Reborn as a Saiyan in marvel

High above the city streets, William hovered with his arms crossed, his piercing gaze scanning the scene below. Mark, still catching his breath, handed Machine Head's unconscious body over to a squad of black-clad soldiers. Without a word, they activated their teleportation devices, vanishing in synchronized flashes of violet light. The villain was gone, whisked away to one of Cecil's undisclosed facilities.

Down below, the city was alive with celebration. A wave of applause rippled through the streets as civilians cheered for the young hero who had helped bring down one of the city's most notorious crime lords. Mark, clad in his signature yellow-and-blue suit, barely had time to process the overwhelming response before the crowd surged forward. Hands patted his shoulders, voices rang with gratitude, and people reached out to touch the hero who had saved their city.

"You're amazing, Invincible!" someone shouted.

"Thank you! Thank you so much!" another cried.

Mark smiled, his face alight with exhilaration. He had fought hard for this victory, and now, for the first time, he was experiencing the full weight of what it meant to be a hero. He shook hands, exchanged a few awkward hugs, and basked in the warmth of their admiration. But the moment was fleeting.

With a deep breath, Mark gently freed himself from the crowd and shot into the sky, rising toward William, who remained as still as a statue, his expression unreadable. As Mark reached him, he could barely contain the fire burning inside him, the rush of accomplishment, the thrill of making a real difference.

William finally turned his gaze toward him, his crimson and gold aura flickering faintly in the dying light of the sun. His tone was calm yet firm.

"You did well, kid. But you need to learn control." His voice carried weight, an authority that made Mark's excitement falter. "If you don't, every opponent you face will end up as nothing more than a fine pink mist."

Mark's smile wavered, his mind flashing back to the battle. He saw Tether Tyrant's grief-stricken face, the horror in his eyes after he had, accidentally, killed Magnamaniac.

For a moment, silence stretched between them. Then, with quiet resolve, Mark met William's gaze.

"Will you teach me?"

William didn't answer immediately. Instead, his eyes flicked toward the horizon, where the sun cast long shadows across the city. His irises gleamed momentarily, shifting through a spectrum of colors before settling back into their usual intensity.

The answer, unspoken but certain, lingered in the air.

William turned his head toward Mark and gave a single, firm nod before ascending skyward. The air thinned as he rocketed past the highest clouds, his crimson and gold aura flickering against the vast backdrop of space. Mark followed close behind, his body cutting through the atmosphere like a bullet. The further they climbed, the more Earth's blue curvature shrank beneath them, replaced by the endless black void of space.

Before long, they reached the moon. Its cratered surface stretched endlessly beneath them, illuminated by the harsh white glow of the sun reflecting off its surface. William hovered above the lifeless terrain, arms crossed, waiting. His presence was imposing even in the weightless silence of space.

Mark exhaled, steadying himself as he floated before his mentor.

Unbeknownst to either of them, a distant observer lurked in the shadows. A lone, cyclopean alien peered through a sleek, high-tech telescope, its singular, unblinking eye narrowing as it studied the pair.

"One of them must be the Viltrumite sent to conquer this world… but something's off. No mustache? That's unusual, but not unheard of. And the other one... who the hell is he?"

The alien's gaze lingered on William's distinct silhouette, his sharp, windswept hair, the casual yet commanding way he stood in the vacuum of space. There was an unsettling energy to him, yet nothing in the alien's vast knowledge provided an answer.

Still, it continued to observe, instincts warning that something significant was about to unfold.

Back on the moon, an invisible tension thickened the air as emerald energy erupted around William's body, crackling like a living force. The power rolling off him disturbed the moon's surface, sending plumes of dust spiraling outward in weightless waves. The ground beneath him trembled, tiny fragments of rock lifting into the void as his energy seeped into the landscape.

His voice cut through the silence, calm yet absolute.

"I've activated five percent of my power." His arms shifted to his sides, body radiating controlled devastation. "Now, I want you to hit me with everything you've got. No holding back. This is how you'll understand the difference."

Mark's expression flickered through a storm of emotions, confusion, hesitation, a touch of frustration, before finally settling into something resolute. He swallowed, nodding in understanding.

He clenched his fists. If William wanted to see his full power, he'd give it to him.

"CRACK!"

The surface of the moon beneath Mark's feet fractured in an instant, spiderweb cracks sprawling outward like a shattered mirror. A crushing silence filled the airless void, a deceptive calm before the inevitable explosion of force.

Then—

"BOOM!"

With the full, unrestrained fury of his Viltrumite strength, Mark launched himself backward in the opposite direction of William, his body vanishing into the endless abyss of space. The force of his takeoff sent a shockwave rippling through the moon's surface, displacing clouds of lunar dust that floated aimlessly in the low gravity.

William remained unmoving, arms still crossed, watching as his student was swallowed by the darkness on the far side of the moon. The distant stars twinkled like watchful eyes in the void, but he remained patient, his sharp gaze fixed on the expanse ahead.

Then, a flicker.

Far in the distance, a speck of light appeared, growing brighter by the second. The cosmos trembled in the wake of Mark's return, a swirling trail of cosmic dust forming behind him as he barreled forward with speeds that would make his father proud.

William's lips curled slightly. Good. He's pushing himself.

Mark was moving faster than he ever had before, his body cutting through space like a golden comet, his momentum bending the very fabric of the void. He clenched his fists, his muscles tightening like coiled springs as he honed in on his target.

Then, in a blink, he was upon him.

"BOOM!"

Mark's fist slammed into William's chest with all the power he could muster. The impact detonated like a nuclear explosion, sending an immense shockwave across the moon's surface. The ground beneath them cratered, and a pulse of kinetic force burst outward, displacing thousands of pounds of rock and dust into the vast emptiness of space.

But the moment of triumph was short-lived.

"KKKCHHHH!"

A sickening, wet crack echoed through Mark's body. His entire right arm, his fist, forearm, bicep, and shoulder, detonated into a violent spray of blood and bone, reduced to little more than red mist under the sheer resistance of William's unyielding body.

Mark's teeth clenched so hard they nearly cracked under the pressure. Every nerve in his arm screamed in agony, but he swallowed his pain, refusing to cry out. His breathing was ragged, his chest heaving as his entire body trembled from the shock.

His mind screamed at him to let loose, to roar, to scream, to do anything to relieve the unbearable agony coursing through his nerves.

But he knew better.

William would not let him take the easy way out. If he gave in and screamed, his mentor would shove a senzu bean down his throat rather than let him take it at his own pace.

So, he endured.

His knees slammed into the moon's surface, his one remaining arm pressing against the ground as he tried to steady himself. Sweat, mixed with traces of blood, dripped down his brow, freezing instantly in the vacuum of space.

Then, a shadow flickered in front of him.

William stood there, arms now at his sides, his crimson gaze unreadable as he observed Mark's condition.

There was no concern, no sympathy, just quiet evaluation.

Mark looked up, his vision slightly hazy from the pain, but his gaze locked onto the large, deep-red fist-shaped mark imprinted on William's chest.

He actually felt that.

William followed Mark's gaze and glanced down at his own chest. A thin, satisfied smile tugged at the corner of his lips. He reached up and brushed his fingers over the mark, feeling the residual heat from the blow.

He's definitely improving, William thought. To think he actually managed to cause damage at this level...

A slow nod of approval followed.

"Not bad," William said at last, his voice even. "You're getting better."

Mark let out a short, strained chuckle, despite the searing pain that flared through his body. Better? I just blew my damn arm off…

But despite himself, despite the pain, the exhaustion, and the raw frustration gnawing at the edges of his mind, he felt something else, something far greater.

Pride.

Because for the first time, in a long time, he had made progress. And if he could push himself to this level, then maybe, just maybe, he really could stand at the top one day.

He just had to survive the training first.

Allen the Alien was stunned.

He had traveled across galaxies, encountered some of the strongest warriors the universe had to offer, and even fought Viltrumites firsthand, but this was something else entirely.

The force behind that blow… It wasn't just powerful; it was terrifyingly strong.

"That strike had to be at least on par with a mid-level Viltrumite… maybe even higher," he thought, his single eye widening as he lowered his advanced telescope. The dust cloud left in the wake of the impact still lingered, dispersing into the void like remnants of a dying star.

A mix of awe and apprehension settled in his gut. I need to keep watching… I need to know more. But one thing is certain, I have to report this to the Coalition.

Then, an odd thought struck him.

"Could I withstand a full-powered blow from that guy?"

His brow furrowed. A question for later.

For now, his curiosity overpowered his caution. He lifted the scope again, his gaze honing in on the two fighters below.

William stood before Mark, casually handing him something small, Allen couldn't make it out clearly from this distance, but the moment Mark swallowed it, his severed arm began regenerating almost instantly. Within seconds, muscle, tendons, and bone knit themselves back together like it had never been destroyed in the first place.

Allen's eye twitched. What the hell kind of training is this?!

Before he could process his amazement, the battle resumed.

"BOOM!"

Mark exploded forward, his entire body moving with purpose. His new arm functioned as if it had always been there, no hesitation, no adjustment, just raw, determined movement.

He twisted his body mid-flight, momentum carrying him into a brutal axe kick aimed straight for William's skull.

"WHAM!"

William raised his forearm just in time, absorbing the impact effortlessly. The sheer force of the kick sent ripples of energy surging outward, fracturing the already fragile moon rock beneath his feet.

Undeterred, Mark didn't let up.

Using the momentum from his blocked strike, he flipped backward with masterful agility, his body arcing through the low gravity before he immediately rocketed forward once more. His fists clenched, his jaw tight with resolve, this time, he wouldn't hold back.

"BOOM! BOOM! POW! BANG! BOOM! BOOM! POW!"

A relentless barrage of punches and strikes rained down, each blow packed with explosive force.

Mark moved with the ferocity of a storm, his attacks fluid, precise, and brimming with controlled rage. His muscles burned, his blood roared in his ears, this was what he needed. He had to push himself past his limits.

And yet—

William barely moved.

His form remained almost entirely still, arms shifting only when necessary, effortlessly blocking and parrying nearly every attack. His focus was unwavering, eyes locked onto Mark with the gaze of a seasoned predator.

Mark gritted his teeth as his fists clashed against William's forearms, each impact sending shockwaves through his own bones.

But despite William's near-impenetrable defense, two of Mark's punches managed to slip through, one grazing his ribs, the other just barely clipping his jaw.

It wasn't much.

But it was something.

And to Mark, it was proof that he was getting somewhere.

For Allen, however, it was confirmation of something far more significant.

His grip tightened on his telescope, pulse quickening as realization settled in.

"That guy... whoever he is... he's not just strong. He's on an entirely different level."

And that terrified him.