The city pulsed with quiet tension as Karai and her Foot Soldiers moved through the dimly lit streets, their eyes scanning for any sign of movement.

Karai's voice was sharp as she addressed her soldiers. "The turtles have been spotted in this neighborhood. Stay alert."

She paused as a sudden burst of laser fire echoed through the alleyways. The familiar hum of Kraang weapons filled the air.

Karai held up a hand, signaling her Foot to stay back. She moved silently, slipping into the shadows as she observed the scene below.

The turtles were locked in battle against the Kraang, dodging and weaving through the barrage of attacks.

Mari fought alongside Raph, her tanto flashing as she moved in perfect sync with him, taking down a Kraang with a ruthless efficiency. Nearby, Cat ducked under a laser blast, spinning on her heel as she threw her tessen with pinpoint accuracy. It struck a Kraang droid's exposed wiring, sending it sputtering to the ground.

One of the Kraang droids spoke in its garbled, mechanical tone. "When fight is concluded, the ones called the Turtle are defeated by Kraang."

Karai raised an eyebrow. "They're fighting robots?"

As she watched, the metal exoskeleton of a Kraang suit hissed open, and the squirming pink alien inside slithered out. Her eyes widened slightly.

"Whoa," she murmured, intrigued. "This town's more interesting than I thought."

She remained still as Leo noticed her.

Suddenly, Leo called out, "I got you, Raph!"

Raph turned, irritated. "What? I don't—"

But before he could finish, Leo leaped in and deflected an attack meant for Raph—even though Raph had already dodged it.

Leo didn't stop there.

"Mari, behind you!" Leo shouted, rushing in before Mari could react.

She had been about to block an incoming Kraang's attack—but Leo intercepted, knocking it away like she couldn't have handled it herself.

Mari scowled. "Leo, what the hell?"

Leo turned sharply again. "Cat, get back! You're in danger!"

Cat, who had just effortlessly dodged and countered a Kraang's attack, turned, confused. "Wait, what? I literally just—"

Leo rushed forward anyway, blocking her from a non-existent threat and forcing her back toward the others.

Mikey blinked. "Uh, dude. What's with you?"

Leo ignored them. "Donnie, behind you!"

Donnie, who was clearly not in danger, frowned. "The wall?"

Before he could react, Leo was already there, slicing a Kraang in half before it could strike. As the alien collapsed, Leo's gaze flickered upward—to where Karai still stood in the shadows, watching.

For a brief moment, they locked eyes.

Then, with a smirk, Karai turned and disappeared into the night.

Mari, having caught the whole thing, narrowed his eyes.

Donnie wiped his brow, clearly confused. "Uh... what the heck was that?"

Mikey grinned. "Yeah, you trying to impress us? 'Cause it totally worked."

Mari folded her arms, eyes locked on Leo. "No, it didn't. He's acting weird."

Cat flipped her tessen shut, giving Leo a long look. "Leo, what's going on with you? Since when do you fight for us instead of with us?"

Raph took a step closer, suspicion flaring in his eyes. "Yeah. What's with the whole saving everyone thing?"

Leo tensed. "I was just—helping."

Mari scoffed. "Helping? You jumped in like we were helpless."

Leo avoided her gaze. "I don't know what you're talking about."

Donnie crossed his arms. "Raph, what is it?"

Raph's glare didn't waver. "I thought I saw something. What about you, Leo? Did you see something?"

Leo hesitated for just a second before shaking his head. "No."

Raph didn't believe him for a second.

"Turtles first, right?" Raph pressed.

Leo's expression didn't waver. "Turtles first."

Donnie exhaled, rubbing the back of his head. "You feel like we're missing something?"

Mikey shrugged. "All the time."

"Same," Cat says.

"This is new for me," Mari added, "and I don't like it."

Mikey leaned over April's shoulder, watching as she carefully dabbed the inside of her mouth with a cotton swab. His eyes widened.

"Whatcha doing, April?" he asked, tilting his head.

April didn't look up as she sealed the swab in a small test tube. "Sending in a sample for a class project."

Mikey's face lit up with excitement. "Wait—you're mailing in your spit for a class project?" He grinned. "Man, school sounds awesome!"

Across the room, Mari snorted. "Yeah, well, that's because you're an idiot."

April's expression was deadpan. "It isn't."

Mikey leaned back, undeterred. "Well, I'd be awesome at it. Check this spit out—"

He took a deep breath, ready to demonstrate.

Before he could, Donnie clamped a firm hand over his mouth. "Don't," he warned.

Mikey groaned, voice muffled. "Dude, rude."

Donnie ignored him, adjusting his glasses. "It's not about spit, Mikey. It's about DNA."

Mikey blinked. "D-N-what now?"

From the couch, Cat perked up. "Ooooh, I know this one!" She twirled a strand of hair around her finger. "DNA stands for... uh... Dramatic Ninja Abilities?"

Mari facepalmed. "You're so lucky you're cute."

Donnie sighed, already regretting engaging. "DNA. Genetic code. The building blocks of life. It's a microscopic blueprint that tells every living thing what to grow into and—" He cut himself off, pinching the bridge of his nose. "Why am I still talking to you?"

Mikey grinned. "I don't know. You'd think you'd have learned by now."

April smirked, setting her sample aside. "Everyone in my class is sending in a DNA sample to this research group—the Worldwide Genome Project. Then they'll send us a report about our ancestors. Neat, huh?"

Cat's eyes sparkled. "Oooh! Like a princess lineage test? What if I'm, like, royalty from some ancient civilization?!"

Mari rolled her eyes. "Yeah, sure, Cat. You're the long-lost Duchess of Dumbassery."

Cat pouted.

Mikey nodded, feigning interest. "Uh-huh. Uh-huh, uh-huh. Wow. It's amazing what they can do these days."

April raised an eyebrow.

Mikey's face split into a grin.

"Just kidding."

"So, are you gonna tell the others about her?" Raph's tone was casual, but there was a sharp edge to it.

Leo didn't look up from where he was adjusting his gear. "No need. We had a little chat, and, uh... she's gonna leave us alone."

Raph snorted. "Oh, right, because villains always back off when you ask them to. Maybe I'll text the Kraang and ask them to stop mutating stuff."

Leo clenched his jaw. "Drop it, Raph."

Across the room, Mari raised an eyebrow. "Wait—who's 'her'?"

Cat, stretched out on the couch, perked up. "Ooooh, is Leo hiding a secret ninja girlfriend?"

Leo stiffened. "No."

Cat smirked. "That was way too fast. Now I wanna know."

Mari crossed her arms. "Yeah, what's going on?"

Leo shot Raph a warning look. Raph just smirked, but for once, didn't spill anything.

Before Mari could push further, Mikey popped his head into the conversation, balancing a spatula in one hand. "Okay, guys, what do you want: omelet pizza or pizza omelet?"

Raph frowned. "What's the difference?"

Mikey blinked. "Okay, you caught my bluff."

Before Mari could express her disgust, a loud chime interrupted them—their T-phones buzzing in unison.

Donnie frowned, pulling his out. "Hey, did you guys just get a mass text from April?"

Everyone checked their screens.

Leo sighed. "Yep."

Raph squinted at the message. "Is she saying she's being attacked by an old lady?"

Mikey gasped. "Guys! This is it! The robot grandma uprising I've been warning you about!"

Mari gave him a deadpan look. "Mikey, no."

Cat, however, looked intrigued. "Wait, wait—what if that's actually happening? Imagine— an entire army of grandmas, walking really slow, knitting their evil plans."

Mikey's face lit up. "And they'd hit us with purses full of bricks!"

Mari groaned. "I hate that I'm related to you two."

Leo stood up, grabbing his swords. "Let's go!"

The high school loomed over them, an eerie emptiness stretching through the halls as the turtles crept inside.

Mari adjusted her grip on her tantos, scanning the darkened corridors. "I don't like this."

Cat hugged herself, glancing around with wide eyes. "Feels like a horror movie."

Mikey, however, grinned, turning in a slow circle. "Sweet! So this is what school is like!"

Before anyone could answer, alarms blared to life, red emergency lights flashing through the halls.

Raph groaned, already reaching for his sai. "Well, that's subtle."

Leo exhaled sharply before stabbing a nearby alarm panel with his katana, silencing the sound. "April's gotta learn the T-phones are for emergencies only."

Mari crossed her arms. "Seriously. I thought we agreed—life-threatening emergencies."

"Uh, guys?" Cat's voice was barely above a whisper. She pointed to the far end of the hall.

A woman stood there. Stiff. Unmoving.

Her head tilted unnaturally, her red-glowing eyes locking onto them.

Then—her voice crackled through the air. Distorted. Static-filled.

"A-A-April O'Neil?"

Raph tensed. "Ah, sewer bunnies."

Without warning, she fired.

Missiles launched from her elbows, rocketing toward them.

Boom! The explosion rocked the hallway, sending the turtles tumbling backward.

Mikey groaned from the floor. "Leo, I think this does count as a—"

"An emergency, I know!" Leo snapped, pushing himself up.

The droid moved like a spider, limbs bending at unnatural angles before launching forward.

Mari was the first to react. Her tantos flashed, blocking an incoming strike before she twisted, narrowly avoiding a counterattack.

The droid lashed out again, forcing Mari to flip backward, but its unnatural strength made it relentless.

Raph leapt in, catching one of its arms with his sai and twisting.

The droid barely reacted—instead, it used the momentum to hurl Raph straight into a trophy case.

Glass shattered.

Cat gasped, then lunged forward with her tessen, aiming for its joints. But the droid was too fast—it dodged, grabbing a folder from a nearby desk.

In one swift motion, it hurled the papers like razor-sharp blades.

Mari barely dodged in time, landing beside Raph. "I hate everything about this!"

Leo gritted his teeth. "All right, guys. Let's put old Mother Hubbard back in her cupboard."

Raph glared at him. "Dude, it literally hurts to listen to you sometimes."

The fight intensified.

Blades clashed. Sparks flew. The droid was relentless, its movements too calculated, too strong. It took everything they had just to hold their ground.

Then, in one clean slice, part of the droid's face was slashed away.

Everyone froze.

Metal gleamed underneath.

A Kraang insignia was stamped on the side.

Leo's stomach dropped. "That's... not human."

Mikey's eyes widened. "It's a Kraang droid—minus the Kraang."

The droid twitched, wires exposed, but still functional.

Leo's mind raced. They needed to disable it—fast.

His gaze darted toward the nearest water fountain.

"Mikey! The water fountain!"

Mikey blinked. "I know! School has everything!"

Leo groaned. "No—SPRAY HER!"

Understanding clicked.

Mikey lunged forward, slamming his hand against the button.

A jet of water erupted, drenching the droid.

Sparks flew, electricity crackling violently.

The droid convulsed before finally shutting down, collapsing with a heavy thud.

Silence filled the room.

Then—April peeked out from behind a row of lockers, scowling. She stepped forward and kicked the remains of the droid.

"And stay down!" she huffed. Then, crossing her arms, she shot them a glare. "Took you guys long enough."

Donnie dusted himself off, flashing her a small smile.

Mari rolled her eyes. "You are so welcome."

April frowned at the remains. "So... what the heck was that thing?"

Leo sheathed his swords. "It looked like a Kraang droid, but—without the Kraang."

April's brows furrowed. "She—uh, it—said it was from the Worldwide Genome Project."

Mikey, still holding the droid's synthetic face, turned it in his hands. "Whoa. How did the Kraang know you sent your DNA spit to the Worldwide thingamajig project?"

Cat yelped, kicking one of the loose droid limbs across the floor. "Creepy!"

Donnie's eyes darkened. "The Kraang must've hacked their system. Who knows what kind of information they could be stealing?"

Leo nodded. "April, you'd better head to the lair where it's safe. We'll go check out the Worldwide Genome Project."

Mikey, distracted, glanced at a poster on the wall.

"But first, we gotta take down the Eastside High Panthers. According to this poster, they've got it coming."

The city was quiet as the turtles moved across the rooftops, the cool night air rushing past them.

Unbeknownst to them, a figure followed in the shadows.

Karai.

She kept her distance, her gaze locked on them with sharp curiosity.

Down below, the darkened building of the Worldwide Genome Project loomed ahead.

Raph squinted at the entrance. "So, how do we get in?"

Donnie smirked, pulling out his T-phone. "Leave it to me. I've got an app for that."

Before he could do anything, Raph rolled his eyes and marched forward—then promptly kicked the door down.

Donnie sighed. "Or we could do that."

Inside, the air was thick with something... wrong.

Mikey wrinkled his nose. "You know, for a human lab, this place is awfully Kraang-y."

Leo's expression darkened. "Guys, I think the Kraang are the Worldwide Genome Project."

They moved cautiously through the dimly lit hallways, reaching the central lab.

At the center stood a massive tank filled with glowing, unnatural ooze. Around it, labeled containers lined the walls, each one filled with animal DNA samples.

Mari's sharp eyes scanned the labels. "This isn't just random." She turned toward Donnie. "They're collecting samples."

Donnie nodded, fingers tracing the lettering. "It looks like they're cataloging DNA from every plant and animal species on Earth."

Leo's stomach twisted. "Why?"

Mikey nudged Donnie. "Building blocks, dude. I'll drop the science on you later."

Before they could process it further, movement caught their attention.

Two Kraang droids appeared, weapons raised.

Before they could fire, Donnie struck first, knocking one back with his bo staff. Raph followed up, grabbing the other droid and shoving it into an empty containment unit.

Raph smirked, locking the door. "Now, you two play nice in there."

Silence.

Then—

"Gotcha!"

All heads snapped up.

Raph stood above the mutagen vat, holding a struggling Karai by the arm.

Leo's heart stopped. "Karai!"

Donnie blinked. "Ka-who?"

Mari and Cat exchanged confused glances.

Raph narrowed his eyes. "Bet you think you're pretty slick."

With a sudden, fluid motion, Karai twisted out of Raph's grip and flipped him onto his shell, pinning him down with her foot.

"I have my moments," she quipped.

Raph growled, immediately retaliating, their fight escalating into a flurry of movement.

Mari tightened her grip on her tantos. "Who is this?! And why is she kicking Raph's butt?"

Cat leaned in. "Should we... stop them?"

Leo's frustration flared. "Raph, Karai—stop it!"

Donnie looked between them, his confusion growing. "Okay, what the heck is going on here?! How do they know her?"

Mikey tilted his head. "Yeah, and how do we know her? Wait. Do we know her?"

Karai, ignoring them, turned her attention to the tank of mutagen.

"So, this is the stuff that turns people into monsters, huh?" She leaned forward slightly. "How's it work?"

Raph, still on the ground, sneered. "Why don't you lean in a little closer, and I'll show you?"

Karai smirked, knocking him back again.

Mari took a step forward. "Okay, seriously, are we not gonna stop her?"

Leo quickly stepped between them, raising his hands. "Enough! You're gonna set off—"

His elbow bumped into something.

A button.

A loud click echoed.

Raph groaned. "Nice going, Leo."

Leo stiffened. The tank began to hum.

Karai raised an eyebrow. "Huh. That can't be good."

Suddenly, the sound of approaching footsteps filled the air.

More Kraang.

Weapons raised, they surrounded the group from the catwalks.

A monotone, robotic voice rang out.

"The ones who are not authorized by the authority of Kraang to exist in this place will now be destroyed by Kraang in this place."

Karai's smirk widened. "This day just keeps getting better."

Without hesitation, she leaped into action, slicing through the first wave of Kraang droids.

Leo gestured wildly. "Look! See? She's on our side!"

Raph scoffed. "Are you even listening to yourself?!"

Mari gritted her teeth. "She's literally fighting us and them. What is happening right now?"

Cat, watching Karai fight, whispered. "Okay, but she's really cool."

Mari smacked her.

Karai twirled mid-air, landing next to Leo. "I like your brother, Leo." She flicked her sword toward Raph. "He's almost as entertaining as you."

Raph gritted his teeth. "Oh, when this is over, I'll show you just how entertaining I can be."

Before anyone could respond, the room shook.

A deep rumbling filled the space.

All eyes snapped toward the tank as the ooze began to shift.

Then—

The tank exploded.

Green mist filled the air as something massive rose from the swirling mutagen.

Tentacles slithered out first.

Then—armor plates.

Bat-like ears.

Jellyfish eyes.

The creature's massive head loomed over them, its long body writhing as it let out a guttural, ear-piercing screech.

Mikey's jaw dropped. "Aww. He's so cute."

The mutant's head shot forward, razor-sharp fangs bared.

Mikey screamed, jumping behind Donnie.

Cat shrieked. "WHY DOES IT HAVE SO MANY PARTS?!"

Karai, watching with wide eyes, grinned. "Whoa. That is wicked."

Mari grabbed her mask, muttering. "I'm gonna be sick."

Mikey gasped. "Oh, man, how am I gonna name this?!"

Before anyone could react, Karai swiftly grabbed one of the fallen droid heads and made her way to the window.

Leo gaped. "You're not gonna help us beat this thing?! It's your fault!"

Karai smirked. "I'll let the heroes handle it."

Leo's fists clenched. "I trusted you!"

Karai turned, amusement dancing in her eyes. "I know. That's messed up, right?"

And then, she was gone.

Leo felt something inside him crack.

A laser blast interrupted his thoughts.

The Kraang had turned their weapons on the mutant, firing round after round.

Raph scoffed. "So, guys, we all fans of Karai yet?"

Donnie, still processing, threw up his hands. "I don't know who she is, but I know I hate her!"

Mari, gripping her tanto tightly, growled. "Next time I see her, I'm slicing her in half."

Cat, still staring at the massive writhing mutant, whispered. "I mean, not to make things worse, but... why does it look like that?"

Raph shot her a glare. "Not the time, Cat!"

The hybrid mutant screeched, its massive tentacles slamming against the walls.

One struck Raph, coiling around him.

"Guys!" he choked out.

Mikey ran forward. "No, no! Call him 'Octo-Eyeball-Jelly-Bug'! No—wait—Justin! Let's just call him Justin!"

Justin roared, flinging Raph aside and electrocuting Donnie with an eerie blue pulse.

Mari barely dodged a swinging tentacle. "Okay—yeah! Justin's a menace!"

Cat was frozen for just a second, watching Donnie convulse from the shock. Then, her fists clenched. Without thinking, she sprinted forward, dodging Justin's tendrils as she grabbed Donnie, trying to pull him away.

"Donnie, get up! Get up!"

Leo stood frozen, watching as his siblings struggled.

"Raph was right." His voice was barely a whisper. "This is my fault."

Then, his eyes blazed.

"HEY, JUSTIN!"

The mutant turned.

Leo charged.

Dodging every tendril, he leaped onto its back, katana flashing. He struck—again and again—until he reached its head.

Electricity sparked around him.

"This ends now!"

He lifted his blade—angled it.

Then—he struck.

The blade plunged into the containment unit's core.

A high-pitched screech ripped through the lab.

Then—

An explosion.

The force sent them flying as the entire building shook.

Justin collapsed, slamming through the wall.

Smoke filled the air.

Leo coughed, forcing himself up. "Come on! We have to get out of here!"

Mikey stumbled forward, dazed, as Cat steadied him.

Mari narrowed her eyes at Leo. "we're thinking somebody should start talking."

Leo stood in the center of the room, shoulders tense, guilt pressing down on him like a weight too heavy to bear.

The others stood around him—watching, waiting.

Leo took a slow breath. "I should've told you about Karai sooner," he admitted, voice low. "But I really thought there was a chance she would be good. And I guess... I sort of liked her."

His jaw tightened as he braced himself. "Go ahead. Laugh."

No one did.

Mikey crossed his arms, his usual lightheartedness gone. "Dude, I can't believe you trusted her." His voice wasn't teasing. It was genuine. Hurt.

Donnie's frown deepened. "I can't believe you didn't trust us enough to tell us."

Mari sighed. "Dumbass."

Cat was frowning. Her silence scared Leo.

Leo exhaled sharply, the guilt twisting. "I was wrong." He met their eyes, sincerity in his gaze. "I'm really sorry."

April, arms crossed, shook her head. "I tried to warn him."

Raph let out a dry chuckle, but there was no humor in it. "You too, huh?" His voice was edged with frustration.

Then, Splinter stepped forward.

"Leonardo," he began, his tone calm—but firm. "You are not the first young man—or turtle—to make a fool of yourself over a girl."

Mikey, seizing an opportunity, gestured wildly. "What about Donnie?"

Donnie shot him a glare. "Not the time, Mikey."

"However... when that girl is a Kunoichi in the employ of your enemy, that is an error you cannot afford," Splinter contiuned.

Leo's chest tightened, but he nodded. "Hai, Sensei."

Splinter's eyes darkened. "Deception is the ninja's most powerful weapon," he continued, "and it seems Karai is a master."

Leo swallowed hard. "I know." His voice was barely above a whisper. "We can't trust her. I see that now."

Splinter studied him for a long moment.

Then, with the slightest nod, he spoke. "Good. You must learn from your mistake."

Relief flickered in Leo's chest. "Thank you for understanding. I'm glad you're not mad."

Splinter stilled.

Something in the air shifted.

Leo barely had time to process it before—

CRACK!

Pain shot through his leg.

Leo yelped, stumbling back, barely catching himself.

Splinter's voice was sharp—unforgiving. "Who says I'm not mad?"

Silence fell over the room.

Leo swallowed thickly, heart pounding in his chest. He nodded quickly, forcing himself to stand straight despite the throbbing pain.

"Hai, Sensei."

Splinter didn't say anything else.

The weight of his disappointment hung heavy in the air.

With that, Leo turned and made his way to his room, the pain in his leg barely a fraction of the shame burning inside him.

Mari followed a second later, not looking at anyone.

Leo barely made it to his room before he heard footsteps behind him.

Raph.

Leo didn't turn around.

"Hey, bro." Raph's voice was quieter than usual. "I'm glad you came to your senses."

Leo let out a humorless laugh. "You were right." He exhaled. "I don't know what I was thinking."

Raph leaned against the doorway, arms crossed. "Well... I can see how you'd think she's hot. In an evil kind of way."

Leo finally turned, giving him a dry look. "Yeah. Well, don't worry." His voice was tired but firm. "I am so over that."

Raph smirked slightly. "Good."