I do not own anything except my own ideas. Wish I could make those canon.

4 - Demon Lord VS Incarnation of Yin

Time: One Week until the start of the Holy Grail War

Music: Lord Ghirahim Battle 2

Illya had backed up to the blocked gate as she stared in amazement at the two Servants fighting each other. Assassin had cast of his cape and his arms and part of his face were covered in a odd black substance. His face had lost that teasing look and was now focused on Berserker. Berserker, however, had a wild look in her eyes and was grinning like a maniac. Illya guessed that she probably enjoyed battle a little too much.

The battle was going nowhere. Berserker's sword was blocked either by Assassin's arms or sword, and he would teleport out of danger if he needed to. Assassin would manage to hit Berserker, but she had some sort of healing factor.

Assassin jumped back from a recent exchange of blows, and tched. "You have absolutely no skill, yet your pure strength makes up for it. What sort of swordsman would actually be like that?" He asked in slight annoyance and astonishment.

Berserker returned to her base stance, standing slightly sideways with the tip of her sword pointing to the ground to her left. The handle was to the right of her face, having her mouth covered by the blade. "I do not take pride in my sword. I never have and probably never will. My sword is only a means of destruction." As she was talking, the four symbols on her sword began to glow. "Even if I wanted to know the ways of the sword, it would not be possible because I will never get a true teacher."

"And yet, you call your weapon yours." Assassin pointed out. "That is," He licked his lips with his terrifyingly long tongue. Illya shuddered. "Quite intriguing."

"Stop scaring my Imouto!" Berserker yelled as she swung her sword. "EXITIUM!" The dark red light of the attack blasted forward at Assassin. He grinned and teleported out of the way. However, Berserker launched another sword beam ("EXITIUM!") at a random spot where Assassin appeared. His eyes widened, then he put his arms in front of him. The beam slammed into his arms, throwing Assassin back with a cry. He hit one of the barriers that he had put up and stayed there for a few seconds before falling back down to the ground face first. Unfortunately for the people who wanted to see Assassin faceplant, he teleported right before he hit the ground and appeared again perfectly fine if nothing had happened. However, he looked disturbed at what Berserker had just done.

"How did you know where I was going to be?" Assassin asked. Berserker stood with her blade to her side, stabbed into the ground.

"You're predictable. You always gesture when and where you are going to teleport." She said.

Assassin's eyes widened. "I trained to make myself as unpredictable as possible!"

Berserker ripped EXITIUM from the ground and pointed it at Assassin. "Exactly, you trained. And when you train, you begin to use patterns. That is why those who have near to no training and surprising talent are so unpredictable." She set the sword on her shoulder, somehow having the sword not cutting into her skin. "I taught myself how to read people's battling style and the weaknesses of different styles. Your style relies on freaking out the opponent and being unpredictable." She shifted into her base stance. "I wonder, how would you fare against someone using the same style?" And with that, Berserker disappeared in a flurry of two-dimensional diamonds.

Assassin's eyes widened even more, then he ducked underneath a swing from Berserker's sword. He twisted to slash Berserker, but she had already teleported. Then, Assassin teleported. Berserker appeared swinging her sword, then blinked as she saw that Assassin was not there. Her eyes widened as she jumped away from the knifes that Assassin shot at her from somewhere. He then appeared, a scowl on his face.

"You are not someone to be trifled with." Assassin said, with black and white diamonds forming around him. "You, somehow, were able to copy my abilities, which were a gift from my original master." He spread his hands out, more diamonds forming. "Now, you will face my true power!" There was an explosion of power, a geyser of black and white diamonds exploding from underneath the Demon Lord. "Body of Sword!" Assassin yelled, his voice slightly muffled by the flurry of diamonds. When the diamonds finally petered out, a new Assassin stood before them.

His skin was now a reflective black that gleamed in the moonlight. He also had odd white diamond designs over his skin, all leading to a diamond right on his chest that screamed weak point. His eyes were now pure white, and his hair looked somewhat like a tip of ice cream. It was a terrifying image.

Assassin laughed. "You see! This is the true power of my original master! This power makes me invincible!"

"And yet, you still lost to Link." Berserker said, back in her base stance. "You still failed to defeat the only person who would defeat your master Demise."

Assassin twitched. "Shut up…"

"And, In the end, Demise took from you the source of your power, which was his sword, and killed you by doing so." Berserker continued.

Assassin twitched again. "Shut up."

"I cannot believe that after death you would still be so loyal to the demon that killed you." She finished, oblivious to Assassin's growing rage.

"SHUT UP!" Assassin yelled as he charged towards Berserker. He had summoned a huge sword that was nearly as big as EXITIUM, but not large enough. The two blades crashed against each other, sparks flying. Then, Assassin's huge blade exploded with a blast of darkness, knocking Berserker back. Assassin roared as he charged towards Berserker, two of the blades in his hand.

Berserker then did something that made Illya's brain hurt even more. She cried out "Dodge Roll!" and dived at Assassin. She slipped between his blades and rolled behind him. She then turned around and slashed at Assassin's back. The sword didn't cut him, but it sent him flying. He once more hit the barrier that he had set up. Only this time, when he fell, he did land on his face.

Assassin slowly picked himself up and growled. "You… Will pay!" He charged again, another blade in his hand. Berserker smirked and sidestepped his attack. She then launched another beam slash at Assassin, sending him back to the wall. Assassin laid there for a few moments, then struggled to get up.

"EXITIUM's edge causes catastrophe to all those who are touched by it. It does not matter if you have an impenetrable defence, it just harms the opponent as it would when cut by it. You have no hope. However, I do have one last question." Berserker said, slowly raising her blade skyward.

"W-what?" Assassin sputtered out, confusion written across his slightly metallic features.

"Die." Berserker stated. The then went to bring her now glowing sword down. "EXITI-"

A foot encased in dark energy shot out from the sky, hitting Berserker right in the chest. She gasped in pain as the figure kicked off of her and landed a few inches away. The figure then reached back his right fist, as if for a punch. There was a gleam of golden light, before it was enveloped in the same dark energy that covered his foot earlier. With a cry, the figure then punched Berserker, sending her flying into the blocked gate, sword still in her hand.

Illya rushed over to where Berserker lay, slumped against the energy blocking the gate. "Onee-Chan!" She yelled in horror as she saw blood dripping from her older sister figure. Berserker looked up with a look of horror. "No… You can't be Caster."

"You let your emotions run wild, Assassin." The revealed Caster said to Assassin, ignoring the two females. "That was clearly a taunt for you to get angry. You must have the power to resist such words."

"Of course, Master." Assassin said, getting on one knee and bowing to Caster like a knight.

"Imouto, on the count of three, we are getting out of here." Berserker said, having sheathed her blade and was undoing some of the wrapping on her palm.

"What?" Illya asked.

"THREE!" Berserker shouted, slamming her palm into the blocked gate. There was an odd noise similar to that of a vacuum, but more ominous. The diamonds that made up the barrier were sucked into Berserker's palm. She then grabbed Illya and jumped out of the shrine. Illya stared at the retreating figures of the two Servants. "Onee-chan, who was Caster?" She asked as they continued to leap from building to building.

"The strongest person who can use magic, and blessed by the gods with a source of unlimited strength. He is the result of a curse placed on one man, constantly appearing to destroy a kingdom. He is able to withstand a sword stabbing him in the heart, that grows more powerful the more sins you make no less, with pure power of will alone. He is able to raise the dead and curse different lands so that the worst thing that could happen does. That was the King of Evil, Ganondorf." Berserker said, her face completely serious. "That is one person I do not want to fight unless I have some sort of back-up. Namely, Saber with her Excalablasts."

Illya had learned a few things about Saber from Berserker during the two month wait for the Holy Grail War to start. Apparently, Saber was actually the real King Arthur instead of a copy like most of the other Servants, and couldn't go into a spirit form because of that. When Illya had asked if there was any connection between Saber's and Berserker's inability to go into spirit form, Berserker said that she was not sure if she was actually dead or not and that she was very confused on the matter because she remembered having her heart ripped out of her chest. Illya found the image of that disturbing, but found it even more disturbing when Berserker ripped her heart out of her chest to check if it would actually kill her. After that, Illya made sure to try and not bring up Berserker's death.

"Right now, we're heading back to base." Berserker continued, bringing Illya out of her musings. "We need to figure out a plan to deal with these new variables, and to plan for upcoming variables. This is somehow going to be a mass Crossover of sorts, so we need to plan for the worst."

Illya just nodded. She had goten used to Berserker saying odd things like AU, Crossover, and Canon. She had figured out that Canon ment something that was original, something that was copyrighted. But she didn't know what AU or Crossover ment yet. Or why she said the things about her everyday life.

"Anyway, where is the castle?" Berserker asked innocently. Illya blinked and looked around, only to see nothing recognizable.

"We're lost, aren't we." Illya said, accepting her fate.

"Yep." Berserker said, also accepting her fate.


Later - 12:27 AM

"Finally!" Berserker and Illya shouted, having found the the Einzbern Castle. They had been going around town to try and figure out where they were for the past few hours. Eventually, they had to ask for directions from a local. Well, Berserker did. Then the guy groped her. After dumping the unconscious form of the guy into an alley, they went to a new person. This time it was a girl. Who also groped Berserker. They stopped asking for directions and tried to find it on there own. Berserker started to complain about mages and their unwillingness to use technology. When Illya probed about that, she got a rant about the uses of modern and future technology as well as "Merlen always used some sort of tech with his magic for crazy bullcrap." Illya was sure that Berserker didn't mean the Merlen, but probably someone else named after the magician.

Eventually, they had found the forest that the Einzbern Castle was in, but then they had to search the forest for the castle. That took about another hour trying to find the road that led to the castle, and they accidently followed it out of the forest, then went the other way to the castle. Needless to say, it was something that both Illya and Berserker did not want a repeat of.

"We are getting phones at the first opportunity, and then teaching your maids and you how to use them effectively." Berserker said, clearly irritated. However, Illya agreed with the statement. After Berserker's 'teachings', She now understood how useful technology was. Really, it was a wonder that no other magus had used technology that much yet. The only person who had was her father.

And he killed many people doing it.

His usage of modern weaponry and the tendency for magus to underestimate him was a deadly combination. She still was surprised that no one had taken his mantle of being the "Mage Killer". Surely someone would have realized that technology was useful, not something to be avoided by the plague.

"Imouto?" Berserker asked, snapping Illya out of her thoughts.

"Wha-? Oh! What is it, Onee-chan?" Illya said, mentally slapping herself for ignoring Berserker. She was such a fount of knowledge, and let things slip that could be very informative.

"You were spacing out there. I was just asking what show you wanted to watch." Berserker said. Illya thought about it. Sure, it was late, but they had to watch something before they went to sleep. Besides, she needed to take her mind of Assassin and his tongue. But how? She could watch some sort of Magical Girl anime to forget about his creepiness or…

Illya's perverted grin and light blush lit up the area around the Master and Servant. "Ecchi."

Berserker's face gained a similar grin, but did not have any sort of blush. "Ecchi it is." And with that, the two perverts walked into the house.

The night was peaceful for fifteen more minuts, then a skreem peairced through the air

"W-what is this!"

"Sella, relax!"

"H-how can I relax when th-Ah! Leysritt!"

"What."

"W-why are you do-Ah! S-stop!"

"Wh-Ah."

"This is fun!"

"Party!"

"WHY!"

Author's Notes-

Well, that was fun to write. Surprising how you dread a scene at first, then it becomes more enjoyable as you continue to write. Anyway, the identity of Caster has been revealed! Cannot wait to see your reactions! And it seems that the only Servant that fits her class so far is Saber. Not sure if I want to replace Lancer yet. Anyway, here are Berserker's Stats:

Servant Class- Berserker

True Name- ?

Additional Titles- Incarnation of Yin

Master- Illyasviel von Einzbern

Gender- Girl/?

Alignment- True Neutral

Birthday- ?

Place of Birth- ?

Age- ?

Likes- Cute things, ?

Dislikes- ?

Talents- Killing Thing, ?

Strength- EX

Endurance- EX

Agility- EX

Mana- EX

Luck- EX

Noble Phantasms- EX

Class Skills-

Madness Enhancement: X (D)*

* When true Noble Phantasm is in play

Personal Skills-

Territory Thievery: C+ - A skill for those who were able in life to take the territory of others and make it their own.

Berserker can only take the territory of those she is allied with, and only for her personal needs.

Memories of Another Age: EX- A skill that allows the Servant to know who anyone is just by seeing them, depending on it's rank

Berserker can see anyone and know who they are and what they are planning due to her knowing the "Truth".

Battle Continuation: EX

Berserker can battle for as long as she wants and not sucume to any wounds in or after battle.

Noble Phantasms-

EXITIUM- The Edge of Ruin: A+(Anti-Unit) - Berserker's sword. It can only be unleashed when swearing to protect all and never willingly leave your duties. That oath is bound to your life, so the wielder can never willingly stop his/her duties or else she/he dies. It also can only be wielded by an Incarnation of Yin, and only other Incarnations can chose who is to become Incarnations.

Postremus: EX (Anti-?/Anti-?) - Berserker's True Noble Phantasm which allows her to absorb the energy of others. All energy that is absorbed by Postremus can be used by Berserker herself. However, some energy can only be absorbed directly.

Yep, more of Berserker is revealed. Sooner or later, her real name will be revealed. Also, after they are dead, Assassin and Caster's stats will be revealed. But you know Assassin's and you can probably guess Caster's. Oh, I should probably say this. Berserker can be defeated by any Servant!

Next Chapter: Team Illya/Berserker gains phones to keep in contact, Brother meets Sister, and the Berserker vs Saber fight?