This meant to take place after the end of the House Of Hades, while the crew is still on route aboard the Argo II. I may have to rework this fic slightly after I read the last book.

After rescuing Percy and Annabeth, and saying goodbye to Coach Hedge, Nico, and Reyna, Leo sat at the front of the Argo II. He was fiddling with the Archimedes' sphere, and his experiences in this most recent chapter of his life had changed him. He was lost in thought, so much so, that he didn't notice Percy coming up behind him.
"Hey. I heard you ended up on Calypso's island."
"Yeah. How did you know? I haven't told anyone."
"From your appearance in Malta, Jason guessed that you had ended up meeting her. Your hands were way too still."
"I see. You know, you broke her heart."
"Yeah, I know I did. I didn't have much a choice. Kronos probably would have won if I hadn't come back. I also asked the gods to release her, but evidently this war got to them before they could release her."
"You came back because of Annabeth."
"That was most of it. But I would have come back even if Annabeth hadn't provided any motivation."
"Why is that?"
"It's in my nature. I can't walk away. Not when other people are depending on me."
"You were the demigod of the prophecy."
"Correction, I was the demigod of the Elder Gods mentioned. Luke Castellan was the demigod of the prophecy."
"Luke Castellan?"
"He served as the host for Kronos in the last war against the Titans."
"What!? Why?"
"After his mother tried and failed to become the Oracle of Delphi, he felt the gods, specifically Hermes, had abandoned him.
"That's rough. What happened to her?"
"She went insane. She would spout random nonsense about Luke's future. It scared him to no end. And then he lost Thalia."
"Thalia? Jason's older sister?"
"Yeah. She got turned into a pine tree."
Leo decided not to press that story any further. But it seemed oddly normal. So a demigod could get turned into a pine tree. That seemed straight out of a mythological book, but then again, considering their lifestyle...
"So you left and came back because you were the demigod of the prophecy."
"Yes."
"If you hadn't. Would Nico have been the demigod specified in the prophecy?"
"Probably. It's hard to say now with Jason in the equation, but at the time I thought without a doubt that Nico would become the demigod of the prophecy."
"And you didn't want that."
"No. Not after I lost his sister."
"You lost his sister?"
"I made a promise to him. I couldn't keep it."
"Speaking of promises unable to be kept..."
"Let me guess, you made one to Calypso."
"How did you know?"/
"Your eyes. So what was the promise?"
"I promise I would come back for her."
"Even though no man ever finds Ogygia twice?"
"Yeah."
"Well, I hope you're able to back it up."
"Hehe. She's still not completely over you."
"Really?"
"While I was there, Gaea offered her a choice."
"And what was that choice?"
"If she killed me, she could have you. To be honest, I thought she was going to do it."
"Why?"

"It's me. And you're you."
"So, you don't think you're that valuable?"
"Hey, man, I'm just the seventh wheel. Alone among the couples. So what's your experience with Calypso?"
"Well, let's see. There's not much to tell. Annabeth kissed me. I blew up Mt. St. Helens. I woke up on Ogygia. Hephaestus came by, informed me of the outside world. I chose to leave. I landed at Camp Half-Blood right as they were about to light my funeral pyre."
"Seriously?"
"Yeah, that's it."
"You crashed your own funeral?"
"Yep. You wouldn't believe how pissed Clarisse and the rest of the Ares kids were."
Percy said it so nonchalantly that Leo couldn't help but be impressed. That must have been a one of a kind experience.
"And what was Annabeth's reaction?"
"She punched me."
"I'm not surprised."
"Well, it's my turn to head the ship. You haven't slept since Annabeth and I returned." Percy said.
Leo continued to fiddle with the Archimedes Sphere.
"Go."
"He's right, Leo." Jason had arrived.
"Yeah, okay." Leo wasn't about to contradict Jason on this call. He went below deck. On the way to his home, he walked past Annabeth.
"I thought you were supposed to be asleep." Leo asked.
"I could ask the same to you. It's been over twenty-four hours since Percy and I came back. And you'd been sitting at the head of the ship all this time."
"Well, I was on duty until Percy and Jason threatened me to go to bed."
"Leo, here's a drachma."
"What? Why?"
"You might want to make a call."
Annabeth winked and headed above deck. What was that all about? Leo headed to his room, and collapsed onto his bed. On his nightstand, there was Coach Hedge's prism, and a flashlight that had been pulled out of his tool belt. Jason had been right. He needed his rest. His dreams were unbelievably simple. He was staring at Calypso.
"I made a promise. I'm going to come back."
"I know you will. But first things first, you moron! WAKE UP!"
"Huh?"
Leo shot up. He had no idea what time it was. He turned to see the flashlight on, shining through the prism. And there she was.
"I've heard of someone sleepwalking before. But I've never heard of someone sleep Iris-dialing before." Calypso teased.
"What? I called you in my sleep."
"Yes, you did."
"I guess you left quite the impression on me."
"I'm more surprised by the fact that this works."
"What? You mean in the 3000 years you've been stranded on Ogygia, not once has anybody tried to Iris-Message you?"
"No. The Gods only ever visit in person. I guess the Gods never accounted for the fact that someone might want to Iris-Message me."
Just then Percy walked in.
"Hey, Leo..."
He stopped and sweatdropped.
"Is that...?"
"Yeah, man, it is."
Calypso raised an eyebrow. She looked at Percy like he was unpleasant gnat.
"So... the Gods haven't released you yet?"
"Oh, yeah. I'm just staying here on Ogygia because if I leave I'm going to get homesick... OF COURSE I'M STILL STRANDED HERE YOU DINGBAT!"
Leo was glad that that anger snarking wasn't directed towards him. Percy backed away slowly. He almost would rather have faced Kronos again.
"Yeah, Leo, I'm going to tell the others you're going to be late to dinner."
Percy left.
"I think Percy was scared of me." Calypso grinned.
"Yeah, yeah, he was." Leo agreed.
"Do you really believe that, or are you just agreeing with me because I'm attractive and you're also a little bit scared of me?"
"I don't just agree with girls just because they're attractive."
"Awww..."
Leo blushed.
"But I AM a little bit scared of you after that look you gave Percy."
"Jerk."
"So, how long was the Iris-Message before I woke up?"
"I don't know. I watched you sleep for quite awhile though."
"What?"
"Hey, I was amazed I could get Iris-Messages!"
"I still can't believe no one ever tried before."
"I don't think it ever occurred to anyone. Like I said, the Gods can come here whenever they want. Some do, some don't. And most Heroes who leave hardly spare me a second thought."
"Well, that's changed."
Calypso smiled.
"Indeed, it has. So how are your friends?"

"Well... let's see. None are in Tartarus in anymore. So we got that going for us."
"What!"
"Yeah, listen, I wanted to show you something."
Leo rolled his sphere forward. He had wired into it a portable wifi port.
"This is Google."
"Google?"
"It's the Internet. Humanity's information exchange network."
"I see. And what do humans use it for?"
"Do you know what a cat is?"
"Yes."
"Cat pictures."
"Are you serious?"
"I'm serious. Most of the Internet is either porn or cat pictures."
"What is porn?"
"Uh... that's not important."
Leo felt like he had dodged a bullet there.
"But back to the cat pictures, they all have captions like "I can haz cheeseburger?"
"Cheeseburger?"
"Okay, first order of business, when you get out of there. We're having cheeseburgers."
"That sounds good."
He chuckled.
"What?"
"I don't know why, but just the thought of you, eating cheeseburgers makes me crack up."
"Okay. On one condition."
"What's that?"
"We ride in on your dragon."
"Festus?"
"Yeah."
"Okay, I know where we're getting our cheeseburgers then."
"Where?"
"McDonalds?"
"Why?"
"Because they have HAPPY Meals."
"Leo... that was terrible."
"I'm sorry."
"I liked it anyway."
"Oh, okay."
"Did I mention that Nico once summoned the dead with Happy Meals?"
Percy shouted through Leo's door. "I came by to give you your dinner or else."
"Or else what?"
Leo said, opening it.
"Or else Piper was going to blast down your door with her cornucopia of food. And now I'm leaving again."
"You don't want another scary stare, do you?"
"No, I do not."
Calypso give him one anyway.
"I'm outta here."
The two shared a hearty laugh. Hearing her laugh lifted Leo's spirits immensely.