifice him as a pawn to finish off his last enemies, and then claim the grail himself from the shadows. Depending on what sort of servant was summoned, Kariya might even be able to win, actually handing him the grail himself. What delicious humor that would be, to see one who hated him so grant him the means to reach immortality.

What a fool he had raised.

"Now struggle and squirm for me, boy. Wallow in despair, wade through sin, and writhe under grief and self-recrimination. Fight til your last desperate gasp of air for me, boy, and finally serve a useful purpose. Gyeh-heh-heh-heh."

The sound of a swarm of insects scurrying across stone and buzzing through the air at once filled the room, blending into the man's laughter until they were one and the same.