Frank woke up underwater, in a greenish-blue cave lit by moss. He was floating gently, but didn't know how he was breathing or why his clothes didn't feel wet. He looked around, and saw that Hazel and Leo were here too, though Leo was asleep.

'Where are we?' He asked Hazel.

'Dunno.' She said glumly. 'Somewhere under the sea. We fell here after the sea monster attacked, but i guess something here saved us.'

Frank remembered the events that led to this. What coach Hedge said about Leo and Hazel staring into each other's eyes and holding hands, then the giant shrimp monster knocked them overboard.

'Hazel...' He asked. 'What were you and Leo doing when the monster attacked?'

'He was just...' Hazel began, but seemed to hesitate. 'Never mind. But we need to talk.'

'Okay...' Frank said, 'What about?'

She stared at him for a moment.

'Did you have sex with Annabeth or Piper?'

Frank winced nervously.

'Yeah... Because of the whole Eidolon thing, remember?'

'No.' Hazel stopped him. 'I mean alone. Without me.'

'Yeah, with Annabeth, before we got to Charleston.' He confessed. 'Look, I'm sorry, I know we're dating and-'

'It's okay.' Hazel interrupted

'What?' Frank wondered. 'You're not mad?'

'I had sex with Annabeth too.'

'Oh.' Frank finally said.

'Frank,' Hazel prepared herself to ask. 'Do you... Do you want to maybe keep going?'

'What do you mean?'

'Annabeth told me once that demigods can't ever stay with one person, at least sexually. It's part of the godly genetics.' Hazel took a deep breath. 'I'm finding it so hard to fight that, I'm sure you are too. On the way to Alaska, we had sex with the amazons, goddesses, and nymphs behind the other's back. Even back in camp Jupiter, you and I both fucked Reyna alone. Can we just stop fighting it? Not care about what we do with other people and just do what we want to?'

Frank looked down at his hands.

'That felt really nice to hear.' He said quietly.

'Wasn't it?' Hazel said, relieved. 'I was really worried you wouldn't like it. I thought it would ruin our relationship.'

'It's still weird though, right?' Frank sighed.

'You'll just have to put a lot of effort on your part to convince me that you love me more than any other girl.' Hazel said, smiling.

'You mean like this?' Frank said, as he tore off Hazel's blouse seductively.

'Hmmm...' Hazel gleamed. 'I'm not convinced yet.'

'Look's like I'll have to try harder.' Frank whispered, then pulled her head to his and kissed her. Hazel returned the kiss, and soon they were passionately making out, completely ignoring Leo, still asleep in the corner of the cave.

Soon, the couple found themselves naked in the middle of the cave, getting it on. Hazel was on top, and she reached between their bodies to stroke Frank's cock. Frank's hands went to Hazel's breasts, squeezing them gently. Hazel gasped, and arched her back slightly, grinding her hips against Frank's legs.

'Ohhhh...' Hazel moaned. 'That feels so good.'

'Are you convinced now?' Frank asked.

'Oh, yeah.' Hazel nodded. 'This is perfect.'

Frank leaned down and kissed Hazel again. Hazel responded by sucking his tongue into her mouth.

'You taste so good...' Hazel moaned.

Frank rolled over on top of Hazel, and held her hands on top of her head with his. He moved free hand from Hazel's tits, to her thighs, then slowly to her pussy. Hazel let out a moan, and her legs wrapped around Frank's waist. Frank pressed his finger into Hazel's pussy, sliding it in and out. Hazel squirmed slightly, enjoying the sensation.

'Ohhh...' Hazel moaned. 'It feels so good...'

She lowered herself down onto Frank's dick, sliding all the way down. She could feel it pressing against her cervix.

'Fuck, you're so tight...' Frank groaned. 'You're so tight!'

He started thrusting in and out

'OHH GODS!' Hazel began to scream.

Frank's pace increased, and Hazel felt the orgasm approaching. She arched her back and closed her eyes, letting out a moan. Frank started thrusting faster and faster. Soon, she started coming, her body shaking uncontrollably. Her orgasm lasted for a few minutes, until Frank pushed himself as far as he could into her, sending her into another climax. They floated in the water, panting and sweating, completely spent.

'That was... Amazing.' Hazel said, wiping sweat off her face.

'Mmm...' Frank agreed.

'I'm so happy we decided to do this.'

'Yeah...' Frank smiled. 'Me too.'

A/N

Next up is a Percy/Piper/Annabeth threesome

If you a pairing you want to suggest, review it! I'll see if I can fit it into a later chapter in the story.