Disclaimer: I dont own anything except for the oc in this story.
Note: This story is an alternate universe of the 2012 cartoon. Here Karai wasn't mutated and chose to stay in the foot cause she knows Shredder would of wanted even more vengeance if she chose to stay with the turtles. So Karai is working against Shredder behind his back and Shredder has no idea that she knows the truth. And it is different from the show from there onward.
It was a plan, a tactic, that only a truly evil heart as Shredder's could come up with. Not only would he be insulting Splinter's decision years ago to his face. But it will also knock the turtles high and mighty leader down a peg. Shredder will use Leonardo's own flesh and blood against him. Even if it takes some time. Shredder has waited 16 years for revenge on Yoshi, what's 15 or so more?
And so he had one of his female foot soldiers ambush Leonardo when he was alone. She threw blinding powder at Leo and knocked him out. And Leo had no idea what happened or how much his body was used by that foot kunoichi. Months later and Shredder had his newborn pawn.
The baby turtle was male. Healthy bright green skin and a strong dark green shell. He had beautiful dark eyes and was just perfect.
Karai had to use all of her willpower to keep her emotions in check. But when she saw him, she couldn't stop herself from falling in love. And her heart clenched in pain as she realized that this precious baby boy of Leo's was going to be turned into a heartless killer. She just couldn't let that happen!
"Father. I would like to make a request. I want to take care of and raise this child myself. I'll teach him. He would be conditioned to see me as a mother, so he would think of you as a grandfather. So he would need to obey you even more." Karai said. But truth be told, she wanted to protect Leo's son. She can't let Shredder brainwash him and manipulate him like he did to her.
Shredder agreed. And Karai named the baby turtle Shikame, combining "shishi- lion" and "kame- turtle". She loved and raised him as if he was her own. Shikame was so much like Leo. He was naturally skilled with ninjutsu. He learned to fight with a tanto and a sword. He was happy and innocent and oblivious to the evil living with him.
Karai did her best to keep him that way. Behind Shredder's back she took Shikame out at night on a walk through the city. He loved their walks together. She showed him things like love, mercy, family, and others that she wasn't shown. She taught him right from wrong. And most importantly, how to put on a convincing act and how to keep a secret.
He thought it was a game. Act like a perfect emotionless disciplined ninja for Shredder. He began calling it "ninja mode". Over the years it became easy to slip into ninja mode. And when he was a toddler he began asking questions about his father.
"Mama, who's my father?" The young turtle tot asked his mother as she looked over he practice for today. Karai stiffened but managed to stay calm.
"His name is Leonardo, a turtle just like you." She said, keeping short sweet and to the point.
"What's he like? Is he a ninja too?" Shikame asked again. Karai let out a quiet sigh. She knew these questions would come one day.
"Yes. He's an amazing ninja. A wonderful leader. And someday will overcome Shredder himself." She said. The 5 year old turtle tot gave a nod with a cute determined look.
"Ok. I'll work really hard to be a great ninja too." He said as much bravado as the tot could muster. Then he continued his practice with a newfound determination.
Karai watched him with both joy and pain. Someday there will be a chance to get him away from this place. He'll find the turtles and then they will both be free.
It was the day of his 15th birthday, and Shikame was going to ask Karai a very important question. He was in his room, standing in front of a mirror. He tightened his black mask around his face, made sure his spiky shoulder pad and belt was straight, and checked his metal elbow and knee pads were shiny. Then he stood up straight in a dramatic pose and grinned. He was ready for the day.
After his training with Master Shredder and practice, he Karai's attention when he was done. "Mother. I would like to ask you a question." He said. Karai nodded at him to continue.
"Well... I am 15 now and I was thinking, I want to find my father. I've worked so hard and I think I'm ready now. I know you've said I was too young before, but I've grown. I'm much more mature now. And... I think he would be proud of me." Shikame said, trying to remain confident but faltering at times.
Karai let herself smile a bit. "You're ready. You must leave tonight. I'll help you with that. And I'll tell you where you can find them. But you must find them on your own. And, most importantly, you must not return once you leave. Don't ask why." Karai said. Shikame gave a quick nod.
"Ok Mother. I don't quite understand. But thank you." Shikame said, showing some of his excitement. Karai smiled again and gently placed her hand on the side of Shikame's face. "My little shishi." She said.
That night, Karai lead Shikame out of Shredder's lair. They dodged the night guards and she dropped him off in an alley. She told him that they lived underground. But he would have to find them on his own. And finally he was off, using his skills and knowledge to find them.