Chapter Text
The city never slept, but tonight, even its usual hum seemed quieter—muffled by the cold air, heavy with silence and a biting chill. Leo sat hunched on the edge of a rundown rooftop in Brooklyn, fingers curled tightly into the sleeves of his blue hoodie, shivering with each sharp gust of wind that blew past the perch. His breath came out in pale clouds, disappearing into the darkness.
His shoulders ached—not from battle or from training, but from carrying too much .
The slider rubbed his hands together roughly, trying to summon some warmth, though it felt more like a distraction from everything else. He pulled the fabric down farther, trying to cover the fins that jutted out from his forearms. The sight made his gut twist. He clicked his tongue in frustration, eyes narrowing.
He hated them.
He hated this .
The fight with Raph echoed fresh in his head, sharp and raw, the words ringing louder than the cold ever could.
"How are we supposed to be heroes when you’re over here looking like a monster? "
Leo flinched.
Monster.
The word bounced around in his chest like a ricocheting blade, carving itself into every soft part left inside him.
He stared at his hands, the faint shimmer of webbing between his fingers catching the distant glow of a neon sign. His gaze drifted lower—his tail gave a slow twitch on its own, like a serpent tasting the air. It didn't feel like part of him. It never had. Just another thing he couldn’t control.
Just another reason to agree with Raph.
"Monster."
A groan tore from his throat as he dropped his head into his palms. His fingers curled against his jawline, wishing— wishing —he could peel it all off and go back. Back to when he was just Leo, the cocky one, the funny one, the one who didn't have to lead anyone or carry a curse in his veins.
This wasn’t his fault. It wasn't . He just knocked over a stupid vase. That’s all it took. One dumb mistake in some museum, and now…
Zarynthia.
Even her name crawled through his thoughts like ice.
He could still hear her, sometimes, slithering through his mind when he tried to sleep—her voice sweet, but coiled with venom:
"You are mine now, little leader."
"No one will understand you. Not even your family."
Leo clenched his jaw, shaking his head as if he could toss her out like water in his ears. But her whispers never left for long. He was haunted , and worse—he was cracking under the pressure. Two weeks in, and it already felt like he couldn’t breathe.
Too many expectations .
Too many changes .
Too much.
Leo let his arms drop, leaning his shell against the rusting AC unit behind him, gaze cast toward the starlit sky above the towers of Manhattan. His voice was barely a murmur, lost to the wind.
“This sucks…”
He crossed his arms tightly over his clothed plastron, the fabric of his hoodie pressing awkwardly against the rise of newly developed fins on his arms. His tail thumped once against the rooftop, as if echoing his bitterness.
He hated that he ran.
But how could he not?
When every look from his brothers held worry or fear, when even Splinter didn’t have answers, when he didn’t even recognize himself in the mirror anymore… what else could he do but escape?
Stillness settled over the rooftop. Distant sirens wailed, a dog barked three blocks down, and the hum of the city slowly returned to his awareness. But Leo remained unmoving—shoulders curled inward, alone with the cold and the stars.
He should head back home, it’s been an hour already and surely they must be wondering where he went off to. But Leo didn’t really want to go. Not yet. Not when he just knew he was going to be smacked with more arguing when he returned, and quite frankly he simply didn’t have the energy to face that right away.
He sighed and reached for his swords, fingers brushing their hilts like old friends.
“Hm… maybe a trip to Hawaii would do me good.” He tried a grin, weak and crooked. “Catch a wave, drink a coconut… get sunburned in five seconds flat.”
The joke fell flat in the silence, but it was enough to get him moving. He rose to his feet, brushing dust from his knees as he took a breath, focusing his mystic energy. He’d gotten better at this. Not great, but passable. He just needed a clear mental image.
“Only one way to find out. Hawaii, here I come.”
Leo lifted his katanas, twirled them with flair, and slashed the air in front of him. A glowing, spiraling portal burst to life with a familiar whoosh . The cool blue light flickered over his green skin and hoodie as he stepped up to it with a proud whistle.
He took a step through, grinning—
And immediately started falling.
“WAAAH—!”
The drop wasn’t long, but it was jarring. He slammed down on his side with a whump , groaning as the air rushed out of his lungs and left him breathless. Somewhere, something clattered and someone shrieked.
“Nardo?!”
Leo blinked, dazed. That voice…
Wait.
“Aw, man…” He muttered from his position on the floor, rolling onto his shell and groaning. “Did I seriously portal myself back ho—”
He froze.
Standing across from him, framed in the violet glow of flickering lab lights and surrounded by scattered tools, was Donatello. But not his Donnie.
How did he know it wasn't his Donnie? This Donnie had wings that flexed as if they would react to the sudden disturbance. A spiked tail coiled behind him, and his markings were different too, extra stripes on his face and arms.
Both turtles stared at each other like they were seeing an alien.
Leo slowly straightened up from the floor, his brain scrambling to catch up. And then, without thinking, he blurted…
“Since when did you get wings ?!”
Donnie gaped and snapped into action, eyes darting from Leo’s tail to the webbing between his fingers. “Since when did you get a tail ?! And are those fins ?!”
Leo instinctively wrapped his arms around himself, trying to hide the offending features. “It’s a curse , okay?!”
Donnie threw his hands up, and when he paid closer attention to them, they had much longer claws. “I didn’t say anything!”
With panicked breaths, Donnie fumbled over his cluttered work desk, scanning his eyes over the messy space to look for his cloaking brooch, “Wait, don’t look at me! This is- it's just a costume for the next Comic Con!” He frantically shouted out. Leo squinted at him doubtfully, before this cosplay version of Donnie eventually grumbled under his breath, exhaling and then giving in.
“Ah, pizza supreme, I’ve already been spotted.” He pouted to himself, shaking his head and clearing his throat before warily eyeing Leo who scratched his head in utter confusion, observing Donnie.
— ⋯ —
Donnie clenched his fists and crossed his arms in an attempt to hide the way they trembled from Le— no, the intruder, if there was any facade he wanted to maintain the most in this moment, it was his emotionless one.
The moment an unidentified person fell through a suspiciously familiar mystic blue portal, was the same moment his gut dropped and proceeded to roil with internal panic. He wasn't supposed to let anyone see him like this! Let alone one of his brothers, no one in his family knew about the secondary mutation, and he was determined to keep it that way.
Staring at the wide-eyed turtle, laying stunned on the floor of his lab, he can kiss goodbye to that notion.
Donnie drew out a silent breath, eyebrows drawing down and wrinkling his snout. He narrowed his eyes, taking this time to analyze the sudden and ungraceful appearance of what he can only assume is his twin brother.
He’s been discovered, ambushed in his own lab! By a Leo that looks like Leo, but simultaneously not . And worst of all, he’s uncloaked and visible . The brooch was recently lost within the scattering of knickknacks; Donnie had taken it off when he needed a reprieve from its side effects, and had assumed he could easily find it again later. Curse his messy lab! He’s been meaning to tidy it up for 2 weeks now, but kept putting it off in favor of using that time to multitask between projects left half unfinished, ones that had taken up any and all available flat surfaces.
Maybe he can salvage this situation, the intruder hadn’t run screaming in fear or panic yet, so… when in doubt, data collection!
Donnie knew he saw Leo only a few hours ago, and he was definitely sure that he hadn’t changed all that much in such a short time frame. This Leo had wholly different markings all together, extra stripes on his face, his eyes slightly different, and he definitely recalled how the Leo he saw before didn’t have a tail or fins nor resemble a fish with a turtle shell.
“Gasp, could it be…?” He mumbled, humming in curiosity. He released one of his arms from its tensely folded position and tugged the goggles on his head down over his eyes, leaning in close as the programmed software he designed in the goggles did the rest of the work, scanning Leo’s body like a vulture observing its prey.
— ⋯ —
“Uh…?”
Donnie moved forwards and circled him a couple of times, even grabbing Leo’s arm and lifting it up to his eyes, then poking at the tail that twitched at the sudden contact.
“Fascinating… somehow your entire physiology is completely altered. Even your signature is different!”
Leo watched him, puzzled by what he was going on about, “You care to fill me in, Dee?”
Donnie stepped back, pulling his goggles up to rest on his head as he clasped his hands together. “Judging from, uh, well… everything, you are not the Leo that I’m familiar with. Your whole signature—according to the data I received from my goggles, is different. It’s like you have something else in you.”
Leo felt the beginning of a nervous sweat beat on his forehead, chuckling awkwardly. That was to be expected considering he did have something else in him, literally.
The two stared at each other for another beat of baffled silence, breaths heavy and uneven.
“…So,” Leo finally said, adjusting his hoodie, “This isn’t Hawaii.”
Donnie’s brow twitched. “ No , it is not. But it’s also not your home dimension anymore either.”
Leo’s eyes widened slightly. “Wait. Dimension ?”
His face twisted in utter bewilderment, he even swore he could hear the gears turning in his own head, mouth slightly hung open, as one hand pressed up to his temple as he tried to process the nerdy words he just heard come out of Donnie’s mouth.
What did he mean by that?! Was he being played?! Was Donnie twisting his arm—
Donnie’s wings drooped a little as he pinched the bridge of his snout. “You must have made a dimensional jump. Your mystic abilities must be… horrifyingly unstable.”
“Rude.”
Donnie jabbed a finger at him. “ Accurate .”
Leo narrowed his eyes, crossing his arms but tilted his head briefly, watching Donnie. Taking in his appearance. Large wings that could easily shield him if Leo stood behind them, his tail curled tightly around his feet where he stood, and while it wasn’t like Leo’s, the slider at least saw some sort of similarity between him and this strange looking soft shell turtle that resembled his brother. He still had the same purple bandana, same fancy shmancy wrist tech and goggles, same haughty air to his expressions. Just now with… extra features?
With a scoff of ignorance, Leo grinned, eyeing the purple clothed mutant. “So, what were you hit with? Did you get combined with a bird? No, wait, wait! Don’t tell me, scorpion, right?”
He moved a little closer, throwing his hands out dramatically, walking behind Donnie and unable to resist the urge to reach out and touch the feathers, ignoring the way Donnie shuddered and flinched at the sudden sensation of someone feeling his wings.
“Hey!”
“Wow, did myself from this dimension seriously let you leave the lair like that? Or wait , did you decide to Frankenstein yourself—“
Donnie groaned, rolling his eyes as his wing rose and flicked out to whack Leo away, imitating a slap of sorts. Which, ow, that was kind of strong. He then tucked both wings behind himself as much as possible and out of reach.
“Excuse you, don’t you know it’s rude to touch people without consent first!”
Leo held his hands up, mocking surrender as he backed up, trying not to laugh when he realised how ridiculous those words sounded when taken out of context. “Okay, okay. Yeesh , hit a nerve or something there?”
But Donnie didn’t reply, and instead they both paused in semi-awkward silence. Leo found himself glancing around the lab, noting the different tech, the subtle color palette differences, the slight wrongness in the air he could feel now that he focused on it. He looked back at this other Donatello—one who… didn’t know about the Sea Serpent goddess or the vase, or actually any of it. Huh.
Leo blew out a long breath. “Okay. This is fine. Not a total disaster.”
“You crashed through your own portal into my world.” Donnie deadpanned, making Leo wince before chuckling as he waved off the comment.
“Okay. So, a slight disaster.”
Donnie crossed his arms again. “What were you trying to do?”
“…Vacation.”
Donnie blinked owlishly.
“Vacation…” He repeated, in a tone that read, ‘ that is the dumbest thing I’ve heard all week.’
Leo gave him a sheepish grin, tail flicking behind him like a guilty cat.
“Well…” Donnie sighed, already rubbing his temples. “I guess since you're here… you could tell me what the hell happened to you. And I could help you try and get home. And do not touch anything .”
Leo raised his hands in surrender. “Scout’s honor.”
“You weren’t a scout.”
“I was a Todd Scout. It definitely still counts.”