The Explanation
"And who would that be daughter? I believe that he called Hestia his mother" "That seems to be a non-blood relationship, this is the part that I requested Percy to be here for" She paused seeing if anyone else could connect the dots. "I believe William is the son of Poseidon and the retelling of our story with all the details should provide all the information for why I believe this" Artemis explained, Zeus said nothing and motioned for Artemis to continue.
Artemis retold the story of how they met, taking the sky from him, her getting raped, him shaking the ground to try and knock away the cyclops, him helping her through the rapes by holding her gaze, his forced part in her rape and his taking of her virginity. She explained that there was a barrier that had kept everyone except him out. She told them of the days following that and his mountain infused punch while Atlas groped her, which earned William a thankful nod from Apollo who looked pained at what his sister had gone through.
She explained that her Hunters had been chasing him for four years and that she had just captured him today and that was why they were late. "And I-I-" Artemis turned to look at William who smiled at her "And I love him" William's eyes went wide at that as did several others, Annabeth, Hestia and Aphrodite all let out excited squeals. "Plus his eyes flow with the ocean just like Poseidon and Percy's do"
"I must agree with Artemis, the facts to all point towards barnacle breath as being the boy's father" Athena agreed. All eyes looked to Poseidon, who looked very confused as he shifted through his memories trying to recall the boys mother. Suddenly his eyes snapped open and he walked towards William, who also stood up on guard, not sure of Poseidon's intentions. Then Poseidon shrunk down to human size and placed his hand on William's forehead and closed his eyes. "It's true, he is my son" He said after a minute.
"Dad, what do you mean? He's the same age as me. I thought you loved my mom" Percy said upset. "I did my boy, I didn't even know William existed. I slept with his mother after the third time your mother rejected my marriage proposal. I went out and got drunk and obviously created another son" William didn't know what to think about this, on one hand he was not only an accident but he was a bastard. On the other hand he finally knew who his dad was and he already had the beginnings of a relationship with his new brother.
"William, I am deeply sorry that I have done nothing for you in your life, I truly had no idea about you, until now I didn't even remember that night with your mother. I can't tell you anything about her other than that she was beautiful. I don't expect you to forgive me but kno-" William jumped at Poseidon embracing him in a hug, hearing the sincerity in his voice he knew he meant it. "It's alright dad, I've found a pretty great mom now" William said smiling at Hestia.
"As for everything else, yeah my childhood was hell but I'm not sure that I would trade it for anything else. Otherwise I meant not have ended up on that mountain" William said turning to the beautiful goddess behind him. She blushed and smiled back at him.
"Yes back to that matter" Zeus said breaking up the reunion. "We will speak later" Poseidon whispered to William before returning to his throne "I do not like that you held this information from me daughter, nor do I like what it entailed. However, if you believe this demigod to be the one for you, I will not stand in your way. I will be watching you closely though boy, my trust must be earned" "I would have it no other way Lord Zeus, a father should always watch over his daughter" William agreed. Zeus huffed in grudging approval. "This meeting is adjourned go join your children in celebration" he said before flashing away.
The other gods also flashed away, leaving just Hestia, Artemis and Poseidon alone with the three demigods. Poseidon went over to talk with Hestia wanting to know everything that she knew about William so that he could start to form a relationship with him as soon as possible. Artemis just sat on her throne as she watched Percy and Annabeth approach her demigod. "So I guess we're brothers now" Percy said awkwardly not knowing what to say. "Seaweed brain" Annabeth muttered.
"It's good to see you again William, I didn't recognize you when you walked in, you look good" Annabeth said. William heard a low growl come from Artemis, only he seemed to hear it, so he decided to de-escalate the situation as soon as possible. "You mean I don't look the same? It's not like everything about me has changed since we last met" I said sarcastically.
"You guys look pretty cute together though" I said and Percy smiled pulling Annabeth close and smooshing their faces together. "You mean like this?" He asked laughing as Annabeth pushed him away. "Double seaweed brains" she said a little louder this time, before kissing Percy on the cheek, a blush spread across her face. Artemis must have seen this too as he felt her calm down behind him. "I've never had a brother before" William admitted. "I have, he's a cyclops though, so it's a little different" Percy said laughing at William's face. "It'll be fun to have a human brother tough!" Percy said quickly, "Camp is going to be way more fun with someone else in the cabin, though I guess that means that I'll have to clean up a little. Oh and Blackjack will be pretty excited too, can you talk to horses? We will definitely kick butt at all the inter-cabin games too now that it's not just m-" Annabeth elbowed him in the ribs to stop his rambling.
"That all sounds awesome Percy but I'm not sure that somebody is going to let me hang around camp, she seems to think I'll run away again" William said a little sadly, what Percy had talked about sounded nice. An actual bed to sleep in, a brother to do all kinds of things with. Artemis, hearing her being talked about, shrunk down to her almost nineteen year old form to be the same age as all the demigods in the group. She walked up to them and realized that she was now the shortest one at five foot four, William's six foot three towering over her, was nearly identical to Percy's height.
Artemis walked over to the group and wrapped her arms around William's arm and laid her head on his bicep. William smiled down at her as she joined them. "I told you she wouldn't kill you" Annabeth said smugly with a smirk. "What do you mean" Artemis questioned. "Annabeth tried to convince me while we were chained up that you would understand and wouldn't kill me. I obviously didn't listen to her" William confessed. Artemis looked up at Annabeth, "Thank you for trying." Annabeth smiled, "I had to, I could tell you had at least mild feelings for him, and I could tell he was full out into you." A massive blush spread across William's face. "That's my Wisegirl!" Percy said planting a big wet kiss on her cheek. Making everybody laugh.
"Well Percy I hope that you bring William to Atlantis to visit soon" Poseidon said to his elder son. "I'll talk to you soon William, I intend on making up for lost time" He said to the younger before walking out into the party.
William turned to Hestia "Go make some new friends and spend time with your lady, you deserve it, we'll talk later" she said kissing him on the cheek before also disappearing.
"I'll introduce you to all our friends! Come on!" Percy said excitedly before the group of four headed towards the throne room doors.