"However, at the time this land was in turmoil, so much war and blood shed occurred on these grounds. Poseidon knew Britannia could never rule with such a destroyed kingdom, and so he sought to bring peace to the land. And to do that he would need a weapon, a son, a demigod. He bedded a woman named Igraine Pendragon, giving birth to a son, Arthur Pendragon."
Percy's eyes widened, "King Arthur is my brother?! What the Hades?!"
The Fates seemed to smile, "yes, Arthur Pendragon was a demigod, and a powerful one at that. He united the kingdoms, and while eternal peace wasn't gained, it was a powerful start to Britannia's kingdom. And now she stands, ruler of one of the most powerful nations in the world. And that is mostly in part to Poseidon, her father, and King Arthur, your brother."
Percy blinked, "holy shit….King Arthur is my….wow….wait, does that mean Excalibur is real?!"
The Fates nodded, "it is. But it has been lost to time, no one knows for sure where it lies."
"I see...wait, does that mean Merlin was real?!"
"Yes, Merlin was real, he was a very powerful wizard and he knew very well exactly what was going on. He knew about Britannia and off Arthur's true parentage. He knew all of this, and he swore to keep it a secret."
"Cool," Percy nodded, "but, why are you telling me this? How does this help me survive 15 bloody years in the past?"
"Simple, you see Percy Merlin wasn't the only wizard, he was just the most powerful one."
"So you mean magic is real? Wizards are real?! Are you messing with me?!"
"Is the demigod son of a Greek God really asking us this?"
"...alright then, please, continue."
"Understood. Arthur brought peace to the land and this allowed Merlin and the other witches and wizards to go into hiding from the mortal world. They realised that the world was changing and humans were slowly becoming more and more afraid of them. So they resolved to slowly die out in the shadows becoming nothing more than myths and legends. However they did not go extinct, they thrived, and now a world of witches and wizards live in London, hidden from the mortals."
"But how is this possible? I have never heard of these guys!"
"You haven't Percy, because you aren't a part of their world ether."
"What? Why not? I'm a bloody demigod, don't I fall into the same category as them?"
"No, you don't. Your world, our world, is as much hidden from them as they are from humans."
"Why is that? They can use magic right? Then how can they possibly not know about us?"
"We try very hard not to let the two worlds meet, if something like that happened….apocalyptic would probably be the word to describe it. Wizards are very...prideful creatures Percy. If they one day find out that there are some things out there that can kill them without a thought they would not rest until they kill that thing first, or try and stick their nose where it doesn't belong. It is best to stay away, unless it is unavoidable."
Percy raised an eyebrow, "they way you said that last thing tells me I might not like where this is going."
"You need to be hidden Percy, no one from our world must be able to find you. The magical world will be able to do that, and while there you will also be able to learn many new things about this world Percy. Dragons, spells, curses, teleportation, even a wand."
Percy would be lying if he said he wasn't the least bit curious what this whole hidden magical world world was all about.
He had always found his own divine world amazing, surely a world made by humans would be equally exciting.
Percy sighed, "I don't exactly have a choice in the matter do I?"
"No Percy, you don't. The divine world walks among the mortal world freely, the Mist protects them and they have no risk of discovery. But the wizarding world, well they can see through the Mist, a God or Goddess would be spotted instantly. You must not be seen Percy, or else the victory you and all your friends fought for, or will fight for, will all be for not."
Percy rubbed his temples, "you three are a pain in the ass. Has anyone ever told you that?"
"Nearly every single human across human history," the Fates grumbled. "Will you do it?"
"Yeah," Percy shrugged, "why not. Might be fun. Who knows maybe in a few years I might actually like living there." The Fates nodded. "Hey, wait, I have a question, is there any chance that I could learn a little magic while I'm there?"
Fates smiled, "we thought you would never ask. There is a place that teaches magic in this world, a school called Hogwarts."
"Okay I'm going to stop you right there. What? Hogwarts? Seriously? That sounds like a disease a pig would get after it had sex with Aphrodite!"
"Yes, the founders were very...peculiar people. But rest assured the school is the finest there is in the country, let alone all of Europe. Although you are behind on six years of education… they start teaching children when they are 11 for seven years."
Percy blinked, "well shit. What exactly are we talking about here? Charms? Spells? Do you think I could just wing it?"
"No chance in Hades," The Fates shook their heads. "If you were a child of Athena you would have a slight chance. But-"
"-You don't have to say it, I know, I'm a seaweed brain," Percy groaned, "so that's out as well huh?"
"Not necessarily," The Fates then turned to each other and began to whisper in hushed tones, Percy looked on in confusion before they broke apart and they spoke once more, "we believe that you should be able to catch up. The month is currently february, you have six months to catch up."
"So you want me to cram in six years of knowledge in six months time?"
The Fates nodded.