AUTHOR NOTE: I have no right to Marvel/MCU or any other characters mentioned in the story except for the OCs. This is just a fanfic so enjoy it.
Tom's eyes fluttered open, greeted by the dim light filtering through the broken blinds of a rundown apartment. The ceiling above him was cracked and discolored, water stains forming grotesque patterns. The air smelled of mildew and old sweat, and the mattress beneath him was thin, barely a cushion against the creaky wooden floor.
He sat up with a groan, his body aching in ways he didn't recognize. A dull throb pounded at his temples as he rubbed his face, only to freeze when he caught sight of his hands. They were rougher than he remembered—calloused, with faint scars running along his knuckles. His breath hitched. This wasn't his body. It was similar, but subtly different, as if shaped by experiences he didn't have.
Panic clawed at his chest as he stumbled to his feet, nearly tripping over a pile of clothes on the floor. He staggered toward a cracked mirror hanging on the wall. The reflection staring back at him wasn't entirely unfamiliar—it was him, yet not him. His dark brown hair was unkempt, his face slightly gaunter than it should be. His green eyes held a sharpness that hadn't been there before.
"What the hell…?" he muttered, his voice hoarse.
Then, it hit him.
A flood of memories crashed into his mind like a tidal wave.
He gasped, gripping the edge of a rickety table to steady himself. The memories weren't his—or rather, they were his, but from a different life. A life where he had run away from home, chased by authorities and secret organizations after his mutant abilities had been discovered. A life where he had lived on the streets, surviving with nothing but his wits and the uncanny ability to turn into any kind of cat—whether it be a common alley cat or a majestic panther.
He remembered cold nights in abandoned buildings, the hunger gnawing at his stomach, the constant fear of being caught. He had fought, stolen, and evaded those who sought to control him. It had been a harsh, lonely existence.
But then… how had he ended up here?
Tom pressed his fingers against his temple, trying to make sense of it. This wasn't just a dream—he knew these memories were real. He had lived them. But he also knew his other life, the one where he had been a normal high schooler who loved anime and movies.
Had he been…isekaid?
Before he could spiral further into confusion, a sharp mechanical beep rang in his ears.
[Ding!]
Tom spun around, his heart hammering. The sound hadn't come from anywhere physical—it had echoed inside his head.
[Congratulations, Host. You have received a one-time Upgrade System. Your mutant ability has been enhanced to Tier 5, reaching the pinnacle of Omega-class mutants. This system has now fulfilled its function and will be permanently de-activated.]
Tom's mouth fell open.
"What?" he blurted.
There was no response.
He waited, half-expecting more information, but the voice—or system, whatever it was—had gone silent.
"Hey! What do you mean, 'de-activated'? Hey what's happening!"
Nothing.
It was as if the system had never existed.
Tom clenched his fists. His mutant ability had been upgraded? What did that even mean?
He had already possessed the rare power to transform into any feline, adapting his senses and physical abilities based on the species he chose. But Tier 5? Omega-class? That was far beyond his imagination. Omega class includes powerhouses like Phoenix(Jean Grey), Magneto, Iceman and even the reality bending kid Franklin Richards.
A rush of energy coursed through him, burning under his skin like wildfire. His instincts sharpened, his body felt lighter—as if he could move with an agility he had never possessed before.
Without thinking, he focused on his ability.
The change was instantaneous.
One second, he was standing in the middle of the apartment—the next, he had shrunk down, his body morphing seamlessly into that of a sleek black panther. He hadn't even needed to concentrate as hard as he used to. It was effortless.
Tom's sharp feline eyes darted around the room. Every detail was clearer than before—the cracks in the walls, the dust particles floating in the air, the faint scurry of a rat behind the drywall. His ears twitched, picking up distant conversations from the street below.
He took a step forward, his paws silent against the wooden floor. His muscles coiled with power, strength thrumming beneath his fur. He felt unstoppable.
Then, with a thought, he shifted again. His body shrank and morphed until he stood as a tiny housecat, barely making a sound as he padded across the room.
This is insane.
The transformation had never been this smooth before. He could shift instantly, without delay, and each form felt even stronger than the last. If this was what it meant to be an Omega-class mutant… he had just become something far more dangerous than he had ever imagined.
He decided to try something different this time because if his thinking was right then he could turn into any feline, even mythical or imagined ones from movies (which also may be real in some other world).
What's the strongest cat he knew of?
He concentrated and tried to imagine changing into a Nimeon Lion, the invulnerable monster from Greek mythology, the next moment he shifted into a huge lion with golden fur. But it was a little crammed in the room due to its size.
Tom changed back into his human form, breathing heavily. His heart pounded in his chest, not from exertion, but from the sheer realization of what he had become.
He had no idea how or why he had been thrown into this new life. No idea what had caused this upgrade system to appear before vanishing without a trace.
But one thing was certain.
Whoever had been after him before—whoever had wanted to control or eliminate him—
They had no idea what they were dealing with now.
A slow grin crept onto his face.
For the first time in a long while, he wasn't just a scared runaway anymore.