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Language:
English
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Published:
2025-03-19
Updated:
2025-09-06
Words:
75,428
Chapters:
40/?
Kudos:
27
Bookmarks:
2
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1,251

2012 / ROTTMNT / TOTTMNT One-Shots

Summary:

!!OPEN REQUESTS!!

Mostly human rat mutant, affectionately named Yuji by Splinter, joins the turtles in varied journeys to discover the secrets behind his odd mutation.

Notes:

!!HURT/COMFORT!!
- The cutesies

Chapter 1: 2018! 🆔 Soft Shell

Summary:

The turtles have captured a new supposed criminal, a boy with rat-like ears and a tail. He’s heavily involved with an underground gang. He was entrusted to Donatello as a hostage to track the gang itself down— it doesn’t exactly go as planned.

Notes:

!!FLUFF!!
- Needles and blood warning!

Chapter Text

Muscles weak, mind fading in and out from consciousness, ears pinned down, Yuji rested against the cold floor. He knew he’d been captured by some do-good turtle mutants during one of his gangs typical distraction crimes. They’d start one illegal operation, sacrifice the members involved, then complete the true objective.
Yuji lashed his tail. He could feel the chains binding him starting to bruise his wrists, though he wasn’t about to put up a fight. He’d been captured, that was on him. He doubted the gang would even search for him.

“Oh, great, he’s awake.” Grumbled a voice that Yuji barely recognized at first. His vision gradually focused on the turtle mutant that had successfully taken him down. He assumed he was trapped in said mutants lab.
The sarcasm was quite funny, though. Yuji rested against the floor, content with the cold feeling against his loose and sore muscles. He shut his eyes and accepted whatever may come his way.

“Donnie? Are you safe?” Another voice poured out from what appeared to be a cellphone.
The mutant dawning a purple headband nodded with a roll of his eyes. “Yeah, yeah. He’s drugged anyway.” His disinterested tone registered Yuji as an insect-level threat.
Relief panned over the call, thanking Donatello for his help and wishing him luck with Yuji. The voice demanded that he be notified if the gang came to take Yuji back.

Donatello was quick to brush him off and end the call. He set his phone aside. As he turned, facing a small spread of glass beakers filled with various different sedatives, Yuji noticed something— his shell was almost entirely translucent. At least, he could vaguely trace his vertebrae through the smooth surface of it.
With his back turned, exposing a weak point, Yuji hummed. His rat tail extended towards the shell. However, he was oddly gentle as he ran his tail along it, feeling its rubbery and smooth texture. Yuji’s rat ears perked and flicked. He’d never seen anything like that.

“I feel that.” Deadpanned Donatello, flicking the end of a needle, watching some liquid spurt from the syringe.
Yuji withdrew instantly. His ears perked up, eyes focused on Donatello’s spine. “Really? I’ve never seen anything like that.” He confessed.
Donatello huffed as he turned towards Yuji, crouching before him with the syringe in hand, possibly containing more muscle relaxants. Yuji’s ear twitched. “Stay still.” Demanded Donatello.

Yuji obeyed. He didn’t find it hard to comply with Donatello’s demands, especially because he was getting a relaxed experience out of it. He could barely feel the bruising staining his wrists with how much sedative he’d been given. He shut his eyes and hummed.

The needle approached his inner elbow. Yuji admired Donatello’s steady hand, although he doubted he should be so trusting. Needless to say, he was correct. A rift seemingly between worlds tore open, ripping right through the lab, revealing familiar members of Yuji’s very own gang. How they mastered this art was beyond him.

Their knives were aimed directly at Donatello’s back. With his shell, their hits would either paralyze him or kill him. Yuji was shocked that he grew horrified at that thought. His wrists yanked against his restraints, though with no time, he had to act. He scrambled, muscles weak from sedative, hurrying to crash into Donatello.
The two landed aside. The gang members skillfully rolled aside, saving themselves from an embarrassing tumble. Yuji lashed his tail. If Donatello’s shell was too soft, he’d just have to act as a hard one. Yuji guarded Donatello.

“Get off—!” Demanded the fellow mutant.
Yuji nodded slowly. He spun to his feet, muscles finally restored to their original power, tail flicking elegantly as he rose to his full height. His expression rippled with anger. Ears perked and surveying the area for more rifts of some sort, Yuji stood before Donatello, shielding him from harm.
The gang members, four in total, exchanged confused glances between one another.

Yuji huffed, “Shoo, you nasty things.” He demanded. Using his tail as a whip, he herded the members back to the rift which they came from, forcing them through it with a brief sigh. As the strange method of teleportation shut, Yuji stepped back, body reeling from the sedatives.
Donatello did nothing to study him. He simply allowed Yuji to sink to the floor, unbothered as he hurried to retrieve his shell shield. He’d rather not get caught like that again.

“Hm,” Yuji lifted his head. He offered his arm to Donatello, prepared for another sedative. “Are you alright?” He questioned. His voice was embarrassingly soft.
Donatello scrutinized him under a harsh and squinted gaze, “Yeah. You’re not gonna be, though.” He prepared yet another syringe.

Yuji flicked both ears. He yawned, prepared to be subjected to more sedative, though he was pleasantly surprised to hear shifting without a jab of a needle hitting his skin. He eyed Donatello. “I guess you earned your freedom.” He murmured. As he turned, shell shield facing Yuji, Yuji took the liberty to inspect it.
He eyed the structure. It was evidently braced for insane impact. If he’d worn that earlier, the knives would have most definitely broken immediately after striking it.

Being captured wasn’t something Yuji had expected, but nonetheless, he obeyed orders as he pleased. He was overjoyed to see Donatello offer him freedom for his quickly timed save. Ears twitching, Yuji found himself growing slightly more relaxed, even without sedatives.
No one in the gang was treated this way. If one failed, they’d be thrown from a roof in front of their peers as a demonstration of obedience. Mostly rejects turned to the gang and, of course, they got manipulated and blackmailed into staying. Everyone is for themself in that gang.

Seeing kindness left Yuji halfway melting. He appreciated something that Donatello barely thought twice about. His eyes shut, resting along the floor, humming patiently as he had been since his initial capture. The humming occupied his spare time where he was conscious.

Donatello joined at his side. He sank to the floor, legs crossed, eyes fixed on Yuji, specifically his ears and tail. “You’re a mutant, too.” He murmured to himself.
Yuji nodded, “I have a few thoughts about it.” He added.
“Shocking.” Donatello shot back, deadpan before smirking slightly as his comeback landed perfectly.
Yuji’s ear twitched, though he faintly smiled, snickering in utter defeat. “Fair enough,” he stretched out for the first time in hours. His bones released unhappy crunches. “I figured I was bitten by a rogue lab rat, probably mixed the DNA and whatever solution with my blood. Then something like DNA splicing could have covered the rest.”

A shake of his head immediately shut Yuji up, with Donatello’s disagreement painted all over his face. “Unlikely. You’d be more likely to have actually gotten injected with something that you so happened to forget about.”
Leaning into his palms like a lovesick fool, Yuji eyed Donatello, interest in the way he spoke. “You’re a smart one.” He smiled as he spoke.
Yuji halfway expected to be smacked with a harsh comeback, however, he was met with pleasant silence. A soft smile lifted Donatello’s features. He didn’t dare escape his shield, but this was a start. Yuji’s ears drooped in utter awe. He couldn’t stop staring. Certainly Cupid had struck him.

Two mutants eyeing one another with evident interest escalated into Donatello hurrying to help Yuji sit upright. “Maybe I used too much?” He groaned as Yuji nearly flopped over yet again.
Yuji laughed. He steadied himself as best as he could, afterwards flicking his tail along Donatello’s shell shield. “Can I feel this? It’s made so beautifully. Truly a durable piece.” The praise was getting to Donatello’s head fast.
He nodded, “Only this isn’t even my best work.” He laughed with a massive smirk on his face. Yuji was impressed.

Tail withdrawing, Yuji smiled at Donatello’s enthusiasm. “Really? Do you work with machinery or battle equipment?”
“I’m an inventor, period.” As if that wasn’t exciting enough, Yuji got to behold the sight of a mechanical staff, at least six feet tall. Yuji gaped at it as it was proudly flaunted.
Yuji’s tail swished almost like a dog’s would. “What a beauty! Look at that sleek surface and those chrome details.” His slight knowledge aided him in capturing Donatello’s interest and trust. Needless to say, it didn’t take much time for them to sit down together, chatter flying to and fro.

The two had lots to say back and forth to each other. They could barely contain themselves at that point. The more they spoke, the more they realized they’re almost the same— though Yuji found there was a massive skill gap between them. He was almost embarrassed before he saw the way Donatello flapped his hands, excitement strung all over his face. A new and unlikely friendship was thus formed. Yuji’s devotion had completely attached itself to Donatello like a lost duckling.

He was still a hostage, no mistaking that, but he found himself getting drugged less and being more friendly with his captor in only a single moment. He was shocked at how well they got along. Conversation just flew with Donatello. Questions flew from Yuji’s lips and Donatello never met one he couldn’t answer, always astounding Yuji, no matter the absurdity of it all.

Either way, he’d have to be restrained once again. That was alright by him. He didn’t expect to be all up against his new companion already. Perhaps someday he’d get close enough to feel his shell again. That, to Yuji, was truly a magical experience.