Disclaimer: I do not own anything. Harry Potter is owned by JK Rowling, Fate/Zero Fate/stay night and Fate/hollow ataraxia are owned by Type-Moon, and all is owned by Gilgamesh
Chapter One: The King's Arrival
When Gilgamesh woke up, he found himself on a hill. He saw a mongrel staring down at him. He quickly stood up. No one stares down at him!
"Answer me mongrel. Where am I?"
The girl didn't seem to be fazed by what he called her (Good. She knows her place). She answered him, "you're outside our house."
Gilgamesh looks at the rook shaped house in front of him that the girl was referring to. Then he thought to himself, where is he though really? The last thing he remembers is– he shuddered at the thought, getting beaten by that faker. He should be mad, but instead he could only sigh and accept the red head as a worthy opponent. After that humiliating defeat, the grail, or rather, the contents of the grail, tried to make him it's new host. But not only is the King of Heroes incorruptible, but a Servant taking over another servant is simply impossible. He thought that act would've destroyed them both, but instead, he ended up here in… wherever the hell this place is.
He noticed a man with long blond hair similar to the girl's coming out of the house. The younger blond ran towards him.
"Daddy! That man fell down from the sky!" She told him, pointing at the King (he would've killed her right now for pointing at him like he's some lowly peasant, but he has too many questions to bother).
"Oh dear. Bring him inside. He might have been dropped by a Blibbering Humdinger."
They let Gilgamesh in the house (not that he needs permission from these mongrels. They're borrowing his land after all). While the inside of the home is very lackluster, his attention was instead drawn at one of the newspapers scattered throughout the living room. For one, the pictures are moving. That's strange. He's never seen Magecraft like that before. But stranger is the date on the newspaper.
August 13, 1995.
"Is this newspaper recent?" He demanded.
"Why yes," the oddly clothed man told him. "It's the latest issue of the Quibbler."
More questions filled the King's head. Did he end up 10 years into the past? He read the contents of the paper and found that he's not familiar with these events. While Gilgamesh didn't really care about mongrel affairs, he did keep tabs of any important events, both in the Mage's Association and outside of it. Yet he doesn't know anyone named Harry Potter (who if the paper is to be believed, is quite famous) and he doesn't know anything about the Ministry of Magic nor is he aware of this apparent trial about underage magic (which as far as he's concerned, doesn't even add up. Kirei spent 10 years teaching the Tohsaka girl magic, and there's also that faker who is self taught, yet this trial implies that anyone 17 below can't use magic outside of Hogwarts, whatever that is.). There can only be one explanation for this.
The Grail has somehow sent him into an alternate reality.
As if the mongrel is reading his mind (who gave her the right!?), the young girl asked him. "Is it possible that you're from another dimension?" He stares at her in surprise. How did she figure that out?
"If this paper is to be believed, yes I am."
The two mongrels perked up (as they should have. They're in the presence of a King after all). The King found himself bombarded with questions about dimension hopping and Second Magic. What was left of his patience quickly evaporated.
"ENOUGH!"
His shout silenced the two, putting them in their place.
"You mongrels have no right to hound me like wild dogs, for I am the one true King of this world! It doesn't matter how the timelines diverge. I have been King since before the age of man! Moreover, if you cannot discern my identity, then you are not even worth the dirt in my feet!"
The two looked at him, and then bows down. It's the reaction that he wanted, but not what he was expecting.
"This is a better discovery than I have thought. You're not only from another world, but you are someone from the past."
Gilgamesh just stares at him. He continued, "Such arrogance can only come from one person."
It was the girl who finished the thought. "You're the King of Heroes. You are Gilgamesh."
Gilgamesh was silent for a moment, and then he laughed. "And here I thought you're just some lowly mongrels. You still are mongrels, mind you, but you are able to figure out who I am based on your perceptiveness. For that you are worthy to be called my retainers."
The man, still bowing, asked him, "Now what do you want to do, your Majesty?"
Gilgamesh didn't even need to think about his response. "I suppose you can show me this world of yours. If this is to be my new kingdom then I should know all I can about it."
Gilgamesh sighed in disappointment while the girl named Luna watches him. You think after spending a week in a new world, he'd find anything interesting. Instead, all he found is stupid mongrel politics, boring magic that is only showy for the sake of being showy, and rumors of some dark mongrel coming back to life (if the rumours were true, he could easily kill him with the Gate of Babylon. Not that he would even bother). The only saving grace is the food. They're not as good as the ones served to him back in Uruk, but they are a delight nonetheless.
That's it then. Kirei is dead, the grail is gone, and he's in an entirely foreign land. He might as well start a new life here. In the snap of his finger, a beautifully decorated bottle materializes on his hand.
"What is that?" The girl asked him.
"The Potion of Youth," he explained. "I plan to start anew in this world, but I cannot do that with the way I am. As a child, however, I can live my life in leisure. Undetected in plain sight." The girl nods in understanding. Gilgamesh drank the potion, and in a matter of seconds, his body started morphing. He can feel his bones getting smaller. His limbs retracting to his body. When he yelled in pain, his voice became higher. Eventually, The twenty-something year old King of Heroes is gone, replaced by a small child.
"Hello there," Luna said, extending her arm, as if meeting a new person. Gil eagerly shakes her hand.
"Sorry about my older self. He can be a prick sometimes." That's a lie. He's a prick all the time.
"It's alright," the blond assured him. "He's just a product of his time, is all. Now, what would you do in your new life?"
Gilgamesh thinks on that. What would he do? Obviously he'll stay in the magical world. He's already had enough of the normal one and this world is closer to how it was when he was alive. He'll live a life of luxury, eating and gambling. Though he is magical. Maybe he should go to that Wizarding School that he read in the Quibbler. Oh how fun it would be to learn new kinds of magic. He looks at Luna and gives her his answer.
"I think I'll go to that magic school. Hogwash, was it?"
Number Twelve, Grimmauld Place
Harry Potter is lying in his bed, reflecting on what he had just seen. Ron and Hermione were made Prefects. He should be happy for them right?
Then why is he instead feeling anger and jealousy. Admittedly, he's been feeling angry all summer, but this feels different. In fact, he's been feeling different since the Trial. At first he thought it was just stress. With all that's happening, he thought it's totally normal to wish Death on the ones who support Voldemort but the Ministry is ignoring. Or wanting those bastards who voted against your innocence to be burned at the stake. But stress doesn't make you feel like beating the shit out of the greatest Sorcerer in the World just because he ignored you. Or wanting to strangle your best friend to death and throwing his corpse in the Fireplace.
Harry shakes away the thought. He shouldn't be thinking this. Ron is his best mate. He shouldn't get all riled up just because Ron finally beat him at something. He should be proud. Supportive, like a good friend would.
"But you're more than deserving of that badge!" The voice in Harry's head told him. "You defended the Philosopher's Stone! Killed the Basilisk! Drove away the dementors and fought Voldemort in the graveyard! What has that git done in his life? Won a game of Chess? Fred is right. Who in their right mind would pick Ron? The old man has truly gone mad!"
As he thinks these horrible thoughts, the scar on Harry's forehead begins throbbing in pain. He really should ask Dumbledore about this.
"But the old loon is ignoring you too, remember?"
Harry groans and plants his face on the pillow. Then he heard Ron's footsteps on the stairs. Harry collects himself and silences his inner ramblings. He really hopes these murderous thoughts are just that. Thoughts that would soon go away.
Not long after Gilgamesh turned himself into a child, Xenophilius sent an owl to Hogwarts, informing them of a relative from Japan who will be staying with them and enrolling at the Wizarding School. After a visit from one of the teachers confirming his enrollment, and being given a list of his and Luna's school supplies, Gilgamesh and the Lovegoods went to Diagon Alley. To save the Lovegoods some trouble, Gil paid for his own books and robe. As for a wand, he finds that the Gate of Babylon has synched with this world's treasures, so he has access to various ancient wands. With that out of the way, Gilgamesh spent the rest of the day exploring Diagon Alley, trying out all the shops.
Not long after that, the first day of school has arrived, and he and Luna (who he now affectionately refers to as his Onee-chan) found themselves in the Hogwarts Express. They found a compartment, and Luna began reading her copy of the Quibbler while he eats the chocolate bar that he brought. However, they weren't alone for long, when three people entered their compartment. One is a red headed girl. The other is a slightly chubby round faced boy. The last one however, a scrawny boy with glasses and a lightning shaped scar on his forehead. He recognized the boy immediately.
"Hi Luna. Is it Okay if we take a Seat?" The redhead asked his sister. She nods and the three take their seats. Gil found himself in the middle of the two girls. Harry Potter on the other hand, sat opposite to Luna, the other boy sitting beside him. After a very awkward introduction, there was only silence. Then, the trolley lady came and They all bought food. Gil joined the trio in trading Chocolate Frog Cards (but he held onto his most priced card, King Arthur. Though it's the male version of his queen, it's the closest that he can get).
A while later, they were joined by two other kids. Another red headed boy and a brunette girl. Gil ended up sitting on his sister's lap for the rest of the trip, which was interesting, to say the least. He heard Luna's laugh, which would have made his older self proud (or annoyed for stealing his laugh), and he met a blond kid that reminded him of a combination of that weird Matou kid and his older self (That's two now. This trip is reminding him of that asshat a lot more than he wanted to). Once or twice, he felt something strange coming from Potter, mainly when that Malfoy-faker appeared or earlier when they all got covered with Stinksap, but he decided to ignore it. Considering how famous he is, he won't be surprised if he's an amazing wizard, and that was probably just magic that he sensed from him. Very powerful magic.
Finally, they arrived at their destination, and after saying goodbye to Luna and the others, he along with the other first years followed a lady who led them to the boat that the first year's had to take. Soon enough, Gil can make out the castle where his new life will begin. He can finally see Hogwarts. For the first time in a while, he feels excited. He can only wonder what new adventures are waiting for him in this land.
How he wished Enkidu was here.
A/N: I have a question. Does Gate of Babylon have copies like Unlimited Blade Works, or are they the genuine article. What would've happened if Gilgamesh, say, tried to summon Rhongomyniad, a weapon that was still being used in modern times. And can he summon the Noble Phantasm of Servants summoned at the time, or is it gone from his treasury for a while. I'm asking for future reference.