So, this is my baby... A Mark of Athena fanfic with a twist. I added my (very important) OC and really hope you enjoy this. It's going to be quite long, so please stick with me and review! I really want to know what you guys think of it! I'll be updating soon...

Disclaimer: I only own my OC (and some of the plot), nothing else

The Mark of Athena : Leo and Penelope's story

1. Leo

After working for eighteen hours straight on the Argo II, even Leo had had enough. Enough of fire, metal, shiny objects and tools and if he was saying that, it definitely meant something. After all, he was a son of Hephaestus, the god of forges, and normally he loved working on his giant trireme.
But no, this time it had just been too much. He had had almost no break and his back was aching, his fingers were completely filthy and his head hurt.
What Leo needed was a break, even if that meant having to face Annabeth, who was becoming something of a slave driver. Of course Leo could understand her wanting the Argo II to get finished, so that they could fly to Camp Jupiter and rescue her boyfriend, Percy Jackson, who had been missing for months, but sometimes even Leo needed to get away from Bunker 9.
Piper and Jason, his two best friends, had suggested he come with them on a picnic they were planing on having underneath Thalia's tree on top of Half-Blood Hill, but Leo had politely declined. For one thing, he knew he'd just be the third wheel, even if Piper and Jason were trying their best not to make him feel that way.
It had gotten awkward again since they'd restarted dating two months ago, and Leo wasn't in the mood for that.
And for another, he knew exactly where he wanted to be right now. Somewhere that had nothing to do with fire, that wasn't cramped and that was, hopefully, void of anybody who could annoy him. What Leo wanted was the ocean. Luckily, he had one just a few minutes away, so that's where he was heading.

When Leo arrived at the beach, it was just as he had hoped. There wasn't a person in sight, and so he put down the blanket he'd brought, opened his cool can of soda and flopped down, instantly feeling his muscles relax. He felt completely at ease here, at the sea, with the slight ocean breeze ruffling his hair a tiny bit, blowing away his headache.
A few seagulls flew overhead and in the distance he could hear the sound of the pegasi flying.
After a while, Leo sat back up and stared at the ocean in front of him. He thought of Percy Jackson, Annabeth's missing boyfriend and a son of Poseidon, the god of the sea. That guy must be really powerful, Leo thought, if his dad could control all of that vastness in front of him.
He hoped Percy really was at Camp Jupiter because he didn't think Annabeth would cope if he wasn't and also, he would feel like all the work put into the Argo II would have been for nothing.
But no, Leo told himself, none of that. Percy'll be there and they're all be on their happy way to the ancient lands before long. Ready to meet the most dangerous threat any of them had ever encountered. Didn't that sound like fun?
The ocean was a grey blueish colour today, and not a living thing was in sight as Leo's eyes scanned the horizon.
Wait...actually there was something in the water, although Leo wasn't sure exactly what is was.
A dark shadow, like a bundle of robes...And then, all of a sudden a hand, a thin human hand bobbed out of the water, before sinking under again. It was a person, and by the looks of it, that person was drowning.
Leo sprang up and raced to the water. He had barely time to think about how a boy with a fire affinity like him probably wasn't the best person to help a drowning one, but there was no time.
He plunged into the icy water and swam, as fast as he could, towards the dark shape, which had sunk further under water. His heart was racing and Leo could hear the roaring of the waves in his ears.
Adrenaline helped him to swim even faster, and before he knew it, he was where he had seen the hand go under. He looked down and there, maybe five feet below him was the dark bundle of cloth, with human limbs and a face sticking out of it, no longer thrashing around.
Leo dived.
His hands worked forcefully as he swam towards the person. Just then Leo made out the face and for a moment, he forgot he what he was doing, even that he was underwater.
It was a girl, and a very, very pretty one at that.
She had long, dark hair, that swirled around her face, which was pale in the water but perfectly featured. Her eyes were shut, but Leo knew they would be startling when they opened.
If they opened.

That thought brought Leo back to his senses, and he grabbed hold of the girl as best as he could and swam towards the surface, his lungs burning for air.
They broke through and Leo gulped down big lungfuls of fresh, ocean breeze, as he put his arm around the girl and swam backwards, like Piper had shown him.
It was difficult, but eventually they reached the shore, neither of them moving for a minute.
Then, Leo sat up, and carried the girl further up to where his blanket was. His whole body hurt from the exhaustion, but Leo knew the girl wasn't out of danger yet. Her body was ice cold and her lips had turned blue. Leo checked her pulse, it was very fain, but definitely there.
Right, he thought to himself, trying to sort out his jumbled up thoughts. We need to get you warm.
He looked around for someone who could help him, but his wish from before had been granted, much to his agitation. There wasn't a single creature in sight.
He was on his own.
First, Leo wrapped his blanket around the girl as tightly as he dared. Then, on impulse, he put his hands on the blanket, and imagined them getting warm.
Not catching fire, just transporting a lot of heat, through his body and into the girl. For a second nothing happened.
Then, gradually, his handswarmed up and, with an immense effort to stop them from going up in flames, Leo warmed up the girl's body.
It had worked! Leo felt elated for a second, until a tiny movement caught his eye.
The girl's eyes opened, only a fraction, but enough for Leo to see a glint of intense turquoise.
Her eyes focused on him, and a troubled expression crossed her face.
"Leo?" she mumbled and then passed out again.
Leo was stunned. How did she know his name? He was sure he would have remembered her if he'd met her before today.
Maybe his mind, as exhausted as it was, had tricked him and she hadn't said his name at all...
He decided to put the matter aside for a moment, as long as the girl was still in danger.
He needed to get her to an Apollo healer, and quick, but Leo doubted he could carry her there. The rescue and the heating up of his hands, along with his 18 hour shift before had all but knocked Leo out.
Just then, as if some god had sent her (which, come to think of it, maybe one had) a wood nymph walked over the crest of the little hill before them and towards the water, maybe wanting to talk to the water spirits. She didn't pay them any attention until Leo yelled
"HEY! Over here! Help!"
Then, she hurried over, looking very confused. Leo didn't give her any time to talk.
"Go and get some Apollo kids, quick! This girl almost drowned and she hasn't moved since. Hurry!"
Without a question, the wood nymph hushed back the way she had come and disappeared.
Please Dad, Leo prayed fervently. Please let the girl be okay.
He didn't know why he cared so much, but he was suddenly terrified that the girl might not make it.
Afraid of her turning cold again, Leo held her close, trying to think positive, warm thoughts.
Just then, a group of demigods hurried over to him.
"What happened?" one of them, Ryan, asked as the others surrounded the girl. Leo told him the story and Ryan looked confused and scared.
"That's a long time to be under water." he said, anxiously. "And she didn't say anything?"
Leo hesitated. Should he mention her saying his name? A feeling in his gut told him not to, and so he decided to wait until he knew what that was all about before telling anyone else.
"No" Leo said. "She hasn't even moved:"
"Right." Ryan told his siblings.
"We need to get her into the Big House, asap! Come on." A few demigods hoisted the girl up and ran off, but Ryan turned to Leo before he left with them.
"You okay, Valdez? You look pale yourself."
"I'm fine" Leo answered, untruthfully. "Just...take care of her okay?"
Ryan nodded, and handed Leo a square of ambrosia.
"I will. Just eat some of that, right? We don't want you passing out as well." Then, he hurried after the others, leaving Leo alone again.
There was only one thought in Leo's mind, as he ate the ambrosia and made his own way back to camp, as quickly as he could: Who was that girl, and where had she come from?

So, that's the first chapter! Follow to find out exactly who this mysterious girl is...