I do not own Sonic the Hedgehog, Fate/Stay Night, or any of their respective characters or themes. All characters and themes regarding the Sonic the Hedgehog franchise are property of SEGA, and all Characters and themes regarding Fate/Stay Night belong to Type Moon.
After my oneshot of the same crossover I decided to try my hand at a more lasting story, unlike my other one, this is not a oneshot this will not be purely dialogue based, and it will have combat like themes, and I can say for certian that this will most likely be rated T, because well... holy grail war and what we all know that entails.
On that note I would like to thank anyone who read my (more lighthearted) oneshot and enjoyed it! As well as thanking you for sticking with me for this story as well. Now on to the story, and there will likely be an author's note at the end!
Please bear with the (admittedly absurd and dark) prologue chapter, (at least the first half) as I needed an excuse to get sonic a place as a heroic spirit.
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The current moment could be what is called the absolute worst case scenario in sonic's entire life, he should know, because it's flashing before him right now. Eggman's most recently summoned monstrosity ended up not only turned out to be an absolute monster full of only malice and murderous intent, but it also ended eggman, the entire race of Mobians,the only consolation was that sonic managed to defeat the monster before it could end the human race.
"Heh... heh..." Sonic barely coughed out "I told you that I'd take you down with me..." Sonic closed his eyes for the last time. To understand how this happened we must rewind back a week.
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It was an ordinary adventure for sonic and his friends... until they found eggman without a pulse in his lab, research data still on the screen. He had somehow managed to extract the purest of hatred and malice of all living beings on earth and given it a body in the form of a robot. A robot who immediately turned on eggman, but unlike eggman's other uncontrollable gods, this was a god of pure hatred and malice, ensuring that it would have revenge on eggman, who made it conscience of its existence.
Not able to waste a second they had to hurry and find this loose monster, an unfortunately simple thing to do, as it had an overly prominant malice toward those with powerful life force which mobians have an abundance of. And sucks the life right out of them leaving no injuries, only a proof that somebody had taken their future from them. Within that week sonic, knuckles, and tails realized something, the creature was actively avoiding them, something that wasn't as common in their past foes, meaning that this foe would only attack when fully prepared, a terrifying thought to Sonic, the hero that he is is impatient, and more importantly is devastated at the loss of even one person he could have saved.
By the end of the week the creature had revealed itself in space, but only after making certain that sonic and his friends were the only ones left of their kind. The day before D-Day, this is the day that sonic lost all hope, the day, the now confident creature ended his friends right before him. Purely because sonic had to choose between saving the world or saving his friends, is why all Hope was lost, Sonic was no longer his confident, wise-cracking self.
Sonic would have opted for saving his friends and the world, but the creature wouldn't have it, having 3 sources of unlimited energy to feed off of instead of one would make the fight impossible. That was the conclusion Tails and Knuckles came to when they willingly gave up the emerald's protection, not before knuckles boosted sonic's super form though.
"The servers are the seven chaos."
Knuckles began while sonic fought and tails defended knuckles "you're sure this will end that monster ri- Ghh!" Super Sonic asked Tails before taking a hit which would have normally gotten stopped by his super form, but the foe was bypassing the invincibility, a work of an artificial god like itself. "Sonic!" Tails exclaimed "it's alright... I'm fine, just hurry!"
"Chaos is power..."
The game of cat and mouse between sonic and this artificial god of malice was getting rough, sonic couldn't land any damage on it, and the blows he did land didn't achieve much other than being readily counter-attacked.
"Power enriched by the heart"
At this point sonic would try a slightly different tactic, namely charging his energy as much as possible "ready..." before releasing it with blinding speeed "go!" Sonic blasted the foe at light speed not doing much but slightly wearing down his foe to make it easier for his friends to wrap up the chant.
"The controller is the one that unifies the chaos, so give sonic the power to defeat this vile foe!"
With that all of the energy was transferred to sonic who now realized what his friends had planned: giving him all of the power in the emeralds at the cost of their protection. "Damn it!" Was all Sonic could say as his friends life force was consumed.
"Chaos..."
Sonic began, intending this to be the final attack to end the monster, which responded full well knowing that if it didn't stop sonic now, that it would be defeated, to which it unleashed its most powerful attack a radial explosion with more than enough force to put a hole into a star... or it would have been.
"Control!"
At that moment, right before the attack reached Sonic, he stopped time, the blast would still hurt to touch, but at this point, that was a dual edged sword he was willing to take in order to end this monster. Sonic floated toward the monster as his life force was being drained, he grabbed the core of it, the robot that was intended to be it's center and "Sorry, but this much malice can't be allowed in one body, so I'm going to take you down with me." Sonic reverses the glow of the chaos energy, him taking in all of the negative energy that his foe had harnessed and giving his foe all of his positive before he blacked out.
When he woke up he couldn't move, metal scraps in front of him as he watched orbit reentry get steadily closer. "Heh heh... I told you I'd take you down with me..." Sonic closed his eyes for the last time, realizing that tails wouldn't be there to catch him on the tornado this time. "Sayonara, I can only hope the world doesn't need another hero."
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Fuyuki City, a small town where our favorite wannabe hero of justice lives. Except that's not who we're focusing on this time around. This time we are focusing an our favorite Gem Magecraft user Rin Tohsaka who was currently attempting to preform a ritual to summon a servant.
after preparing the room for the summoning ritual she double checked everything was in order "preparations complete, time, good, wavelength, ideal, by preforming the summoning at 2 AM when my mana's at its peak, I'll get Saber even without a catalyst!" She then preformed the ritual to a T, and a burst of magic and a gust of wind expanded out of the summoning circle. "That was flawless! I know I drew the most powerful card!" A powerful silence washed over the room. "Huh?"
Then a loud crash from the living room was heard "why?!" Questioned a very exasperated Rin. As she sprinted upstairs and attempted to open the (now broken) door. "The door's broken... Damn it!" To which Rin shoved the door down to view a very... different... sight. Face first on the floor was a blue, spikey, anthropomorphic... thing. Who stood up and dusted himself off like it was nothing. And simply gave a embarrassed grin that clearly says 'I meant to do that...' and then Rin came to a harsh realization 'wait, all of the clocks in the house were an hour fast today... which means it is now 1 AM. Not 2 AM.' "I did it again! What's done is done. Why did you give me that task, father?"
After taking a second to regain her composure "Well? What are you supposed to be?" To which sonic shrugged. "A hedgehog I suppose." He pauses as he realizes something. "Wait, aren't I supposed to be dead? And what's with all of this foreign knowledge about a holy grail or some thing wandering about in my head?" Before the hedgehog could ask anymore questions it was Rin's turn to ask a question "just to make sure, You're my servant right?" To which sonic responded with snark "does that make you my master? Oh how cruel fate can be to this free spirited hedgehog who doesn't like being tied down to anything."
Honestly, Sonic was stalling in an attempt to let the strange new information in his brain fit itself in place and from what he could piece together there's an omnipotent wish granting holy grail at the end of a war where seven pairs of masters and servants fight over the right to have their wish granted. It was then that Tohsaka recovered from her initial confusion and decided to take charge, "are you trying to imply that you'll just begrudgingly acknowledge me as your master and do what you want? You are my servant aren't you?" Rin asserted her question "well according to this fuzzy brain invasive knowledge, it seems so, but I'm not going to be tied down so easily, so you should just sit down somewhere safe and let me decide everything."
Rin's fist clenched and began trembling with anger abundant. "Did that make you angry? Believe me, I have nothing but respect for my authorities, I mean I was summoned to fight for you, so my victory is your victory and I will yield all spoils of battle to you. Sound fair? I mean I'm a hero, and you're... well not that strong looking to me, I'm not one to put a maiden in danger." Sonic reasoned, from what he gathered from his newfound knowledge the world is an overall happier place now than when he was fighting eggman, even if a bit corrupt.
As long as he gets to stick around and protect the peace he wouldn't mind giving away a free wish, because as much as he wanted to he wouldn't just wish away his friends death that were used to defeat an absolute evil.
Although sonic wouldn't get to gather his thoughts for long as his last comment was the final nail in the coffin as Rin's anger overflowed. "That's it! So that's how the first one of these is going to be used?" Sonic stood at attention very quickly, "woah woah woah, you can't be serious, you're going to-" "Shut up! You're my servant! And that means absolute obedience to everything I say!" Magic expanded from her command seal decreasing her count by one and it hit sonic "seriously? You'd be that impulsive that you'd use one of a genie's 3 wishes with that broad of an order? I thought I was impulsive, so fine fine, I give in, I'll let you give me orders and fight, as long as you don't get yourself killed and keep suppling me mana. Just don't waste anymore of those, they're important!" To which rin only responded "hmph, I thought so." And Sonic could only think three words to that 'ow, the edge.'
"Wait, you aren't saber are you?" "Dunno, I don't use a sword outside of one rare occasion, or a spear, or cast magic, the only thing I rode is a biplane, I'm not op at the cost of my sanity, I'm not stealthy, and I don't use any ranged weapons. So, I'll let you pick your poison I guess."
"By the way, what heroic spirit are you?" "If you don't recognize me from the get go, I doubt it matters much, but my name's Sonic the Hedgehog." "Argh of all the spirits to summon I get the whack job, what's worse is I can't even know how powerful you are." "What do ya mean, you summoned me so I'm obviously the strongest!" At that Rin thought 'well at least nobody else will know who he is if he told me and I don't know.' "Anyways for your first job." "You're sending me out to fight already? You're more impatient than I am!" He then caught a broom and dust pan that made their way to him. "You're going to clean the living room since you made it a mess." To which sonic questioned "Lady, who do you think that I am?" "You already told me that you're Sonic the Hedgehog." After that Sonic just sighed and shrugged "well you aren't wrong, so I guess I'll get onto that now."
After leaving sonic to that Rin went to bed and muttered to herself "Father, the battle I have been waiting for for ten years is about to begin... my Holy Grail War... and with that final thought Rin dozed off.
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Whew! That was along and probably boring prologue! I say that not for the first half, but the second, as it basically parallels the source material, but I figured that for the prologue that I shouldn't deviate too much this early on. As for the first half, as I said before: while it may be 'too dark too edgy' I did need an excuse to have Sonic summonable as a servant.
Also, were you surprised? Did you expect sonic to get summoned as Shirou's servant? Well, you'll get to see the plot deviation soon, I don't want this to be a carbon copy of the source material, so please be patient as I figure out where I want this to go. Please review this chapter and tell me what I can improve on and what I'm doing good on, I'd appreciate it!
Until next time your friendly Biscuit will see you next chapter!