He fell to his knees heaving for breath, collapsing to one side as bloodstains spread over his shirt. His head was pounding something awful, and he felt shaky and heavy, his heart hammering loudly in his chest. Distantly, he could hear people yelling his name, but he was already slipping into unconsciousness. Blonde hair and wide grey eyes filled his darkening vision before his body went limp, succumbing to sleep.

"Percy! Percy, by the Gods, no! Stay awake you idiot!" Annabeth cursed as she pulled his head into her lap and ran her hands over his torso, checking for broken bones. He had some shallow slices down his chest and a longer cut curling from his shoulder to his waist, but the blood was clotting. One of his ribs on the left side gave slightly when she pressed on it. Cracked then, she deduced. A symptom of being thrown into a wall, she mused, carefully wiping blood from his head wound.

"Annabeth! Is he okay?" Hazel worried her bottom lip, frowning down at the son of Poseidon. Frank put an arm around her comfortingly. Annabeth nodded, scanning them both for injuries she found only scratches, bruises, and monster dust.

"It's a lot of blood but his wounds aren't too bad, it's his head I'm worried about" she trailed off as Jason, Piper, and Leo rounded the corner, yelling. Typical, she thought, what now.

"Whoa! What happened to you guys?" Jason asked, he had a large gash on his arm and there were purpling bruises forming on his jaw. Piper and Leo were covered in, ew, what looked to be black blood? Tar? Marmite? Whatever it was, neither looked happy about it. Piper also had three claw marks cutting through her blue jeans into her thigh.

"Big ugly monster, had a grudge against Poseidon," Annabeth motioned to Percy "what about you?"

"About the same, is he okay?"

"He's hurt, but he should be fine with some ambrosia. Did you find a way out of here?" Annabeth gently brushed a lock of Percy's ebony hair away from his face.

Jason answered, "No, unfortunately. This place is like a maze and a lot of the tunnels are either sealed up dead ends, barred, or underwater. I think this used to be an aqueduct or something? There are pipes and floodgates everywhere."

"What about the way we came?"

"It's now underwater," Leo answered, frowning uncomfortably at the fact, and Annabeth sympathized. Hundreds of feet underground with no way out and no way of navigating. Gods, it was like the Labyrinth all over again.

"Hades. But-" a loud rumbling interrupted Annabeth. She looked around for its source as the others slipped into defensive stances around her and Percy. It got louder, a distant roaring filling the circular chamber. Suddenly the exits surrounding them slammed shut, metal doors locking.

"What's happening!" Hazel clutched her sword.

"Oh no," Piper paled, "aqueducts.." Annabeth caught on immediately, cursing their luck. The roaring suddenly made sense. Water. There was a flood of water heading their way as the flow was redirected through the tunnels. The exits shut to contain it in this room. One way in, no way out. Unless...

"Wait! What's happening?" Asked Frank

"We're all gonna drown! This chamber is gonna fill up with water and we're all gonna die! Great! Just how I wanted to die! Slow and painful!" panic leaked through Leo's sarcasm.

The others all started yelling over one another,. Annabeth looked for options, the chamber was only two stories, too low for Jason or Frank to fly, and the walls and doors too solid for Leo to blow through without hurting them in the process. Annabeth's mind whirred through plan after plan, dismissing them all in seconds.

Unbeknownst to the others in their panic, Percy stirred, eyes cracking open as the world spun lazily around him. Sound filtered in, a familiar thundering filling his ears and Percy, dazed from his head injury and blood loss, tried to sit up. Only managing to roll out of Annabeth's lap, he landed on his hands and managed to get one knee under him, pushing himself vertical. The movement had garnered the others' attention, the shouting ceasing some as he unsteadily rose to his feet. Annabeth reached out a hand to steady him but he shook his head, wincing at the motion.

"Get behind me" Percy's voice was rough, but heard clearly over the approaching roar of floodwater. The other demigods complied hastily.

Just then the white wall of water came surging towards them, bursting from the tunnel with deafening speed and deadly eagerness, the maelstrom ready to crash into them. Percy spread his feet shoulder-width apart, knees bent, arms outstretched before him. His bloodstained orange shirt was in tatters, old scars and new wounds peeking through the rips. A look of scarily intense concentration on his face as the others held their breath. The water crashed against an invisible barrier a few feet away from Percy, frothing and powerful as an angry sea. It flooded up and around them in a half sphere. The deluge continued to pound into the room, rapid and relentless. The demigods' breath catching at the dramatic display before them, as Percy controlled the flow of thousands upon thousands of gallons of water. A doorway somewhere behind them slammed open too, letting in a new torrent to rain down from the second story. Percy shakily dropped to one knee, wavering slightly for a moment,. His arms shook at the strain, vision darkening as the world lurched. But he pushed back against it, concussion or not he was still the son of the sea god. Dark head lowered and mussed hair falling into his eyes, the tug in his gut painful, he centered his power. Underwater waves licked at the perimeter of their bubble of safety. Wave after wave flowed around them, until finally the chamber seemed to have filled completely. Percy twisted to one side, falling into a sitting position and wiping his face of sweat and blood wearily, grimacing. The others stared at him with wide eyes. His own eyes seemed to be glowing an ethereal emerald in the wavering underwater shadows. The water making up the dome of air continued to ebb and swell jaggedly, like waves on a stormy lake. Noticing this, Percy took a deep shuddering breath, wincing and holding a hand to his injured side as the water smoothed out, allowing them to view their surroundings more clearly.

"Woah" Frank muttered, the adrenaline rush from almost dying again left his hands shaking.

"Uh, seconded… you okay, Percy? Thanks for the save by the way." Jason glanced warily at the walls of water surrounding them, equal parts amazed and terrified.

"No problem, and I'm fine, thanks. But I can't hold this forever, and I don't think you guys want to start a new life underwater. So what's the plan?" He turned to Annabeth and Piper, who seemed the least freaked out. Percy absentmindedly contemplated using some of the water to heal himself but decided against it. Irritating and painful as his injuries were, he needed his strength to keep everyone else from drowning. Priorities, he mentally huffed.

"We couldn't find a way out of here," Piper explained, pausing to hit Leo upside the head as he stuck his entire arm in the water wall in wonder. Percy absentmindedly tapped Leo to dry him off as Piper continued, smirking slightly as Leo did a triple take, "And a lot of the exits were blocked or underwater. How long can you keep this up?"

Percy paused to think about it, "If it were just me, indefinitely, but with six of you that's a lot of air to cycle so we don't run out of oxygen" Jason and Frank blanched, having not even thought of that as an option. Annabeth had that look on her face where she wanted to ask questions but was stopping herself. "So probably a couple hours, maybe more. But I think I can find a way out of here. Give me a second… " Percy trailed off as he closed his eyes.

He reached out with all his senses, ignoring the pain and focusing on the tugging in his gut, following it. His perception of the water expanding, he could feel the liquid surrounding them, flowing through pipes and plumbing, tubing and tunnels branching out all around him. He could feel rainwater puddles far above them, and the condensation on a metal door three chambers away, he could even faintly sense the water in the bodies of his friends, but he quickly shifted his focus, shuddering. He narrowed his search to the larger tunnels, connecting them through a series of turns, feeling which tunnels had obstacles and adjusting his mental path. There, he felt, the water led out into a larger lake close on the surface. Percy pulled his awareness back to his friends.

"I found a way out. It's completely underwater, but I think I can move this air bubble with all of you inside. The exit leads into the ocean, where I can bring us to shore. But that's all going to take a lot of my energy, so we need to move now. Unless anyone has a better plan?"

Annabeth furrowed her eyebrows slightly, analyzing. Jason and Piper shared a look, Frank and Leo shrugged, and Hazel only crossed her arms anxiously. Percy understood, they were in one of the Big Three's domain, with no way to leave except through.

Annabeth shook her head at him, "let's go then," she sighed.

"My dad won't hurt any of you guys while I'm here, don't worry." Percy flashed a grim smile at Hazel and Jason especially. "Okay, so because we've got to move fast, I'm not gonna pull a Moses, instead we're gonna straight up torpedo outta here."

"WHAT"

"So buckle up buttercups,'

"WAIT, uh Percy! AHH!" They all stumbled, falling into a tangled pile as Percy made the water beneath them denser, forming a bubble of air and dense water around them.

"Please keep your arms and legs inside the ride at all times, thank you." And with that, Percy stepped through the bubble into the water. Hazel shrieked.

His hair floated gently underwater, and some of his drying blood stained the water. Bright green eyes flashing, he made calming gestures with his hands before propelling himself to the entrance of the tunnel using the current around him. The others just stared, their expressions ranging from awe to irritation. (Take a guess at who was who)

"We're going to regret this aren't we." Piper deadpanned, untangling her leg from underneath Hazel.

"If we live to regret this. But, yeah. I'm regretting it right now. And nothing's even happened yet" Leo threw up his hands, hitting an already glaring Jason in the face.

"Story of my life" Annabeth rolled her eyes.

Percy suddenly moved forward, slicing quickly through the water like a shark, after putting a few feet between us, our safety snow globe lurched forward after him, like a subway train jerked into motion. Which was fine, once they got used to floating down an underwater tunnel in a giant bubble at forty miles per hour, it really wasn't too bad. Until Percy sharply turned a corner, glancing back at the bubble with a smirk.

"OH COME ON!"

"DON'T YOU DARE THROW UP FRANK!"