The beginning of this is pretty much the same as in the show, up to the point where the fight starts, then it's all me. Aiming for a more serious and suspenseful remake of Yumi vs Evil Yumi.
"You're armed, aren't you?"
Yumi implored her point to Ulrich, and he looked down at his sword. She felt his sword slash her body as her virtual form dissipated and returned her to the real world. Yumi felt quite astonished at the day's events. She had been trapped for who knows how long on Lyoko, and now she heard X.A.N.A had made an exact duplicate of herself? When she had first joined her friends against the evil A.I., she knew things would get crazier as time went on. The gigantic teddy bear was the peak of it for her, but now he had crossed the line. She felt adrenaline stir within her, as she would need it for what came next.
"Too easy" The clone of Yumi thought to herself. She had effortlessly knocked out Jeremy with just a single punch. This a rather unique gamble by the A.I, having tried indirect methods of killing his enemies for so long, a more direct approach was required. The clone had aroused suspicion with her aggressive tactics, but so far her mission was nearly at it's end. Granted it had been made virtually, but still she was flesh and blood. No different than Aelita before she had set into Lyoko that fateful day, except the circumstances of her birth. Now all she had to do was unplug these scanners, throw Jeremie to his death, and watch her master's triumph unfold from there.
That is, until the last scanner had opened up. Turning towards it, she would see the girl had been founded upon in her creation. "You know what? You look just like me when i'm having a bad day". Yumi had trained in martial arts, and she had little doubt that her evil twin would have some similar capability. Though she had been slightly annoyed by the interference, the clone was actually rather pleased. Jeremie was absolutely no challenge, but Yumi? This would prove interesting.
She glanced at Jeremie. Better to finish him off after she took care of Yumi, she thought. Setting into a fighting stance of her own, the evil twin smirked. "You really think you can beat me, human?"
"Absolutely" Yumi sneered. Normally, Yumi was the most reserved of the group. But something about the prospect of someone attempting to kill her friends made her less restrained. Yumi had always wanted a chance to punch the evil A.I. in the face, but now came the second-best option. They stared at each other for a bit, then the clone struck forward with a high kick. Yumi ducked under it, delivering a hard punch to her evil twin's stomach.
The clone staggered back, but that was far from the end of her. As Yumi threw a karate chop, the clone would block with her arm and send a punch into Yumi's face. It connected quite effectively, Yumi holding her nose in pain. She had been in fights before, and she had even met Ulrich during martial arts practice to begin with. But this? This was no competitive sparring match. Her opponent was out to kill, and unlike literally any other human the Lyoko Warrior had met, the clone's sole purpose was just that.
In that case, why should she hold back?
The clone charged forward for another kick, but Yumi ducked and lashed her leg out, tripping her clone. Mounting her twin, Yumi pinned her down and started pummeling her. Her head slammed into the metal floor several times, while Yumi continued her brutal assault. Both knew it was a battle to the death, and both treated it as such.
Jeremie has had an awful day. From the everyday stress of dealing with X.A.N.A, from being accosted by his friend's unusual behavior, and then noticing a problem with the scanners. When he went down there, his problems would be even worse. "Yumi's" punch had shattered his glasses and left the poor teenager on the floor unconscious. Slowly, his eyes began to open and he groaned. "What...what happened?"
"Jeremie! Get out of-"
Yumi's desperate attempt to get her friend away from the scene resulted in a punch to her face from the evil twin, who got herself up from the ground. Jeremie rubbed his eyes to see if he was hallucinating; he definitely did not recall two Yumis in his life. Then he would notice something pulse on her head. A while symbol that resembled an eye, a symbol that the computer genius was all too familiar with. Then Yumi grappled with her clone again.
"Get back to the computer and help Aelita deactivate the tower! I'll handle this!"
Jeremie had by now grasped the situation. His fighting skills were absolutely abysmal compared to the rest of the gang, and what happened a few minutes ago was a stark reminder of that. Seeing no other option, he pressed the button in the elevator, went in, and closed the door. His vision was still quite dizzy and disoriented, and he would be of very little help in this state anyways.
"Good luck, Yumi!" Her friend offered words of encouragement as he departed, and the two women were left with no distractions once again. By now, Yumi and her clone had no words to say to each other. As the clone threw a kick, Yumi stepped forward to block it and hit her evil twin with a backhand before launching a three-punch combination. She deftly blocked Yumi's follow-up strikes and countered with a jab of her own, landing on Yumi's left cheek. She followed up with a vicious kick to the chest that knocked her enemy over.
Yumi glared at her clone as she got up and slammed her knee in her evil's twin's stomach, before she gripped the back of her head and shoved it down while bringing her knee up and hitting the clone dead on in the nose. When the head rocked back, Yumi stepped forward and rammed her elbow into her clone's damaged nose.
It was from that point Yumi could see that her clone was high on pain-tolerance, although she could clearly feel pain. Yumi had definitely broken her opponent's nose with that last hit, but she was nowhere near finished. The Lyoko Warrior would learn that the hard way when her clone countered with a high kick that struck Yumi's face.
The clone continued her assault with a series of swift punches. Yumi blocked as many as she could, but could not stop all of them from hitting her. The clone continued her relentless assault, until she obtained a solid punch against Yumi's ribs. Grunting in pain, Yumi gave ground and began to fight defensively. In desperation, she did a move not normally endorsed in martial arts: the headbutt. The clone appeared very much caught off-guard as their heads collided. Yumi did not waste the opportunity. She spun around and executed a roundhouse kick, catching her clone across the jaw.
Her evil twin would hit the floor with a shout of pain. Rolling to her feet, the clone initiated the next attack with another series of punches and shove her opponent against a scanner. Yumi could not do this forever. Whatever training she had, she was still only human. Humans had limits to their energy, and her clone seemed to just get angrier with every hit she landed on her. She thought to herself that her friends must be close to the tower by now.
Grappling and trading punches with her opponent, Yumi was backed against the scanner, and the clone tried a new tactic. "If you're going to kill someone, little girl..." The clone would attempt to prove her point by wrapping her hands around Yumi's throat, intending to strangle the life out of her opponent. "You get in close. Personal. That way they know you're serious."
The clone's face was just inches away from Yumi's own, as if she wanted to watch the light in her eyes go out. She would be getting her wish. Yumi could feel the breath leaving her as the clone squeezed tightly. Then she relied on instinct, and she drew her hand and flicked her finger into her clone's right eye. Her evil twin would let go of her throat with a shout of pain.
"Then you should know i'm very serious"
Yumi would take the opportunity to show her determination by sweeping the evil twin's legs from under her. Then before she could get up, Yumi lifted her leg up and landed a stomp directly on the twin's face. A loud crack could be heard, no doubt her clone's already broken nose caused her even more pain. Normally, this would incapacitate most opponents Yumi had faced, but the clone's response was to pull on Yumi's leg and send her to the ground with her.
The clone attacked with much more ferocity as she landed punch after punch on Yumi's chest and face. There was less coordination but more speed, as if she had become feral. The women began screaming at each other, loudly, as they landed blow after blow, as if both were beyond annoyed the other hadn't fallen yet. Combat was vicious, bruises and scratches piled up fast, but Yumi was suffering more. She could not keep this up. Attempting to crawl away, Yumi found herself grabbed by the leg.
"Go to hell!" Yumi found herself snapping. Couldn't she get a moment's peace from this evil twin? She rolled over and brought up her other foot, slamming it into her clone's face twice before her evil twin's other hand found her kicking leg.
"I'll go to hell when you're dead, you stupid girl!" the clone snarled as she climbed on top of Yumi and headbutted her.
Yumi could not get up now, dazed and in pain. She moaned as she felt her battered and bruised clone climb on top of her, straddling her arms and pinning her wrists. She sneered down at her and landed her fist onto her face, clear the clone planned to savor this moment and kill her slowly. A second punch hit her hard in the eye and it rocked her head from side to side and back and forth.
"When I'm done with you, i think I'm going go even slower on your friend." The clone could not not help herself but taunt her opponent as she gained the upper hand.
Anger flared and Yumi opened her mouth. She caught her evil twin's fist between her teeth and bit deeply, drawing blood. She had already been quite angered before the fight had begun, and the threat to Jeremie reignited it. Now the clone was throwing punch after punch in Yumi's face to get her to let go, with her other hand. Then she did so, her energy utterly spent in that last act of defiance.
The injury to one of her hands did not deter the clone's plan to simply beat her opponent to death. Yumi could barely even move by this point, so much so that the clone saw fit to stand up and kick Yumi in the face, cracking a couple of her teeth. Yumi spat them out along with a mouthful of blood. Then the clone brought her leg down and stomped. A loud crack was heard, and now Yumi had a broken nose as she began to drift out of consciousness. Yumi could not take much more.
As if seeing this, the clone let out an evil grin. As the evil twin raised her leg to stomp on her again, something happened. Yumi could see the clone clutching it's chest and gasping. Was it suffering some kind of internal attack? The clone's eyes bulged and it became speechless as Yumi realized what had happened. From where she failed, her friends succeeded.
It appeared that a heart attack, or something similar to it, had enveloped the clone as it collapsed to the floor right beside Yumi, unmoving. X.A.N.A had undoubtingly planned to simply discard the clone by deactivating it's tower once it had served it's purpose, but Aelita had done so first. It's lifeless eyes were staring down, and Yumi looked right back at it.
She wasn't quite dying, but that brawl went very badly. Her face was a bloody and bruised mess. Yumi had no doubt her clone has caused so much trouble to the point where Jeremie would launch a return to the past as usual. Her prediction was fulfilled when she heard saw a bright light coming towards her and enveloping the scanner room. Effectively, today's events had never even happened.
As the light consumed her, she smiled. She had won.
Author's Note: Imo, I'm pretty sure the clone in Image Problem wasn't really a polymorphic specter. But a virtualized human made manifested after X.A.N.A created it. I always felt Yumi vs. Evil Yumi could've been an epic fight, if better chorography had been around back then. Also felt Yumi's hand-to-hand skills were sometimes underutilized in the show.