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A Mortal Sun

Summary:

What if everything we thought we knew about Lex Luthor’s hatred for Superman was wrong? What if it wasn’t blind, and it wasn’t about alien powers or threats to Earth—but about someone… very personal?

Harrison Luthor, a soul reincarnated from another life, suffers from a debilitating meta-ability triggered by a fragment of alien debris during one of Superman’s early battles. Lex will stop at nothing to save his brother, throwing the weight of LexCorp and his genius into a desperate search for a cure.

When Harrison encounters Clark Kent, a mild-mannered reporter, he finds a connection that awakens a sense of belonging he hasn’t felt since his last life. But Clark harbors a dangerous secret: he is Superman. As their bond deepens, Lex must confront a painful truth: the cure may lie in the hands of the man he has sworn to destroy. Loyalties, love, and vengeance collide as the brothers—and Harrison’s heart—face choices that could change their world forever.

Chapter 1: The Ache of Echoes

Summary:

Harrison Luthor’s body betrays him with a violent, glowing flare of his latent powers. As Lex fights to save his brother, memories of a childhood accident and a stray piece of alien debris reveal the true, personal reason behind Lex’s hatred for Superman—and the unbreakable bond that will define them both.

Chapter Text

Harrison Luthor’s world was a symphony of pain. It began with a whisper, a low hum in the marrow of his bones that he had learned to recognize as a death knell, a prelude to the violent crescendo. It was a cold, alien ache, unlike anything a normal human body should ever feel. He was accustomed to it—he had been a ghost in his own flesh for as long as he could remember—but the crescendo was what he dreaded.

It started with a warmth, a sudden heat that bloomed beneath his skin like a burning flower. Then, the glow. First in his fingertips, a faint, sickly green light that pulsed with the beat of his heart. It was beautiful, in a terrifying, grotesque way. It spread up his arms, a spiderweb of emerald veins visible just beneath his skin, and then across his chest, a luminescent pattern of ancient, impossible runes. The pain was no longer a hum; it was a shriek. A thousand needles, hot and sharp, piercing his every nerve. His muscles spasmed, his teeth clenched so hard he thought his jaw would shatter.

“Harrison!”

Lex’s voice was the only thing that could ever cut through the noise. It was not the cold, controlled baritone of Lex Luthor, CEO and public figure, but the raw, frantic sound of a terrified older brother. It was a sound Harrison cherished, a reminder that in this second life, he was not alone.

Lex was at his side in a second, his hands, so often gloved in polished leather or clasped behind his back, now held Harrison's face, his thumb stroking a frantic line across his cheek. “The sedative. Now!” he bellowed to the med-droids.

Harrison’s vision swam, his perception of the meticulously clean, sterile lab blurring into a watercolor of white, steel-gray, and the horrifying, neon-green of his own body. He felt a phantom weight on his chest, a heavy, suffocating sensation that had nothing to do with the present. The pain from the Echo was a tidal wave, pulling him under and back, not just in space, but in time.

 


 

Metropolis, thirteen years ago.

The air in the LexCorp R&D lab was thick with the scent of ozone and heated metal. Nine-year-old Harrison sat curled on a stool, a sketchpad in his lap, drawing a fanciful dragon with three heads. He didn’t look up as his older brother, Lex, a severe-looking fifteen-year-old even then, paced furiously around a glowing containment field.

Lex had been distant since their parents’ death. Colder. He had always been brilliant, but now his genius had a frantic edge, a ruthless ambition that left little room for a quiet, sensitive younger brother. He tolerated Harrison's presence, but rarely acknowledged it.

Harrison, however, was persistent. It was his nature. He wanted to love his brother, to be loved by him, no matter how cold Lex was. Every day, he would ask about Lex's projects, bring him a glass of water he hadn't asked for, or simply sit in the same room, a quiet, loving presence.

“Maybe the thermal regulators are off by a few degrees, Lex? It looks a little stressed,” Harrison said, his voice small but clear. He had noticed a flicker of light, an irregularity in the humming device that Lex hadn't seen.

Lex stopped pacing. He stared at Harrison as if he were a particularly irritating insect. “Did you just give me a diagnosis?”

“I-I just… it looks like it’s struggling,” Harrison stammered, shrinking a little. He felt Lex’s disapproval like a physical blow.

Lex just scoffed and turned back to his console, muttering, “What would you know?”

The next few minutes were a blur. A warning siren blared, a jarring, electronic scream that cut through the silence. The blue light in the core pulsed faster, brighter.

“Lex, it’s not right!” Harrison cried, scrambling off his stool.

Lex, ignoring the alarms, was furiously typing commands into the console. “It’s fine! The containment field can handle it.”

But it couldn't. With a shriek of tortured metal, the containment field buckled, and the fusion core went critical. The blue light pulsed once, twice, and then a brilliant, searing wave of energy shot out, aimed directly at Lex.

Time seemed to slow to a crawl. Harrison saw his brother’s face—not the face of the brilliant genius, but the face of a terrified, vulnerable child. He saw the flash of the incoming energy and something inside him snapped. It was not a thought. It was an instinct. A raw, unthinking reflex from a life he didn’t remember, from a body that was more than just flesh and blood. He pushed. Not with his hands, but with something else. Something deep inside his core, something that hummed and pulsed with a kind of power that defied physics.

An invisible shield, a transparent dome of pure, unadulterated magical force, sprang into existence around Lex. It was a perfect, protective bubble. The wave of energy hit the shield with the force of a nuclear detonation, but the shield held. It glowed a brilliant, emerald green for a single, excruciating second, and then the energy dissipated into a cloud of sizzling, harmless motes. The shield flickered and vanished, leaving behind nothing but the stench of burnt wiring and a stunned, silent silence.

Lex’s eyes were wide, fixed on the empty space where the energy wave had been. His gaze slowly shifted from there to Harrison, who stood trembling, his hand outstretched, his body glowing with a faint, green luminescence that was not from the lab. He was a boy, no more than a child, but for one brief, impossible second, he had been a god.

Lex stared at him, and for the first time in months, his cold facade crumbled. He fell to his knees, not in fear, but in a kind of raw, overwhelming awe. “Harrison… what was that?” he whispered.

“I… I don’t know,” Harrison said, his voice shaking. “I was just… worried about you. I couldn’t let you get hurt.”

Lex stood, his brilliant mind racing. He reached out and touched Harrison’s face, his hand gentle, almost reverent. He had always known Harrison was different, had always loved him in a distant, intellectual way. But in this moment, a new, fiercer kind of love was born. He didn't see a boy with a strange power. He saw a lifeline, a reason to live, a reason to be more than just a genius. He saw a soul who would run into danger for him without a second thought, and he vowed he would spend the rest of his life protecting him from that same danger.

 


Metropolis, twelve years ago.

The day the world changed was a Tuesday. Harrison Luthor, a boy of ten, was in the family's private penthouse on the top floor of what would one day become the LexCorp tower. He was at a console, playing a simple flight simulator, the kind Lex had built for him from scratch, when a tremor shook the building. It was not a natural quake. It was a ripple in reality, a tear in the fabric of what they knew as normal.

Lex had just stepped out of the room to retrieve a fresh coffee. From the doorway, he saw his brother, and then, a piece of something else—a piece of the robot, a jagged, serrated piece of metal, hurtled through the air, aimed directly at the penthouse. It was a stray, a piece of a cosmic fight that had no business being there. But it was.

Lex froze. He watched, a horrified spectator, as a flash of red and blue streaked across the sky below, too fast for the human eye to track. The flash was a blur of chaos and destruction. And Harrison was standing, just standing there, with his back to the window, watching the city below.

“Harrison, get down!” he screamed.

But it was too late. The fragment of metal, alien and impossibly sharp, pierced the reinforced window and sliced through the room. Harrison, in his childlike innocence, just stood there, staring. It was a clean, precise strike. He felt a sharp, burning pain, and then a kind of numbness.

The piece of metal had hit him in the side, a glancing blow that would have been a mere cut for an adult, but for a child, it was a mortal wound. He fell to the floor, blood blooming across his white shirt, a dark crimson flower.

Lex was there in a second, his face pale with terror. He had seen the entire sequence. The flash of red and blue, the chaotic fight, the stray debris, the blood. It was all so quick, so senseless. His brilliant mind, his ruthless genius, was useless. He couldn’t save his brother.

As Lex knelt beside him, a raw, primal grief clawing at his throat, Harrison’s body began to glow. It was a faint, sickly green luminescence, pulsing with his frantic heartbeat. It was not a light of healing. It was a light of struggle, a silent, internal war. The pain from the wound was nothing compared to this new, violent ache. He didn’t understand it. He only knew that the light had been dormant inside him, a sleeping giant, and that the moment he was struck, the moment the alien energy entered his body, the giant had awakened.

Lex held his hand, his eyes wide with a mix of fear and helpless rage. He looked up at the window, at the sky where the flash of red and blue had disappeared. He saw not a hero, but a force of destruction, a being who had come to their world and, in his arrogance, had brought pain and suffering to the one person Lex loved most in the world.

“I’m sorry,” Harrison gasped, his voice a strained whisper, his eyes on his brother. He didn’t know why he was apologizing. He was just a child. But he knew, with a certainty that was as old as time itself, that this was his fault. That somehow, in another life, he had been a hero, a force of good, and he had failed.

Lex shook his head, a tear tracing a path down his cheek. “No, Harrison,” he whispered, his voice cracking. “Don’t you ever apologize. This wasn’t your fault. This was his. He brought this here. He did this to you.”

And in that moment, in the raw, aching silence of a child’s pain, the foundation of Lex Luthor’s hatred for Superman was laid. It was not a hatred born of arrogance, or jealousy, or a philosophical fear of alien power. It was born of a far simpler, far more terrible thing: love.

 


 

The memory faded, and the pain of the Echo washed back over Harrison, a cold, sharp blade. The med-droids had finally succeeded in injecting the sedative. The heavy, cold wave promised a temporary reprieve. The pain didn’t vanish, but it receded, softening from a shriek to a low, bearable ache. The emerald glow faded, and his muscles unclenched, leaving him trembling and weak. He sagged against Lex, who wrapped an arm around him, holding him with a fierce possessive grip that told the world he was not to be touched.

“I’m sorry,” Harrison murmured into the pristine fabric of his brother's suit. “I ruined the data again.”

Lex let out a shuddering breath, his body visibly relaxing as the crisis passed. He didn’t reply immediately, just held him, his head bowed, the familiar scent of his expensive cologne a comforting presence. When he finally spoke, his voice was low, raw with the effort of control. “Don’t you ever apologize for being in pain. You didn’t ask for this.”

It was this kind of quiet, unspoken kindness that made Lex bearable. The world saw him as a cold, calculating genius—and he was. But Harrison saw the man who had stayed up for three days straight, reviewing a hundred thousand scientific papers in a desperate search for a single, new lead. He saw the man who had personally designed the anti-rejection treatments, the man who had installed a hyperbaric chamber in his bedroom, and the man who, right now, was holding his trembling body as though it were the most precious thing in the universe.

The med-droids silently retreated, their diagnostics complete for the moment, leaving the brothers in the quiet of the lab. Rain lashed against the towering windows of LexCorp Tower, a gray curtain obscuring the sprawling cityscape of Metropolis below.

Lex gently guided Harrison to a cushioned bench, then turned to a massive bank of monitors. His expression hardened into the familiar mask of ruthless genius as he began to review the latest data. The monitors showed nothing but a series of erratic spikes, a meaningless scrawl of lines. He ran a diagnostic, and a cold voice from the computer confirmed his fear.

“System diagnostics complete. All data from the 11:03 p.m. event has been corrupted and overwritten by the subject's bio-signature.”

Lex slammed his fist on the console. The sound was a sharp crack in the silence. It was not a sound of rage, but of pure, unadulterated frustration. He had done everything. He had thrown billions of dollars at the problem. He had hired the top physicists, biologists, and neurologists. He had even, in his most desperate moments, consulted with occultists and mystics who promised him a cure in the realm of the unknown. And every time, the answer was the same. A brick wall.

“We’ve hit a wall, Harrison,” he said, his back to his brother. “A hard, impenetrable wall. The Echo… it’s a form of energy we can’t measure, we can’t contain. It’s like trying to catch starlight in a sieve.”

Harrison watched him, a familiar, hollow feeling settling in his chest. He knew this frustration, this despair. He felt it every day. But he had a different kind of understanding.

The Echo was not just a power, or a sickness. It was a memory. A scar from a life he didn't fully remember. Fragments would flicker at the edge of his consciousness, just out of reach. A flash of green light. A cackle that was both cruel and familiar. The feel of a thin, wooden stick in his hand, a feeling of innate, powerful control. And then, the hollow, vacant echo of something vast and terrible. A death he could not place. A name that was a curse.

This new life had been a blessing, a second chance. He had been reborn into a family—a broken, strange family, but a family nonetheless. He had a brother who would do anything for him, a brother who had wrapped his arms around him the first time the sickness hit and had never let go. And the Echo was the cruel price he had to pay. It was his past life's magic, trying to exist in a world where magic was not a natural law, where it was something alien and feared. The resulting conflict was slowly killing him.

“I’m not a sieve, Lex,” Harrison said quietly, his voice raspy. He knew his brother, knew how he was seeing this. Lex saw the sickness as a problem to be solved, a puzzle to be conquered. He was brilliant enough to conquer anything. But Harrison knew some puzzles weren’t meant to be solved.

Lex finally turned, his gaze intense and unwavering. “No. You’re not. You’re a vessel for a power that we, as a species, are not equipped to understand. We’ve exhausted every Earthly solution. We’ve tested every theory, every exotic material, every energy source. The answer isn’t here.”

His eyes narrowed, and a cold, dangerous glint entered them. Harrison knew that look. It was the look he wore when he was about to do something reckless, something the world would see as a political move, but which was, in reality, an act of sheer, unadulterated love.

“So we look elsewhere,” Lex said, his voice dropping to a low growl. He strode to the window, staring out at the rain-swept sky. A single, dark shape cut through the clouds, a streak of red and blue. The Superman.

Harrison watched his brother’s body tense, his hands clenching into fists at his sides. The hatred was a palpable thing, a force that seemed to push the very air out of the room. It was not a shallow, petty jealousy. It was born of a deeper, more primal place. It was born of a Tuesday twelve years ago when a boy lay bleeding on the floor. Lex saw the alien not as a god, but as a ghost—a ghost of the past that had stolen his brother’s life from him.

“He is a living library of alien knowledge,” Lex said, his voice a low, furious whisper. “He represents everything we need and everything we are denied. He claims to be for humanity, but he hoards a power that could cure you, a million pains.”

“He is not a monster, Lex,” Harrison said, his voice soft, full of a world-weary understanding. He had seen enough of those in his past life. This one felt different. He knew his brother saw him not as a hero, but as a cosmic curse.

“He is worse,” Lex snapped, turning to face him. “He is a coward. He came here with a knowledge that could save you, and he stood by while you suffered. I know his kind.”

Harrison knew he was talking about more than just Superman. Lex was talking about a deep-seated fear of power, of a force he could not control. But the fear was, for him, a secondary concern. The primary one was Harrison.

“What are you going to do?” Harrison asked, the thought a cold knot in his stomach.

Lex smiled again, a predator’s smile, full of a terrible kind of glee. “Then he’ll regret the day he ever landed on this planet.”

He put a hand on Harrison’s shoulder, a gesture of affection and resolve. “Now, get some rest. I have some plans to make. We’re going to find a cure for this, Harrison. We’re going to find it, no matter the cost.”

And as Lex walked away, the rain began to fall harder, and Harrison was left alone, watching the lights of Metropolis flicker, wondering how he could have a second chance at life, only to find himself at the center of a new kind of storm.