Chapter 1: Fateful Night's Twist

Hey, do you know about the multiverse theory? It should be common knowledge now, but physicists have determined the existence of parallel worlds, an infinite number of worlds so like one another and yet not. The multiverse is a set of worlds that hold every possibility and every reality.

Say, for example, in the Fourth Holy Grail War of Fuyuki City, if a certain deranged serial killer had stumbled upon a different family one night, how differently would things play out?

Not much, you say? The serial killer would still summon a Servant and it would still murder the child? Well, that's not impossible. Sure, the child could just die and the war would play out like it did in countless other iterations.

But what if the summoned Servant wouldn't kill the child? After all, what kind of Servant would kill its own Master on the get-go?

It all began with that one fateful night...

The ? family residence was attacked one night. The parents were caught off guard and restrained. Their only son hidden in the upstairs bedroom heard the commotion. His parent's muffled scream and a stranger's maniacal laughter. The boy searched for a weapon he could use. He fished out his baseball bat and climbed down the stairs, quiet as a rat. He snaked behind the attacker. The boy struck the metal bat at the man's head.

The man ducked and tripped the boy with the back of his foot. He faced the boy with a disapproving gaze. "Hey, hey, kid, that hurts like hell when it actually hits. And I should know, in the past, some kids got the jump on me. Ugh, that was really embarrassing."

He snatched the bat from the child. "Can you imagine a brat beating the big old bad serial killer? He'd be a hero, right? Cool, right?" A grin spread on his face. "Too bad, kid."

The boy saw his metal bat swing down to his face and then everything faded to black.

The boy opened his eyes in hell. It was the smell that got to him first. The metallic stench violated his nostrils, inflaming him with dread. His eyes finally adjusted to the dark and horror struck his face pale.

The lights to the living room were turned off. The furniture forced out to the sides. At the center of the room, a bloody magic circle had been drawn. Horrible crimson ran across the wooden floor, staining everything in death. He tried to scream, but found his mouth gagged.

"Oh, you're finally awake!" A familiar voice rang in the dark. His eyes caught the sick grin of the man from before, the self-declared "serial killer".

"Perfect timing." He clapped his hands. He walked to the couch at the edge of the room. "Your parents were beginning to lose too much and I was getting bored."

The boy's eyes widened in horror. There sitting on the couch, his parents bound and bloody, suffering several deep stabs in the gut, their skin marred with long cuts, their mouths gagged like his, tears streaking down their sweaty faces. From their wide open wounds, their blood leaked out so naturally that in the dark they looked like black sweat. One drop out after the other, a constant flow.

"Here's how the game works, kid." The man smiled serenely. "I need a lot of blood for a project of mine. That's why I'm having your parents here help me out a bit. But it seems I bit off more than I could chew..."

His wolfish grin gleamed in the dark. He placed his hands on the parents' shoulders."You get to pick which parent gets to live! Isn't that COOL?"

What?

The boy furrowed his brows in despair. How was that in anyway cool? Terror cried out through his mother and father's eyes. The boy focused on them, paralyzed in that same terror. The weight of his decision crushed him. To save one life, but lose the other?

"Oh, don't give me that look." The serial killer frowned. "I rarely do these kind of things, you know? They're kind of a drag on my part." He scratched his head wildly. "But I couldn't help myself this time. I mean," he grinned like crazy, "you tried to play the hero, right?"

The boy's trembling eyes stilled. What?

"You wanted to be the COOL hero of this story! It was just so cute!" The man's breathing went manic. He hugged his stomach. Giggles broke out from his mouth. "A kid imitating a superhero, to save his precious family no less!"

The man halted. His eyes stared dead ahead. "It makes me want to smash that kid's dream."

The boy's eyes freaked out. Tears streamed down his face. He couldn't decide. His mother or his father... only one could be saved, one must be sacrificed.

"Huh? What are you waiting for, kid? Pick already." The man pulled out a bloodied knife. "Greedy kids need to be punished, okay? You only get to keep one parent, alright? Just one. So, who the FUCK is it going to be?"

The man stepped behind the couch. His face still smiling disconcertingly.

"Is it going to be DADDY?" The knife dug into the boy's father's shoulder. The blade twisted and stirring his father's innards, producing the gruesome sounds of tearing flesh. "Or is it going to be MOMMY?" A merciless stab into his mother's shoulder. Her blood erupted out like a blossoming crimson flower.

The boy screamed into his gag. His heart wrenched, but he still couldn't pick. He loved them both too much. He looked them each in the eye, his mind spiraling into despair.

His parents' expressions now warped in pain looked back at him. Their mouths gagged. They could share no words. Their restraints allowed only their fingers any degree of free motion. A single gesture. A flex of a finger and someone's life would be offered up. They all came to the same decision.

"What the hell...?"

All three of them pointed at themselves at the exact same moment. The parents told their son to sacrifice themselves for their son and spouse. The son unable to choose between his parents offered himself instead.

The serial killer's head sunk low. His expression struck dumb, covered by a sinister shadow.

"What's up with that... That's so not COOL... You're all so boring," the man whispered. "You would all die for your family? What kind of ending is that? Too boring. That's NOT COOL at all!"

The man who kept saying COOL like it was the holiest word in the world stood silent. Without another word, he slit the father and mother's throats with a single swift motion. Their carotid arteries burst forth instantly, spouting out the last of their lives.

The boy screamed his heart out so hard his vision blurred.

"You chose wrong, hero." He heard last.

At some point, the boy woke back up. He lost track of the serial killer's actions. The man was still in the room. His parents laid crumpled on their now stained sofa. The man had wrung them dry for every drop of blood they had to offer. It had been a heart-wrenching sight, but now, the boy could no longer see pass the tears in his eyes. Not even caring to look anymore.

His pupils were obscured with the dark. He replayed his parents' final moments over and over in his mind. That last look of sheer terror they shared haunted him. If the boy had done things differently, if he had somehow made a different decision, would they still be with him in this world right now? If perhaps he had called the police instead of trying to play the hero... then this tragedy might never have happened...

The man's heartfelt laugh broke the boy from his thoughts. The man had almost finished the magic circle of blood on the floor. He grinned as he smeared more of the boy's parents' blood for extra measure. Just a few more touches here and there and... voila! Finished.

"This is gonna be so COOL!" The serial killer breathed out ecstatically. He clapped his hands together and looked at the boy. "Hey, kid have you ever heard of summoning a demon?"

The boy was lost in a daze and didn't bother to reply.

"That's right, a demon. Like in video games and anime! A real flesh and blood demon! Wouldn't that be just the COOLEST!" The man opened his arms in a wide embrace. "Just think of all the COOL things I could do together with a demon! I don't even know where to begin!"

"Oh," the man paused and looked down at the boy. "Of course, I'll start with feeding you to it."

The boy did not so much as flinch at those words. His consciousness already retreating from reality, escaping into an inner world where everything was right and obeyed his will.

The serial killer started his summoning, reciting lines from an old leather-bound book. The words didn't mean anything to either of their ears. The man mouthed each word poorly.

A demon. The boy didn't know what actual demons looked like. But staring at the man who killed his parents stand beside a circle made from their blood, it filled with him a single thought.

That demon, right over there, ought to die. He needs to die, in the most painful possible way.

The boy would give anything and everything if it should mean that monster's destruction. He didn't care about justice or heroics. He just wanted him to suffer in the worst possible way.

"Fill, fill, fill, fill, fill," The man chanted. "Yeah, that makes five times..."

So consumed was the boy in his dark thoughts, that he didn't even notice the searing hot pain in his left hand.

The bloody circle sparked red electricity and the boy's hand shone a brilliant red light.

"Wha-" The man shielded his eyes from a sudden flash of light.

The dark room was illuminated. A burst of air came from the center of the circle of blood. Smoke filled the room and a new third silhouette appeared. It was the broad figure of a man in his early thirties.

The smoke soon parted and the serial killer stared mouth agape at his newly summoned demon.

For a demon, he looked perfectly human. Rather tall, muscular, tan skinned and with sleeked back white hair. He wore dark tight fitting body armor shrouded by red garments.

The demon frowned. "Are you supposed to be my Master?" Its nose twitched. The familiar stench of blood immediately registered.

"Eh, Master?" The man blinked twice, thrice, then tilted his head. He shrugged. "Maybe, but, ugh, for the time being, how about a sacrifice, Mr. Demon?" He gestured to the boy tied up on the floor.

The demon raised a brow, but then widened his eyes after having one look at the boy. He gritted his teeth. So, that's how he had been summoned.

Kill the monster. Kill him. Kill him.

The connection was flimsy, but sturdy enough for the boy's thoughts to reach him.

"I see how it is." The demon sighed and shook his head. "No matter the time and place, my summoning always means the same thing."

"Huh?" The man didn't understand the demon's words. But he didn't have the time to even process it before he felt a piercing sensation go through his abdomen. He stared blankly at the new red fluid bursting forth from his stomach and seeping into his clothes.

"W-what's this coming out of me...? It's... so COOL..." His smile broadened at the new found color of his own blood. Joy filled him as warmth left him.

"As you wish, Master," the demon spoke in front of the man. "This monster will suffer your rage."

The living room of the ? household was filled with the ecstatic screams of a man experiencing the worst of human suffering physically possible. The demon fulfilled his contract with his master without a smile. The boy sprawled on the floor almost giggled at the sight of the killer's end.

Who was COOL now?

The serial killer's screams had been brief. A sword lodged itself through his throat after the first few seconds of his torture. After a good half hour of unspeakable cruelty, the serial killer was just another bloodstain on the floor. The demon freed the boy from his restraints. He cut the boy's bonds loose with the same knife that had ended his parents' lives.

The boy now free simply sat on the bloodied floor. His eyes never left the lifeless corpses of his parents. Their heads fallen to the floor, while their bodies remained seated on the couch. The killer had taken some sick delight in beheading them after they already died of blood loss.

"Servant Caster at your service, Master," the 'demon' introduced himself to the boy.

The boy stared up at 'Caster' and familial recognition sneaked into his heart. "Dad?"

Caster's frown sank even lower at that. He shook his head and did the boy a kindness by snuffing out any false sense of hope. "I am not your father, boy. I am your servant and you are my master. That is all."

The boy just blinked at Caster's strangely cold words. "I am your Master...?"

"That's right." Caster nodded grimly. "And you've just stumbled into a war ten years too early for you, boy."

The servant stepped towards his master. His hands tightened around the weight he carried. "I'll be frank and be the first to admit that you and I have the lowest chances of surviving the first night, let alone winning the whole war."

Caster glared at the boy's confusion. "So, I will do us both a kindness and put an end to things right here and now." He raised his hand and the boy shrunk away from the knife that slayed his parents, now in Caster's hand.

"Are you going to kill me...?" The boy asked slowly.

"Yes."

"I see..."

Caster tightened his expression. "You're not afraid?"

"I am." The boy shook his head. Still, his face remained stoic. "I don't want to die. But, I don't think I have the right to live either..."

Caster's raised arm didn't move. On a whim, he asked, "Why do you say that?"

"Because it's my fault that monster killed mom and dad. I was the one who wanted to play the hero and save them both." He explained, tears running down his face. "I thought I could do the impossible if I just tried hard enough... but in the end, I only made things worse..."

He bent his head down, too ashamed to look at his Servant in the face. Tears and snot smeared his cheeks. "I don't deserve to live!"

Caster's frown twitched at the boy's words. Their connection as Master and Servant only further conveyed the boy's heartfelt regret.

Caster could practically feel it himself. The heavy weight of having cost the lives of those dear to him. The gut-wrenching regret of having committed a mistake in judgement for the sake of a misguided heroism. The saddest wish to put an end to one's own life.

Caster saw himself, standing atop that hill of swords, his back stabbed through with the countless blades he made himself, staring up at the disjointed sky. Always waiting on that hill, understanding that he would never be understood.

He looked back down at the sniveling child on the floor.

Caster dropped the knife. Its blade lodged into the floor with an audible thud. The boy shrunk back away from it, still waiting for the inevitable.

But instead of the cold stab of steel he had expected, the boy felt a brush of warmth embrace him.

"Huh?"

He halted at a loss. His rapid breathing returned to normal. His tears froze in place.

Because after all, Caster was holding him in his arms. Their hearts pressed against each other so close, his pain became Caster's pain.

"Caster...?"

The Servant did not answer. His resolution for the coming war hardened.

"What is your name, Master?" Caster asked even though he already knew.

"Eh, uh, it's Shirou..."

And so, the last Master and Servant pair of the Holy Grail War came to be that night.

Author's Note:

The cover image is some great work that features what EMIYA would look like as a Caster. It was made by SUEUN and uploaded on their Twitter account. I didn't exactly ask for permission since I don't know any Korean, but please credit the original creator.

Thank you for reading.