I Was Trapped On My Sub With My Rival—Then He Got A Fever Only I Could Cure

The first shudder was violent enough to send a rack of medical texts crashing to the floor of the control room. Law, who had been charting their course through the squall, braced himself against the console, his knuckles white. A long, metallic groan echoed through the hull, a sound like a dying beast, and then… silence. The steady, familiar hum of the engine was gone, replaced by the muffled roar of the storm outside and the unsettling creak of the submarine settling in the turbulent water.

"Shishishi! That was a big bump!"

Law’s jaw tightened. He turned to see Luffy picking himself up from the floor where he’d been napping, a wide, unconcerned grin splitting his face. The Straw Hat captain dusted off his shorts as if being tossed across the room was a minor inconvenience, a fun part of the ride.

"The engine has failed, Straw Hat-ya," Law said, his voice a low, controlled monotone that did nothing to betray the cold spike of fury twisting in his gut. He pushed off the console and strode towards the corridor leading to the aft of the sub, his long coat sweeping behind him. Of all the times for Bepo and the others to be on a supply run. Of all the times to be stuck in the deep with this man.

"Oh? Can you fix it?" Luffy asked, trotting behind him like an overgrown puppy, his sandals slapping against the metal decking.

"I am a doctor, not a mechanic," Law clipped out, not breaking his stride. It was a lie, of course. He knew every bolt and wire of his submarine. He had to. He trusted no one else with its maintenance.

The engine room was stifling, the air thick with the smell of ozone and burnt metal. Law’s practiced eyes swept over the massive, inert machinery. He ran a gloved hand over a coolant pipe—cold. He checked the primary power coupling—fused. A cascade of failures, all stemming from a single critical fracture in the main turbine. A fracture that could not be welded, not with the tools he had on board. They would need a custom-forged replacement part. They were, for all intents and purposes, dead in the water.

His frustration was a physical thing, a pressure building behind his sternum. He had planned for every contingency, every battle, every strategic retreat. But he hadn't planned for this. Stranded. Miles from any known shipping lane. Alone with the one variable in his life he could never, ever account for.

"So, is it broken?" Luffy asked again, peering over Law's shoulder, his proximity an unwelcome source of heat in the already sweltering room.

Law took a slow, deliberate breath, forcing the anger down. "Yes, Straw Hat-ya. It is broken."

"Don't worry, Traffy!" Luffy clapped him hard on the back, nearly sending him stumbling into the useless engine. "Something will work out! I'm getting hungry. You got any meat?"

Law gritted his teeth, the imprint of Luffy's hand still stinging on his coat. Meat. Of course, that was his primary concern. Not the fact that they were stranded in a metal coffin at the bottom of a hostile sea. He shoved past the other captain without a word, his long strides eating up the narrow corridor towards the galley. If feeding the idiot would grant him five minutes of silence, it was a small price to pay.

The Polar Tang was not built for two captains, especially when one of them had the spatial awareness of a cannonball. Luffy trailed him, his presence a constant, vibrating energy at Law's back. He seemed to fill the entire hallway, his limbs flailing as he peered into every room they passed.

"Ooh, what's in here?" Luffy darted into Law's personal study before Law could stop him. It was a small, meticulously organized room lined with medical texts and anatomical charts. His space. His sanctuary.

"Do not touch anything," Law warned, his voice dangerously low as he stood in the doorway, blocking the exit.

The warning was as effective as whispering at a hurricane. Luffy was already pulling a heavy leather-bound book from the shelf, its gold-leaf title glinting in the low light. Advanced Surgical Pathology. He flipped it open, his eyes wide. "Whoa! Look at all the gross pictures! Is this what people look like on the inside?"

"That is a medical textbook, Straw Hat-ya. It is not a picture book for your amusement." Law's patience was a thread, stretching thinner with every second Luffy spent defiling his library.

Luffy ignored him, pointing at a detailed diagram of the human circulatory system. "So you can really take out people's hearts? Like you did at Punk Hazard? How do you do it? Do you use a special knife?" His questions came in a rapid-fire burst, devoid of any malice, just pure, unfiltered curiosity. He turned, the book still open, and took a step closer to Law, closing the already negligible distance between them. Law could feel the warmth radiating from him, smell the faint, clean scent of sea salt that always clung to his skin.

"I use my Devil Fruit ability," Law stated, his tone flat and cold. He refused to step back, to cede any more ground. "And if you don't get out of my study, I will give you a live demonstration."

Luffy just laughed, a loud, booming sound that was entirely too big for the small room. "Shishishi! You're always so serious, Traffy!" He slapped the book shut, a cloud of dust puffing into the air, and shoved it back onto the shelf with no regard for the proper order. "Okay, okay! I'm still hungry, though. Let's go find that meat!"

He bounded out of the study, clapping Law on the shoulder again as he passed. The touch was casual, friendly, and it made Law's skin crawl with an irritation so profound it was almost a physical ache. He was a cornered animal, and the cage was shrinking by the minute.

Hours later, the oppressive heat of the engine room had only intensified. Law had stripped off his coat, leaving him in his black t-shirt, which was already damp with sweat and sticking to his skin. He knelt before an open access panel, a multi-tool in one hand as he meticulously worked on rerouting a secondary power conduit. It was a long shot, a desperate attempt to restore at least minimal functionality to the sub’s life support and navigation systems. Behind him, Luffy was holding a battery-powered work lamp, his usual chaotic energy subdued into a rare, focused silence. He hadn’t said a word in nearly ten minutes, a record Law was grimly appreciative of.

The air was thick with the smell of hot metal and lubricant. Sweat dripped from Law’s temple, and he swiped it away with the back of his wrist, never taking his eyes off the cluster of wires. He reached out a hand without looking. "Screwdriver. Phillips head."

A moment later, the cool, plastic handle of the tool was pressed into his palm. He took it, surprised by the promptness. Maybe the gravity of their situation was finally sinking into Straw Hat-ya's thick skull. He tightened a terminal screw, his fingers moving with practiced precision. Just one more connection to bypass the fried circuit. He could feel the proximity of Luffy’s body behind him, a solid wall of warmth that was distinct from the ambient temperature of the room.

He was about to ask for the wire strippers when the work lamp in Luffy’s hand flickered once. The low hum of the emergency power converters faltered.

Then, everything went out.

The darkness was absolute, a sudden, suffocating blanket that swallowed the light and sound. The hum died, the lamp went dark, and even the distant groan of the hull seemed to be muffled. Law froze, his hand still outstretched, the screwdriver clutched in his fingers. The silence that rushed in was profound, broken only by the faint, rhythmic rush of his own blood in his ears and another, softer sound.

Breathing.

It was right beside his ear. Steady. Unhurried. Luffy hadn't moved. He hadn't yelled or panicked. He was just there, in the pitch-black, breathing with a calmness that was utterly unnerving. Law held his own breath, listening. He could feel the heat from Luffy’s shoulder, less than an inch from his own. He could smell the faint scent of rubber and sea salt that clung to the other man.

In the void, stripped of sight, his other senses sharpened to a painful degree. The irritation that had been simmering in him all day vanished, replaced by a strange, hyper-awareness of the man next to him. He was aware of the subtle shift of fabric as Luffy adjusted his stance. He was aware of the sheer physical space Luffy occupied, the solid presence of him in the shared dark. It wasn’t a strategic awareness, not the way he assessed an enemy on the battlefield. This was different. It was a primal, unwelcome recognition of another living body, warm and breathing, sharing his air in the suffocating confines of the dead submarine. The slow, even cadence of Luffy’s breaths felt impossibly loud, an anchor in the disorienting blackness, and for a terrifying moment, Law found himself unconsciously trying to match it.