Michelangelo takes a staggered step backwards, his hands trembling as he keeps them held up in front of him. "Don't do it, Bebop," he says, unable to look away from the retro-mutagen aimed at him, unable to think of anything more than how much he doesn't want to be a regular old turtle again.

Bebop oinks, stamping his foot against the ground. "Stop calling me that name, fool! I hate that name! I hate that name!" He lets out a sad sob for a moment before it dissolves into maniacal laughter. His finger slips to the trigger. "Time for the next mutation, turtle."

Michelangelo whimpers as Bebop applies pressure. For a split second, there's utter silence, and then it's shattered by Leonardo's voice.

"Mikey!"

Leonardo leaps down, trying to slice the retro-mutagen from Bebop's hand, but Rocksteady intervenes before he can even nick the canister. Michelangelo bolts.

"Nyet!" he shouts, knocking the turtle from the air and sending him sailing into the ghost house. Leonardo groans and Bebop prepares to shoot him only to have Rocksteady tug his hand down. "Bebop, wait. Think with the brain for once. Retro-mutagen can turn us human again," he explains, an edge of urgency in his tone as he taps his forehead.

"Wow, I didn't even think of that! Let's do the dizzle!" the warthog says. His face falls into a frown and he jabs an accusing finger at the lumbering rhinoceros. "And stop calling me Bebop, yo!"

He aims the nozzle towards himself as if preparing to put on perfume, but Rocksteady's beefy hand snatches it away.

"Nyet. Why do you get to be using it?"

"You did not just—"

"Give it back!"

"I had it first!"

"Nyet, nyet, nyet!"

They keep tugging at the precious resource, literally butting heads. Nearby, Leonardo and Michelangelo converge behind a row of trash cans, unable to do much other than watch the mutants nearby shriek and clamour at one another.

"We need a better distraction," Leonardo utters.

"Yeah, but what? The other half of our team is gone," Michelangelo whispers.

Karai and Destiny appear as if out of nowhere, dropping down in front of Bebop and Rocksteady. Karai hisses and Destiny snarls, her furry shoulders heaving, and both mutants stop quarrelling over the retro-mutagen for a split second.

"Huh?" they mutter.

Karai unleashes a spurt of venom into Rocksteady's eyes, making him yelp and drop the retro-mutagen. He stumbles back blindly, crushing the jar in the process, and she hisses and launches herself at Bebop, making him scream too as she knocks him to the ground. With both of them momentarily subdued, the elusive mutant disappears around a corner.

"Get back here, snakey snake!" Bebop shouts, chasing after her with his lasers flying.

Destiny dashes to the van, ripping the door open easily before switching back to her normal form. Leonardo and Michelangelo appear behind her. April grins.

"Guys!"

"Sorry it took so long, April," Leonardo apologizes, helping her sit up. "I'll have you free in no time."

He cuts the glue bindings off of her as Destiny tugs Donatello up, placing a gentle hand on his shoulder as he winces. He blinks a few times, rubbing his head.

"Thanks, Des," he mumbles.

"No problem."

"Oh, my aching brain," Raphael groans, also holding his head as he hops out of the van. "What hit me?"

"It was that huge rhino dude," Casey says, looking around at the deserted amusement park. "Right there!"

He points at Rocksteady just as the mutant gets up, groaning and blinking his tiny eyes rapidly. A golden ring from one of the hoop toss games hangs around his horn. He looks up, noticing the escaped captives.

"Turtles...free?"

He roars, steam coming from his nostrils as he charges at the group. Destiny morphs into a wolf just as he's about to ram into her, taking the impact head on and slowing him down noticeably as they skid across the boardwalk. She rakes her claws along his leathery skin, shoving against him with all her might as he bellows.

"Wolves-girl make big mistakes!" he rumbles, trying to grab the giant beast.

She doesn't respond. She manoeuvres out of his grip and growls, her hackles raising as she prepares for another attack. The turtles, April, and Casey look to Leonardo, their eyes wide.

"What do we do, Leo?" Donatello asks.

"You three go after Karai," Leonardo orders, pointing to the two humans and his brother. "Me, Raph, and Mikey will take Rocksteady." He turns to his half of the team, katana ready. "Get him away from Des!"

Raphael and Michelangelo nod, taking Raphael's dose of retro-mutagen and hopping in front of the duelling pair of mutants.

"Hey, rhino man! You want some retro-mutagen?" Raphael taunts, waving the canister around.

Rocksteady snorts and turns on the two brothers. They laugh and rush away towards a looming rollercoaster, effectively getting him to chase after them. Leonardo drops himself next to Destiny as she switches back to her human form, kneeling against the boards as she tries to catch her breath.

"Shell, I'm totally going to bruise later," she mutters. She looks around, her pupils dilating. "Leo...where's Diaval?"

Leonardo's face slackens and he too scans the immediate area. "Shell..." he mumbles.

"Leo—"

"Des, he'll be fine. Our priority now is to get Bebop and Rocksteady off our tails," he interrupts. He stands, offering his hand to her. "Are you ready?"

She hesitates before she takes his hand, letting him pull her to her feet. "Yeah. I was born ready."

They dash off at full speed towards the rollercoaster.

----------

Donatello and April stare up at the ghost house warily. Casey, on the other hand, cracks a grin.

"Whoa, wicked. This was my favourite funhouse as a kid," he says, flipping his mask down.

Donatello and April don't input their two cents. Instead, they just walk up the steps and go inside. Casey grips his hockey stick and follows. Inside, they take baby steps around, eyes darting to every corner and to every noise.

"Careful. He's close," April whispers as she feels her spine tingle. "Invisible. He's—"

A loud cackle sounds as an orange sludge monster appears in front of Donatello, making all of them scream.

"Oh, I hate that! I hate it when stuff jumps out at you!" Donatello complains, stomping his foot.

An invisible force smacks him into a wall as a voice comments, "I know exactly what you mean."

Casey gasps and scoots backwards, hockey stick held up and ready, but the invisible warthog is too stealthy. There's a snort right before the weapon is whipped from Casey's hands.

"Hey!" he shouts. In the next second, the stick smacks him. "Ow!" April inches away from him, completely on edge.

"Don't worry. I would never hit a lady," Bebop says. April yelps as her legs are knocked out from under her and she lands on her back. "But I'll trip her."

----------

"Come out, lowly cowards!" Rocksteady taunts as he nears the rollercoaster.

"Come and get us, Rocksteady!" Michelangelo retorts as he climbs the wooden structure of the ride.

"Hey, Rocksteady. Looking for some retro-mutagen?" Raphael teases, waving the canister around.

Rocksteady snorts and starts climbing the coaster. The two turtles get onto the tracks, and Raphael sends the vial soaring through the air. Leonardo appears and catches it with ease before touching down on the tracks. Rocksteady roars as Destiny makes it onto the ride as well.

"All aboard the turtle coaster!" Michelangelo shouts, whipping a shuriken at the control panel. There's a buzz and a clanking noise before the coaster starts up.

The three turtles and Destiny race towards the ride carts and hop in, Rocksteady giving chase after them. The rhino snorts and puffs as he tries to keep up. The line of coaster cars reaches the peak of a giant drop and four mutants only have time to gasp before rocketing downwards.

"WHOOOOOO!" Michelangelo and Destiny scream, throwing their hands in the air as the cart weaves and twists and turns.

Leonardo turns around from his spot in the first cart, his eyes widening as their enemy advances. "Here he comes. Doesn't this thing move any faster?"

Michelangelo leaps to the last cart and smacks Rocksteady with his nunchucks, but the weapons have little effect on the rhino. The Russian mutant smacks the smaller turtle, almost making him fall off the cart, and Michelangelo squeaks in terror at the close call as Raphael pulls him back up into the second cart.

Just as Rocksteady climbs into the back of the coaster, Leonardo snags a loose piece of wood and whips it at him, nailing him in the face. He goes sailing off the coaster and rolls away, the carts chugging away.

They round the corner only to run into Rocksteady again. He snorts and smashes a long staff of wood into the coaster, derailing the carts and sending each of the mutant teenagers inside flying. The turtles deploy their grappling hooks, which loop around the wooden beams holding the coaster up.

Destiny, on the other hand, has no grappling hook to stop her fall. She lets out a scream as she plunges towards the earth, her heart pounding. Just before impact, Leonardo and Raphael swoop down and each grabs one of her forearms, swinging back towards Rocksteady with Michelangelo close behind.

"Eat it, rhino!" Raphael shouts.

They nail him in the face with well-aimed kicks before swinging past, but Rocksteady spins around and snags Michelangelo by the back of his shell. He yelps as his advance halts.

"Mikey!"

Rocksteady backs up. "You will give me retro-mutagen now!" he demands, holding Michelangelo up like he's some sort of prize.

Leonardo fully grasps Destiny's hand and swings her over into his arms as the trio lands back on the coaster, hanging off the sides by their grappling hooks. They stare at their enemy as he dangles Michelangelo above the dizzying drop off the edge of the coaster.

"Turtles, give retro-mutagen," he repeats.

Michelangelo screams and flails in his captor's iron grip. Leonardo, who still holds the retro-mutagen in one hand while his other arm remains secured around Destiny, heaves a long sigh.

"Leo, we need it for Karai," Destiny whispers, her hand drifting to his plastron.

He doesn't register any emotion. "Trust me. Now hold on."

She wraps her arms around his neck without objection. Leonardo leaps off his current nook and lands on the track in front of Rocksteady, leaving a generous distance between them. He sets Destiny down and raises the retro-mutagen.

"Put him down first," he orders, his voice deep and commanding. "I don't trust you."

"I has your word you give?" Rocksteady asks.

"You has my word," the turtle promises.

Rocksteady snorts and brings Michelangelo away from the drop, and with a smirk, throws him towards the awaiting teens. He lands on his face, almost slipping back down the coaster before Destiny grabs his hand.

"Ugh. Thanks, bro," he mumbles to Leonardo. Destiny pulls him up and he hugs her tightly, making her eyes widen. "I saw my life flash before my eyes. So much pizza..."

She manages a small smile as she gently strokes his head. He releases her and grins, turning back to face Rocksteady. Leonardo still holds the retro-mutagen, the wind whipping his mask tails back as he glares ahead.

"Retro-mutagen now!" Rocksteady booms.

"You want it? Take it!" Leonardo shouts, throwing the canister as far as he can.

The Russian mutant reaches out for it as it pinwheels through the air, but Raphael swings by and snatches it just as it's about to reach the rhino's hand.

"No! You gave word!" Rocksteady shrieks.

"But I didn't!" the red-masked ninja returns.

He tosses the retro-mutagen back to Leonardo as him, Michelangelo, and Destiny take off running again, leaping down the tracks. The turtles release their grappling hooks and swing off into the air as Destiny keeps running. She glances behind her, seeing Rocksteady still giving chase, and she runs a little faster. He whips out two golden sickles and throws them, the shining weapons acting as boomerangs.

"Oh no," Leonardo groans as one cuts through his hook string.

He lands in the rollercoaster cart as it moves along the tracks directly towards Rocksteady. The rhino grins widely and Leonardo scrambles to his feet in search of an escape route.

"Hey, horn head!" Raphael shouts.

"Booyakasha!" Michelangelo whoops.

They both swoop at their assailant, but he grasps their feet and absorbs the impact of their oncoming kicks. They both gasp as he roars and shoves them back the way they came, their hooks tangling as they smack into one another.

Rocksteady snorts and stomps around, searching for the retro-mutagen and the turtle who last had it. Above him, the rollercoaster cart appears with Leonardo and Destiny inside, matching devious grins on their faces. The cart passes the peak and plummets.

"Rocksteady! Eat it!" Leonardo shouts.

The cart train rams right into Rocksteady. He goes flying through the air, all the way back to where Bebop is fighting with Donatello, April, and Casey. The heavy rhino smashes into the warthog and sends the two crashing into their van, knocking it over with a heavy groan.

Silence falls for a brief second.

"Everyone okay?" Donatello asks as he gets up.

"I think I only sprained a leg or two," Casey says, flashing a weak grin.

The two groups converge just outside the funhouse, sharing only the briefest of greetings and confirmations that they're all okay. Destiny sniffs the air, her tail lashing to and fro as she looks about, never sticking to one spot for too long.

"Karai, I know you're here," Leonardo calls. "Come out. You don't have to be afraid anymore."

They go quiet. Nothing happens for a long moment, then Destiny's ears swivel as she detects approaching footsteps. It's accompanied by soft hissing. She turns just in time to see Diaval and Karai emerge from behind the funhouse: Karai remaining submissive and keeping her head down, Diaval looking blank-faced as ever.

"Diaval, oh thank goodness," Destiny whispers, hurrying over to him. She stops right in front of him and flashes a tiny smile. "You're okay?"

He nods. "Got away from fight," he says. "Found Karai. All good."

Karai nods as her forked tongue flicks between her lips. Leonardo steps forward, his grip firm around the retro-mutagen gun, and the three of them look over at him.

"We can help you," he says, his eyes only on Karai. He smiles and gestures to the retro-mutagen. "With this."

She lowers her head even more. Diaval and Destiny back away and Leonardo pulls the trigger. There's a low hiss as an orange cloud of retro-mutagen covers Karai, obscuring her from view, but when it clears, nothing has changed. She's still a snake.

"It doesn't work," Leonardo says. His voice hitches with panic. "Donnie?" He faces his brother as the purple-masked turtle inches closer.

"I told you, Leo. Karai is special," Donatello utters. His russet eyes are sorrowful. "She's not a normal mutant. She can shift forms, it changes the way her body reacts to it."

"It was all for nothing?" Raphael asks. His shoulders slump and he flinches, reaching one hand up to grip his aching muscle.

"It doesn't matter," Leonardo says. He walks right up to Karai, arms held open. "You can come home with us, Karai. We'll take care of you, I promise."

"No..." she says softly, her face agonized. "Too dangerousss." For a moment, Leonardo doesn't say a word. His heart pounds and he feels his eyes itching. "My mind isss going," she continues, unable to even look at them.

"Then...then why did you want us to find you?" Leonardo asks, his tone broken.

"Wanted to say...goodbye...to all of you," she whispers.

She turns to go, but Destiny dashes forwards and takes her arm gently. Karai meets the girl's eyes with shock and confusion. "Karai, I know what fear can do to a person," Destiny says, not yet releasing the snake girl from her grip. "It consumes you. It...it ruins everything that's good in your life if you let it control you, but you have a chance. It will get better, but...only if you let your family help you." Her voice is pleading and soft, not to mention completely sincere. Everyone watching is stuck in stunned silence, their mouths slightly agape. "Karai, please, these," she says, gesturing to the nearby turtles and, subsequently, Diaval, "are your brothers. We're your family."

Karai lets out a soft hiss and pulls her arm away as Destiny slackens her grip. She places that same hand on Destiny's shoulder and two pairs of wild, hurting green eyes meet one another's, and there's a brief moment where hostility has vanished and there's only mutual empathy.

"I'm...sssorry. For everything..." she murmurs.

Karai turns and sweeps over the railing and into the water of New York harbour, disappearing from sight. Leonardo sprints after her, crying out "no", but it's too late. He stares into the dark water, his expression too complex to describe.

"Karai!" he calls. When there's no response but rippling waves, he sighs and steps back. "We'll figure out a way to help you, Karai. I promise."

Destiny doesn't move, wrapping her arms around herself and staring out at the darkened sky. Michelangelo sniffles and rubs one eye, heartbroken. Diaval's hands clench into fists and his chin dips down to his chest, his bangs covering his eyes.

"Guys, Bebop and Rocksteady are gone," April comments, breaking the silence.

"Ah, let them go. The next time I see them, they won't walk away," Raphael promises, although his tone lacks anything threatening or even angry.

Leonardo looks to Destiny, whose head is drooped with her hair hiding her face, and he takes hesitant steps toward her. When she doesn't acknowledge his presence, he reaches out and cups her face in his hand, lifting it. Her eyes glisten with held back tears.

"I'm sorry, Leo," she croaks out. "I tried...but...I-I just failed you again."

"Oh Des..." He shakes his head and brings her into a gentle hug.

She shuts her eyes and buries her face against his shoulder, her fingers tightening around the sheaths strapped to his shell. He kisses the top of her head, right where her hairline meets her forehead, and his eyelids slide shut as they inhale and exhale as one.

"I'm proud of you."

She buries herself in his embrace further, a few tears slipping down her scarred features. Casey smiles faintly at them before averting his gaze to the rest of his friends. Diaval stares out at the water, the moonlight illuminating the dampness of his cheeks, and his lips move as he murmurs something to the waves that no one can quite catch.

"Come on, team," Michelangelo says, his smile absent. "Let's go home."