A/N: Saw a post on tumblr speculating if the characters of HoO got possessed by Gaia or by the eidolons. Someone suggested Piper getting taken over by Gaia and fighting Jason, so decided to write a fanfic about it, but decided to make the eidolons possess her instead.

Song: 'Close Enemies' – Example (sorta fitting).

Piper

Piper needed fresh air. She felt sick. She had a horrible headache. It felt as if someone was digging a knife into the back of her head, twisting and turning and digging in further, causing her more and more pain as time went on. And, she was sick and tired of the arguments in the dining room of the Argo II. Leo, Frank, Hazel and Nico refused to shut up for more than five seconds. They kept arguing over and over about the same stupid things, when more important matters were at hand. Fed up, Piper shoved her chair away the table and marched away down the hall, clutching at the side of her head.

The Argo II was currently sailing through the sky above Italy, Rome and the disaster that had occurred there far behind them. Piper stood at the edge of the ship, leaning over the side. She tried her hardest not to vomit, forcing herself to swallow it down. She doubted that an innocent Italian on their daily commute home would appreciate having demigod sick on their windshield. Instead, she slid down against the wooden supports lining the ship and put her head between her knees.

'Pipes?' a soft voice asked. She glanced upwards and groaned when she saw Jason standing on the deck in front of her.

'You might wanna go down below,' she murmured, shoving her head between her knees again. 'This isn't going to end well.'

'Do me a favour and don't vomit on the deck,' Jason said with a light laugh. He pressed a metal bucket into Piper's hands before sitting down next to her. 'I don't want to give Leo an excuse to swab the whole ship.'

'When's he made you do that before?'

'Why do you think I didn't see you until dinner last night?'

'What did you do?'

'A few Stymphalian birds attacked. Left a load of bird poop all over the place.'

'Nice.'

The two of them laughed together. Laughing felt good. While she laughed, Piper momentarily forgot her discomfort, her sickness and her headache. But it all came back with the force of a truck, and she finally threw up, emptying her churning stomach out into the metal bucket. Jason held back her hair until she was finished.

'Ugh,' she groaned, leaning her head back against the wooden support.

'How long you been feeling ill for?' Jason asked, wrapping his arms around her shoulders. His fingers started to play with the braid laced with eagle feathers. Piper found the gesture quite comforting, and leaned her head against his shoulder.

'Since this morning,' she mumbled. 'I woke up and I felt awful. I feel sickly, and I have an awful headache.'

'No ambrosia? Might make your headache better.'

'I had some. No change.'

Jason bit his lip, like he was worried.

'What's wrong?'

'Pipes, your headache… Describe it.'

'Why?'

'Just do it, please.'

She sighed. 'It's like someone's digging into my head with a knife, getting worse and worse with each second.'

Jason's eyes went wide. He pulled his arm back and jumped to his feet, pulling Piper up with him, despite her protests. She set the bucket aside and turned to Jason with a glare, resting her hands on her hips. The pain in her head began to escalate quickly, getting to the point where she could not bear it.

'What is going on? What's wrong?' she demanded, trying her hardest to ignore the pain.

'Piper, I felt the same way when I was taken over by the eid - Pipes? Piper? What's wrong?'

Piper doubled over, a horrible pain growing from her stomach. Her head felt as if it was about to split. Her stomach felt as if it was being boiled. Then, all the pain vanished, all in an instant. Her mind went blank. All her thoughts just stopped. She straightened up, her eyes closed. When she opened them, Jason took a few staggering steps back.

They were gold.

Jason.

'Pipes?' he asked weakly, not daring to approach his girlfriend. 'Piper, you in there?'

'Not anymore,' she hissed. Jason winced. She didn't sound like Piper. She didn't have her normal playful, teasing, soft voice. Instead, her tone was cold and vicious. Jason gripped the hilt of his gladius tight, yet he hoped he would not have to fight with Piper. That would just make the nightmare worse than it already was.

'You promised,' he growled. 'You promised never to possess any other the members of the Argo II.'

'I made no such promised,' Piper sneered. Her own hand went for her knife and, with a blurry flick of her wrist; she drew the deadly golden knife. 'Maybe another eidolon did, but I did not. I can do as I wish upon this ship.'

'No you can't,' Jason said. Reluctantly, he drew his blade, half-hoping that the fought of a fight would scare the eidolon out of Piper. 'Leave her body at once.'

'Or what, son of Jupiter?' Piper hissed, starting to circle him. Jason followed her moves, and the two of them paced around in a circle, each keeping the other in their line of sight. 'You can't hurt this body. You could never bring yourself to.'

'Who says I couldn't?' Jason said. He tried to keep the fear from his voice. He himself knew full well that he wouldn't hurt a hair on Piper's head.

'Please,' Piper scoffed. 'If this girl was holding a knife to your throat you wouldn't even dare to give her a miniscule paper cut with that letter opener of yours. My brethren told me so. They've been in your head. Seen the things you can do… And what you can't.'

Jason's hand trembled. The gold of his sword quivered. He forced himself to keep a straight face and to betray no emotion, just as he was taught back at Camp Jupiter. He steeled himself for the fight he knew would be coming his way.

'Stand down, Jason Grace,' Piper said, 'And I'll promise you a quick death.'

'No chance.'

'So be it.'

Piper leapt at him. He brought his sword upwards, and a loud clang! rang through the air. Sparks flew as the bronze metal of Piper's knife and the gold surface of Jason's sword met with enough force to make Jason stagger backwards slightly. Piper advanced towards him, slicing her knife this way and that, stabbing at him, trying to land a hit. No such luck for the daughter of Aphrodite, however.

Jason hated himself for doing so, but he aimed a kick at Piper's gut and sent her flying into the mast of the ship. Piper snarled, blew her hair out of her face and threw herself at Jason. A well-aimed kick knocked Jason's gladius from his hand. The weapons fell to the deck with a loud clattering sound that would hopefully alert the others. A second later, Piper barrelled into Jason and knocked him flat.

The two of them rolled into a pile of crates. One fell down and caught Piper's head. The corner of the crate split the skin above her left eye and she cried out.

'Ow!' she shouted, and, for just a second, her voice was her own, not the horrible cold voice of the eidolon.

'Pipes!' Jason shouted, rolling so that he was on all fours. Piper had fallen back, her hand trying to stem the flow of blood from her cut. A vicious snarl escaped her lips and she charged again. Jason groaned. His Piper was gone again. He needed to get the eidolon out of her head.

His temporary distraction allowed Piper to get to close. There was a flash of bronze, a light shining in Jason's eyes, and then a sudden, immense pain that made him scream out in pain. Piper laughed, a high pitched, insane laugh that was not her own. Jason fell to his knees, Katoptris, Piper's knife, buried to the hilt in his shoulder. Piper gripped the hilt and pulled it out. Jason nearly passed out from the pain.

Piper stood over him, ready to deliver the last blow. Quick as a flash, Jason moved his weight onto the toes of his left foot, braced his hands on the wooden deck and span around, using his right leg to knock Piper's legs from beneath. She fell down onto the deck and Jason jumped on top of her, pinning her down by her shoulders.

'Get out of her now!' he snarled. Piper snarled and spat in his face. Her hands came up, and she dug her fingers into the fresh, deep wound in Jason's shoulder. The son of Jupiter doubted he'd ever screamed so loudly. Piper grinned, pulled her bloodied hand back and punched Jason's mouth. He fell backwards and she leapt at him again. He was ready for it, however. He grabbed the material of her jacket collar and shoved her down onto the deck. Her head hit the deck with a dull thud. Her eyes turned back to their normal kaleidoscope state, before they rolled back in her head. Her body went limp, and Jason fell back, clutching his shoulder.

His breath came out in pants. The moonlight made his sweaty skin gleam slightly. He snurched once, wiped his face on the sleeve of his windbreaker and staggered to his feet just as the other four ran up onto the deck.

'What was the screaming for?' Hazel asked. Her eyes took in Piper's unconscious form on the deck, Jason's wounds and the blood on the deck. Leo was smouldering. Clearly, he'd set himself on fire. Nico's sword was drawn, and he looked ready for a fight.

'What happened?' Frank asked, kneeling beside Piper and resting a hand on her forehead. Jason clutched at the wound on his shoulder, the bleeding worse than ever.

'You don't want to know,' was all he said.