"Let silver and steel be the essence." Matou Kariya chanted, kneeling in front of the Summoning Circle, where a piece of the Round Table laid.
Behind him, the monstrosity that calls itself Matou Zouken stood, or rather took its human form as a sadistic old man.
"Let stone and the Archduke of contracts be the foundation." The path to becoming a mage was heartless and disgusting. The years spent devoured alive by the Crest Worms have left Kariya's hair white and much of his body paralyzed.
"Let red be the color I pay tribute to." But it was all worth it. All worth it to rescue Sakura from this monster, and all to get back at Tokiomi for abandoning his family.
"Let rise a wall against the wind that shall fall." But what guarantee was there that Zouken would give up Sakura even after getting the grail? Kariya couldn't bank on such a gamble alone.
"Let the four cardinal gates close." But the training, while horrendous, provided Kariya with useful knowledge. Especially about Zouken, about the knowledge that the creature wanted hidden.
"Let the three-forked road from the crown reaching unto the Kingdom rotate." With his decision solidified, he pulled out a Crest Worm from his jacket's pocket.
"Let it be filled. Again. Again. Again. Again." He could tell that Zouken was looking at him in surprise. While it was aware of the worm, he had no way of knowing why Kariya had it.
"Let it be filled fivefold for every turn, simply breaking asunder with every filling." And right as the Circle reached its brightest light, Kariya threw the worm into the circle.
"What are you doing?!" Zouken snarled as the worm in the circle shook from the mana going into it. "That will sabotage the summoning-" it suddenly stopped when a loud sound pierced the chamber. A loud sound that for some reason brought fear him.
That sound was Kariya's laughter, not heard for many years.
"This training was hell," Kariya said, forcing his face into a smile. "But I learned two things from you. The first was that I learned of the clan's founder, it's true founder Makiri Zolgen."
"No…"
"And the second was a little thing known as the Second Magic. The mortals you Magi look down on, they call it the multiverse theory. Can you already guess whom I'm summoning?"
"You rebellious-" but whatever the swarm was about to shout when the room was filled with a bright sacred light before it vanished just as quickly.
Standing next to the table fragment was a European with spiky blue-hair wearing a black trench coat over a brown suit, with a medallion tied around his neck with a blue ribbon. His piercing red eyes fell onto Kariya while holding the docile Crest Worm used to summon him.
"I am the servant Caster," the Servant said, in surprisingly perfect Japanese. "I ask you this, are you my master?
"That's right," Kariya replied courtesy. "It's good to finally meet you, Makiri Zolgen."
"What have you done?" Zouken questioned furiously, raising its cane in the air in rage as its body shook and began breaking apart.
"I was surprised to learn you of all people sought love and peace in your past," Kariya boasted. "I figured that if there's a version that ended up as you, they'll be another that would die a good man."
"So this is supposed to me," Caster questioned, his face scrunched up in disgust. "It looks like death was preferable."
"Do not talk back to-" Zouken suddenly paused when its body came to a halt, unable to take a step forward. It tried to break apart to its swarm form but remained imprisoned in its human disguise.
"Ah, now I see," Caster mused, raising his hand to the abomination as his Magic Crest glowed. "A soul that survived by merging with the Crest Worm hive. But humans were never meant to live as long as you have."
"You, you can't do this," Zouken snarled. "I need the Grail… I need it to become immortal."
"Really? Then tell me, why do you want to become immortal."
Zouken remained silent, but not because Caster commanded it to. It was silent because it had no answer. Centuries of constant rebirth had made it lose its old memories, its old beliefs.
"I- I forgot."
"You, you forgot?" Kariya parroted in disbelief, before turning to rage. "You put Sakura and so many others through hell, and you don't have a reason why?!"
Caster merely scoffed."How pathetic you are, creature. I'll be doing the world a great service," a wicked smirk crossed his expression. "By ripping your soul apart."
"NOOO!" What was heard was a demonic roar as Zouken's body broke apart, splitting into numerous Crest Worms that spewed out fluid as they dried up to mere husk. The roar echoed through the hall for a few seconds before the hall returned to silence.
"W-what did you do?" Kariya asked, still terrified by what might as well be an exorcism.
"I expelled that shattered soul out of the hive. It will now spend its remaining moments in the depths of hell, where it belongs."
"... is that so," Kariya said, before nodding. "Thank you, but I have one more thing I asked you."
Hours later, Kariya, the new head of the Matou family, knelt above the black-haired girl. Thanks to Caster, the Crest Worms inside her were forced out without killing her in the process, restoring her natural complexion. But the mental trauma she forced to undergo was still present. Thankfully, Kariya will be there to help her recover.
He checked her temperature with his hand, letting him see the trio of Command Seals on the back. He did not expect Caster to be so willing to aid them, not even requiring an overwhelming order. He even healed the damage Kariya undergo, and granted full control of his own swarm.
"So this was the fate of the Zolgen clan in this world," he Caster comment coldly from behind him. "Banished from Russia, left a dying branch under the tyranny of a descriptive beast, forcing its will upon the innocent."
"Again, thank you, Caster," Kariya said. "I never thought I'd be indebted to Zouken of all… things."
"You aren't, and you never will be."
"Hmm, in any case, Sakura's safe. No one can hurt her now," he gently stroke her black locks.
Zolgen raised a curious eyebrow. "What about you, Master?"
"What are you talking about?"
"Zouken might be destroyed, but your rage is not yet quelled."
Kariya pulled his hand away from Sakura, not wanting her to sense his anger. "Zouken might have put her through hell, but he wasn't the one that put her in there, her-" he swallowed his throat. Father is a term that bastard doesn't deserve. "Sperm Donor left her here, abandoned her and took her name Tohsaka away."
"More that one child?" Caster ventured. At Kariya's expression, he continued. "I was a Magus, remember? I know that the Family Crest can only be passed to one. You said she was a Tohsaka. A renowned family, even for a bunch of Orients, no offense, would be the target of many mages. Only giving her to a mage family would be her best chance."
Kariya frowned. Of course, Zolgen wouldn't be different from the rest of the Magi bastards...
"But her father must be a complete fool."
That snapped Kariya out of his musing. "Excuse me?"
"How could Sakura possibly prosper here? The Matou's are a dying line, what could they offer. He could have given her to the Edelfeldt, they would be willing to train her while maintaining some humanity. Instead, he handed her over to these worms."
"Ex-exactly!" Kariya rose to his feet. "I can't let Tokiomi get away with this! He needs to pay for what he did to Sakura! He has to be stopped before he hurts Aoi and corrupts Rin!" he suddenly frowned. "But against his servant..."
"Yes, we're at a disadvantage. Not only am I a Caster, one of the weaker classes, but I am a relatively modern magus against heroes centuries and even millennium older. We would lose in a direct flight.
"But that doesn't mean we don't have a chance," Zolgen mused. "The Grail provided me with enough information about the setting of Fuyuki. We can plan our fight and defeat the other masters. We can terminate Tohsaka Tokiomi for you."
"And you would get your wish then?" Kariya questioned.
"The chance to use the grail to turn this world into a utopia. One where Magi won't sacrifice their humanity for abstract goals." He held out his hand. "Are you with me, master?"
Kariya was silent before grabbing the stretched hand and shaking it. "Count me in, Caster."
'I'm glad to hear that,' Makiri Zolgen thought, hiding his smirk. 'I do plan to make those promises true. After all, I will reach my utopia, no matter the cost…'
Yeah, think of this as a spin off of my Boy King story. I got the idea after reading about Zouken's bio, about how he dreamed of creating a utopia free of suffering, long before his soul rotted away to the monstrosity we see today. But there is a lot of difference. While Ko-Gil is a good-hearted kid, Zolgen is a manipulative bastard, an anti-hero like Gilles and Medea. Think of Light Yagami. But he has Kariya's support at the moment thanks to killing Zouken, healing Sakura, and promising justice against Tokiomi. Though the words "at the moment" are important. Kariya will have to stop Zolgen in the future.
Anyway, take this story as a challenge, you willing crazy writers.