Chapter 1: Broken Swords

As the moon rose high over the Manhattan skyline, Leonardo, Donatello, Raphael, and Michelangelo were getting ready to go with Splinter, their father, and rescue Karai from the Shredder.

Leonardo was sick with worry. He had tried to stop Karai from going to face him alone...

*flashback* Leonardo opened the divider to Karai's new room at the lair.

"Karai? You awake?" he started. When he received no response, he left and waited in the living room. He saw Karai run through seconds later and hopped down in front of her.

"Don't try to stop me, Leo," she said, staring him down.

"I'm coming with you."

"What?!" Karai was taken aback.

"Shredder isn't going to stop hunting us unless we take him out. I'm not taking 'no' for an answer, Karai," Leo replied, looking her directly in the eye.

Karai smiled and walked over to Leo, leaning over him slightly. He glanced around, blushing noticeably. She leaned in as if to kiss him, then suddenly punched him in the stomach and threw a smoke bomb to knock him out. That was the last thing he remembered before waking up and realizing she was gone. He yelled for his brothers and father.

"Karai left! She's gonna take on Shredder alone!" he exclaimed.

Splinter looked to the side. "I told her too much, too quickly. We must go, now!"

With that, they climbed aboard the Shellraiser and went to rescue Karai. *end flashback*

As the mutants were on their way, the Shredder had easily recaptured Karai and was having her taken to Stockman's laboratory. The turtles spotted them as they sped along the streets.

"Time to knock them off the road!" Raph exclaimed.

"No! There are too many of them; if we start a fight, we may not be able to handle all of those carts!" Splinter interjected before Raph could fire. Raph grunted, but nodded.

The Foot legion came to a stop at a seemingly abandoned warehouse; but inside was a laboratory run by Baxter the Fly. He was putting the final touches on his homemade mutagen.

"Is it ready, Stockman?" Shredder asked from behind the fly, shocking him and causing him to spill some ingredients into the mutagen.

"That'll be fine..." he muttered, then replied, "Yes, master Shredder!"

Shredder had Karai caged up and hung above the giant vat of mutagen, evoking a shocked look from Tiger Claw.

"Mutating your own daughter? You're more ruthless than I thought..." he murmured, in both fear and respect.

"She is not to be mutated. Stockman has added serpent DNA into the mutagen; when the turtles attempt to rescue Karai, they will be mutated into mindless natural predators of rats! And then, once Splinter's spirit is broken, I will shatter his body!" Shredder exclaimed with a look of triumph in his eyes.

Suddenly, the Shellraiser crashed through the wall of the warehouse, and the turtles, along with Splinter, hopped out.

"Let. My. Daughter. Go," Splinter demanded with a deathly calmness.

"Come and get her... If you can," Shredder taunted.

Splinter leaped at Shredder and began attacking him as Shredder laughed gleefully.

Dozens of FootBots attacked the turtles, but they managed to hold them off. Just as the fight was turning in their favor, Donnie stepped into what he quickly realized was a trap. He attempted to warn his brothers, but he was too late- Mikey and Raph stepped into them as well, leaving only Leo.

Finally, even Leo stepped into a trap, but luckily, his sword was left sticking out. He used it to pry the cage open, then leaped over and cut a chain linked to the roof, riding it up to Karai's cage. He quickly opened it and undid her bonds. She grinned at him.

"Thank you, Leo!" she exclaimed. His face lit up, but the distraction proved a disaster.

"Leonardo, behind you!" Splinter exclaimed. Karai got the warning in time and leaped from her cage to the ground, but Leo was still dazed. He barely had time to lift his swords to defend himself from Shredder's attack, but the force of the impact broke them and knocked Leo down towards the mutagen.

Everything seemed to play in slow-motion as Leo fell. Splinter, Karai, and the other turtles were horrified as they were helpless to do anything. Shredder, having escaped falling in, started to cackle with pure joy. A chorus of, "LEO!"s ran out with a very distinct and heartbroken, "Leonardo!" ringing out from Splinter.

A very different Leonardo surfaced from the mutagen. His head was in the shape of a cobra's, with blue designs around his eyes. His shell had turned into armor, and his broken swords had turned into spikes on his arms. Finally, his legs had merged into a long tail with a stinger on the end. He slithered out and started attacking FootBots, letting out a mix between a roar and a hiss, as Karai and Splinter quickly freed the turtles from the traps.

Splinter turned to Shredder, who was clearly enjoying his pain.

"You have gone too far this time, Oroku Saki!" he cried as he charged at Shredder and knocked him down. Shredder was shocked, but he kicked Splinter off towards the wall. Before Splinter could charge again, sparks from a destroyed FootBot hit some spilled oil and set the whole lab ablaze. Rubble began falling from the ceiling, separating Splinter, Karai, and the turtles from Shredder, Tiger Claw, and what used to be Leonardo.

"Father, we have to go!" Karai exclaimed as more of the building collapsed around them. Splinter gave a defeated look and nodded.

Later, at the lair, the five were sulking around, almost not believing what had just happened. All of them wondered if it was just a bad dream. Karai curled up in a ball and tried to hide her face.

"Miwa..?" Splinter started, trying to comfort her. She looked up, tears screaming down her face.

"This is all my fault! I went off to fight Shredder alone... I didn't listen to you... I got Leo involved... It's because of me he's a monster!" she half-screamed. The turtles all went wide-eyed from this; they were all feeling similar things, but Karai wasn't one to act like this most of the time.

Everyone's eyes began to water as the all drew in for a family hug. They were safe now, but nobody had a clue what had happened to Leo, or how they were going to fix this.