Fate/False Faker, a Stay Night story.

[Chapter Three] Disruption of Continuity

Sitting on a roof near the School from the night before, Drake raised his hand and let blood drip into a 50. Bmg bullet casing. Like Kiritsugu's Origin Bullets, Drake had to give up a part of himself to craft powerful ammunition he called Dark Matter Rounds. The bullets explode and annihilate organic, phantasmal, and spiritual matter on contact, but only activate when flooded with mana which turns his blood in a volatile crystalline form.

Drake concluded that they would be necessary for killing Zouken and Shinji Matou. Those were side projects, however. His main goal was finding Rider's Master.

Simple deduction and context from the night before told him that Sakura Matou was close with Shirou Emiya as well as being Rider's Master. Drake wondered if Zouken was senile, letting a nothing like Shinji command a Heroic Spirit.

The school bell rang as Drake finished assembling his sniper, the Longsword.

He took aim, watching the students enter the school as part of their usual routine. He eventually spotted Shirou, Rin, and Sakura in three different places.

Drake: Ooh, who's that honey with the brown hair?

...He also noticed their teacher, Taiga. He quickly regained his focus and collected his thoughts.

Drake: Okay, my theory was right. Sakura Matou is the Master of Rider. I wonder what's her magic like?

Drake increased the zoom on his scope and poured some mana into the special lens which gained an x-ray effect for quick kill shots. He witnessed something that made his skin crawl.

Drake: What the hell...Zouken, you twisted piece of shit.

Crest Worms, small ones all throughout her body and a larger one wrapped around her heart. Eggs in places he won't look.

Drake had seen some vile shit in his time as a mage, but even though he was trained as an assassin from a young age, he wanted to throw up so badly.

Then at that moment, all of his surroundings just felt...wrong. A presence behind him sent chills up his spine. In one swift movement, Drake let go of his rifle and drew his pistol as he spun to point it at what was behind him.

A silent creature floated just a few meters away. It was cloaked in black ribbons and made no movements towards or away from him. It just watched him for a moment before vanishing from his sight as he blinked.

Drake let out the breath he didn't know he was holding.

Drake: What was that thing? It didn't feel spectral or phantasmal, just...off. I'll settle it later. For now, I need to find a way to deal with the worms and Zouken without hurting the girl.

As Drake began to disassemble his rifle, Assassin spoke through their mental connection.

Assassin: Contractor, I have found something that would be to thy liking.

Drake: Oh?

<Location: Forest] <Time: Sunset] <While Shirou and Rin learn about Kuzuki from Issei]

Drake: To think some idiot mage would leave something as valuable as this unused.

Standing beside his Servant, Drake looked at an untouched summon circle. It was just left in the forest inside of an old abandoned shack. Drake assumed it was left over from the fourth Heaven's Feel, belonging to a potential master caught off guard by the Assassin or another Master.

Assassin: Contractor, a warning.

Drake: Hm?

Assassin: The parameters of this Grail War art...incorrect. The summonings for the Archer and Assassin classes are faulty. As such, Tis possible to summon several Archers, Assassins, or an Extra. Hearken, the Will of Thine World shall take notice.