A white armored mutant viper slithered into the sewers with a bag in one of it's snake-head hands. Then the creature changed shape and shifted into the form of a beautiful teenage girl—Karai. She had just got back from scavenging for food. She had been able to catch some fish and some bags of tea. They were poor, but food was food. Ever since the Krangg invaided the city of New York and the Turtles had left, Karai and several human and mutant survivors had moved into the sewers, struggling to survive and stay away from the Krangg. Karai saw the Turtles escape in a party wagon with April O'Neil and Casey Jones. She saw how Leo was carried into the car, out cold and badly injured. He looked to be dead, but Karai hoped that he would live and recover.
It was him who helped her see the truth about her family. She remembered how they first met and she tried to befriend him then saved his life. She then turned on him because she thought at the time that Shredder was her father and Splinter took her mother's life. When Leo tried to tell her the truth, she didn't believe him. But then she overheard them talking about her being Splinter's daughter. She didn't know who to believe until she saw the pictures of her and her mother with Hamato Yoshi. She turned on Shredder and got locked up, stupidly believing that Karai would return to him. When Leo and the others rescued her and Splinter told her the truth about her mother, she ran out to get revenge on Shredder. It went badly when Shredder tried to mutate the Turtles and mutated her into what she was now. The stupid idiot.
When Splinter was defeated and left to die, Karai rescued him and nursed him back to health, along with a mutant alligator called Leatherhead. Now that she lost her brothers and almost lost her father, Karai was more than ever to make sure the Foot Clan and Krangg would pay for their crimes. While looking after Splinter and Leatherhead, Karai spied on her enemies and pulled many dangerous pranks on them. No one knew it was her causing all the trouble. Not even Shredder or the Krangg Prime. Just yesterday, she flattened the tire of one of the Krangg's trucks, causing a wreak that sent the driver and passengers to the emergency room.
Karai said nothing as she carried her quarry to their sanctuary where she rescued Splinter. Splinter was meditating when Karai arrived.
"Father."
Splinter looked over. "Miwa, just set it aside. I'll get to it later."
Karai did as she was told. It took her a while to get used to her real name over the last three months.
"I had to fight my way through a patrol of Krangg to get this stuff. They told me they wanted me to come with them so they could cure me."
"Do you want to be cured?"
At first, Karai was scared of her mutation. She lost control of her mind and attacked everyone in sight until Splinter brought her to her senses. She then spat venom in Raph's eyes and left in shame. Then she discovered that she could switch between her human and mutant forms at will. She didn't know why, but she realized at the time she returned to her human form, she was free. Free from the Shredder. Free to do whatever she wanted. She didn't need a cure. She was finally home.
"No." She answered, "I like my new form. Since Shredder was kind enough to mutate me, I should be thankful and use it all I can."
"I was worried sick when you became that. I thought I lost you again."
Just then, Leatherhead arrived at the campsite.
"Breaking news." he barked, "The Foot Clan lair is busy with a new shipment of mutagen. It's the perfect time for us to break in and spy on them."
Mischief sparkled in Karai's serpent-like eyes. "Actually, I just turned down an invitation from the Krangg to visit there. I think I'll pop in for a while."
"And get caught all over again?" said Splinter, "I won't allow anymore harm come to you by the Shredder."
"I didn't say he was going to see me."
Later, Karai, Splinter, and Leatherhead had broken into Shredder's lair. Outside the throne room, it was heavily packed with Foot Clan members, Kranggziods, and Footbots. They were all walking around either carrying something or patrolling. It was noisier than usual. Shredder was sitting on his throne with Rahzar, Tiger Claw, and Fishface before him. They were clearly in the middle of a meeting. Next to Shredder's throne was Hachiko, Karai's old pet dog. Though Shredder had claimed the Akita for himself, Hachiko was loyal to her. He was her dog. Hachiko got up and walked over to the air vents. No one saw him as he climbed in and crawled up to Karai, Splinter, and Leatherhead's hiding place. Splinter and Leatherhead jumped startled as the dog growled, afraid that Hachiko would start barking and blow their cover. But then he sniffed Karai as she shifted into a human. Hachiko recognized his mistress and trotted happily over to her.
"Hachiko!" Karai cooed quietly, "How are you, old boy? Did you miss me?"
Splinter and Leatherhead were surprised as Karai petted Hachiko. The dog wagged his tail and gave her kisses on her face.
"This is Leatherhead and my real father, boy." Karai whispered, "Be nice to them."
Ever since her mutation, Karai had the ability to talk to animals, and though they didn't talk back, they always understood her. Hachiko was no different. The dog went up to sniff Splinter and let both him and Leatherhead pet him. Karai gustured Hachiko to come over to her.
"Listen, boy. It's along story, but Shredder has lied to us my whole life. He is the bad guy now. We're going to have lots of fun with him."
Karai whispered to Hachiko. The Akita listened.
"Go, Hachiko, go on." She whispered.
Hachiko left the air duct and went back into the throne room. He ran over to the clock and, pressing a button with his paw, slightly sped it up. The traffic in the room when slightly faster. Shredder didn't even noticed as he continued his meeting. Next to Hachiko, a Kranggzoid set down a box of robotic parts to talk with another Krangg. Hachiko stole the parts and hid them inside the air vent before running off. When the Krangg picked up the box, it noticed that the parts were gone.
"Krangg," It told another Krangg, "The parts in this box are no longer in the box were they were. In what place are those parts that were in this box?"
"Krangg does not know, Krangg." Said the second Krangg.
Karai shifted into her mutant form and slivered down the edge of the vents without making a sound. Splinter watch anxiously as she shifted into her human form and slipped on a Foot Soldier mask before entering into the crowded throne room. She walked over behind a Footbot who was trafficking the Krangg and Footbots coming in and out. Whatever direction the Footbot pointed to, Karai pointed in the other direction. When the robot paused to figure out what was going on, Karai slipped her arms under the Footbot's arms. She signaled one party of Krangg to stop and a heavy cart to go, one of those new special indoor carts they used to get around faster. The cart ran over the Krangg and crashed into the wall, cracking a hole in it. Karai shifted into a snake and slipped back into hiding before the Footbot or anyone else could see her. Out of all the idiots Karai knew, Stockman-Fly happened to be driving the cart. Shredder and his mutant henchmen heard the crash and looked up.
"Stockman," Shredder said grimly, "Watch where you're going."
"It wasn't my fault!" Stockman-Fly protested, "That Footbot told me to go!"
Shredder didn't pay any attention as he turned back to the others. Hachiko ran up to the clock again and slightly sped it up. Everyone moved slightly faster, but it was a little more reckless than before. Now the Krangg and Footbots were bumping into each other and trying to avoid collisions. Karai got back to Splinter and Leatherhead in the vents. Leatherhead was amused by the cart crash, but Splinter looked sharply at Karai.
"Miwa, what were you thinking?" He scolded quietly, "You could have been caught. I don't want to lose you again."
Karai smiled, "If only you knew how long I've been getting away with this, Father. And they don't even know it's me. They're blaming Stockman."
Leatherhead raised an eyebrow. Karai peeked through the vent at the robots walking in the throne room.
"I think it's time to trip them up." She said.
"What are you going to do?" whispered Leatherhead, "There's too many for an attack."
"We don't need to go out there." Karai whispered slyly, "All we need is this."
She opened her hand to show a large black marble. She creeped over to the edge of the air duct.
"Watch and learn, Leatherhead. It's a weapon of mass destruction."
She dropped the marble down the air chute, which rolled down and out into the room. Hachiko watched as the marble rolled across the floor into the path of an unsuspecting Kranggzoid carrying a few mutagen canisters. It slipped on the marble and crashed to the floor with a clang, sending the canisters flying. Luckily, the canisters didn't break open and rolled across the floor. Karai stifled giggling in the vent. Another Krangg slipped on one of the canisters and fell into a box of robot parts. Shredder and his mutant henchmen heard the commotion and looked to see what happened.
"Be careful with those canisters, you clumsy fools!" growled Tiger Claw.
The marble kept rolling unsuspectingly across the floor. It flew up into the air as a Footbot tripped on it.
"What's going-?" Rahzar was cut off when he clutched his throat and stopped breathing. The marble had flown into his mouth and now he was choking. He urgently tapped Shredder on the shoulder.
"What now, Rahzar?"
Rahzar pounded himself in the chest, trying to dislodge the marble. Karai and Leatherhead were trying too hard not to laugh in the vents.
"It looks like he's choking, Master Shredder." Said Fishface.
Shredder rolled his eyes, moved up behind Rahzar, and started to use the Heimlich on him. In just four thrusts, Rahzar coughed and spat the marble out which rolled back into the crowd.
Rahzar gasped for air, "Thank you, Master."
Karai hoped that Rahzar would have choked to death, but that quickly went out of her mind as more Krangg and Footbots started tripping on the marble again. Karai made a hand signal to Hachiko. Once again, the dog ran up to the clock and sped it up. Now the Krangg and Footbots were running, trying to keep up with the clock. They were not just tripping anymore. They were running into each other. Boxes of robot parts and mutagen canisters were flying everywhere as the throne room broke into chaos. Karai watched, satisfied. She felt like she had done the world a huge favor. Splinter was both shocked and amazed by how much damage Karai was causing. Leatherhead, on the other hand, was quite enjoying it. Shredder, Rahzar, Tiger Claw, and Fishface stared around the room. They knew something was wrong.
"Slow down, you fools!" Shredder yelled over the crowd.
No one paid attention as the Krangg and Footbots kept running. Stockman-Fly was flying around catching the mutagen canisters, trying desperately not to let any of them break. In the confusion, several Footbots knocked Tiger Claw, Rahzar, and Fishface down the throne stairs. Hachiko ran up behind Shredder and bit him on the butt.
"AHH! Hachiko, you idiot!"
As Tiger Claw stood up, a Krangg carrying a box of paint cans ran into him. Some of the cans opened and spilled black paint on Tiger Claw, Rahzar, and several Krangg. Now the robots were slipping in wet paint, tripping on the marble and canisters, and crashing into each other. Hachiko let go of Shredder as the Foot Clan leader tried to get the crowd under control. Hachiko ran back to the air vent and up to Karai, Splinter, and Leatherhead's hiding spot. Stockman-Fly then saw the clock smoking and noticed that it was going too fast. He flew over to set it back, but then it blew up in his face in a cloud of sparks, fire, and smoke. The robots stopped running and returned to normal speed. A cart was unable to stop, and Splinter and Leatherhead winced as it plowed Shredder into the wall with a crunch.
Karai sneered, "Ouch. That's gotta hurt."
The marble rolled across the floor to the vent. Karai reached out and picked it up, putting it away in her bag. She looked over at Splinter and Leatherhead.
"Like I said. A weapon of mass destruction." She shifted to her mutant form and petted Hachiko. "Let's go home."
The four left the lair, leaving the Krangg and Foot Clan to deal with the mess. There were robot parts and canisters everywhere, Tiger Claw and Rahzar where covered in paint, Fishface's robotic legs were broken, and Stockman-Fly's face was covered in soot. Several Footbots helped removed a dazed Shredder from his crush against the wall. Karai knew that revenge felt good.