Chapter 1: The Cold Calculus.
The first thing Marco Seika felt when he woke up was a deep, cellular deficit.
It wasn't ordinary hunger. It was the demand of a biological furnace that burned cold, consuming calories to maintain a state of near-perfect homeostasis. His body had spent the night repairing the micro-tears in his muscle fibers from yesterday's conditioning.
He sat up in the pre-dawn light of Musutafu. He moved through his morning routine with practiced efficiency. There were no wasted movements. He sat on the edge of his bed, closing his eyes for a moment of absolute stillness. He visualized the blue flame dormant in his marrow, checking his internal state like a pilot checking instruments before a flight. Control. Discipline. These were the only things keeping the ravenous hunger in check.
Breakfast was a calculated intake. Six eggs. Two large bowls of rice. Four slices of pineapple. He didn't eat for taste; he ate to refill a fuel tank. His Quirk, Phoenix, was a supreme defensive mechanism, but its engine required immense resources.
He pulled on the stiff black uniform of Aldera Junior High. He checked himself in the mirror. His expression was placid, his eyes calm. He wasn't lethargic; he was efficient. Why waste energy on unnecessary emotions?
"Another day," he whispered, conserving his breath.
The classroom at Aldera Junior High was a noisy container of adolescent egos.
Marco sat in the back, his presence unobtrusive. To his right, Izuku Midoriya was shrinking into his notebook, radiating anxiety. To his left, Katsuki Bakugo sat with his feet up, the undisputed tyrant of this small pond.
The teacher's announcement about U.A. High acted as a catalyst.
"Hey, teach!" Bakugo silenced the class. "Don't lump me in with these extras. I'm the only one going to U.A."
The teacher checked his list. "Oh, Midoriya wants to try for U.A., too. And... Seika."
The resulting explosion was predictable. Bakugo slammed his hand onto Midoriya's desk.
"DEKU!" Bakugo roared, smoke curling from his palms. "You Quirkless loser! You think you can compete with me?"
Midoriya scrambled backward, terrified. "Kacchan, wait! I'm just trying—"
"Shut up!" Bakugo raised a hand, sparks crackling threateningly close to Midoriya's face.
Marco didn't sigh. He didn't get angry. He simply made a calculation.
Bakugo's ignition point is low. A direct hit on Midoriya will result in second-degree burns and potential auditory damage. Midoriya has zero damage mitigation.
Marco closed his book quietly and stood up. He walked over the few feet separating them. He didn't posture or threaten. He just stepped in between the bully and the victim, facing Bakugo.
"Move, Feathers," Bakugo snarled. "Unless you want to get scorched."
Marco looked at him calmly. "You're wasting energy, Bakugo."
That was enough. Bakugo, insulted by the indifference, swung his right arm. It was a reflex action, a point-blank explosion aimed directly at Marco's face.
BOOM.
The sound was deafening in the small room. Smoke billowed, acrid and hot. Midoriya yelped.
When the smoke cleared, the class gasped.
The left side of Marco's face was heavily damaged. The skin was charred black, blistered and raw from the intense heat of the nitroglycerin blast. Smoke rose gently from his cheek.
But Marco didn't flinch. He didn't cry out.
Almost instantly, a soft, azure light manifested.
Hiss...
It wasn't the sound of burning, but the sound of rapid cooling. Beautiful, cold blue flames danced over the injury. They didn't radiate heat; they absorbed it. The flames flowed like water over the charred tissue. In seconds, the dead skin flaked away like grey ash, revealing pristine, unblemished flesh underneath.
The regeneration was complete. The only sign there had been an injury was the slight lingering steam.
Marco blinked, his face perfectly restored. He felt the sudden drain on his stamina reserves—the breakfast eggs burned away in a flash of blue light.
"Are you satisfied?" Marco asked Bakugo, his tone flat.
Bakugo stepped back, his eyes wide with a mixture of fury and revulsion. "You freak... You just stood there."
"It was the logical choice," Marco said simply. "I heal instantly. Izuku does not. Why should he take permanent damage when I can take temporary damage?"
Bakugo ground his teeth. He hated this. He hated that his greatest weapon, his ability to inflict pain and fear, was completely nullified by Marco's biology. Hitting Marco was like punching water; it just reformed, indifferent to his effort.
"You coward," Bakugo spat, turning away. "You'll never be a hero. You're just a regenerating meat shield."
Marco didn't respond. He turned and offered a hand to Midoriya, pulling the trembling boy to his feet.
The walk home was quiet as the sun set.
"Marco-kun..." Midoriya looked at Marco's flawless profile, still unable to comprehend what he had seen. "Thank you. But... didn't that hurt?"
"The heat destroyed the nerve endings on impact," Marco explained clinically, opening a high-protein energy bar he'd bought from a vending machine. "The blue flame cools the area immediately as it reconstructs the tissue. There is very little pain. Just exhaustion."
He took a bite of the bar, chewing slowly.
"But still," Midoriya mumbled, clutching his backpack straps. "You stood in front of Kacchan's explosion. That's... that's what a hero does."
Marco stopped walking. He looked at the horizon.
"It's not heroism, Izuku. It's calculus," Marco stated firmly. "In a situation with unavoidable damage, you mitigate the consequences. My body is built to mitigate damage. Yours is not. It was the only rational decision."
He finished the bar and crumpled the wrapper.
"Go home, Izuku. Study for the exams."
Marco watched him go, then turned towards his own house. He felt heavy. The regeneration had cost him. He needed dinner. He needed rest.
He wasn't trying to be a savior. He was just applying the cold logic of his existence to a chaotic world. If he could endure what others couldn't, then logic dictated that he should.
It was as simple as that.