Chapter Text
Day 1- 11:00pm
Metal rungs clinked softly under their weight as they descended the fire escape. At the bottom, they dropped the last few feet into the alley, landing in near silence as the scent of grease and baked dough drifted from the pizza place beside them.
April slipped inside, the bell over the door jingling as she opened the door, while the others kept to the shadows within the alleyway, staying out of human eyes.
She returned a few minutes later with a stack of boxes balanced in her arms. With that handled, Leo pried open a nearby manhole, and one by one they disappeared beneath the street, the cover settling back into place above them.
The tunnels swallowed them in its dim lighting and echoing drips. Leon and Donnie followed closely, memorizing the route as their alternates led the way.
When they finally reached the lair, Don was in his lab within seconds, rushing over to grab his laptop and bringing it to the desk.
Behind him, the others filtered in, the heavy lab door sliding shut with a metallic clang. The smell of pizza immediately wafted through the room as they set the boxes down on the nearest workbench; they were opened quickly, and multiple hands fought to reach in and snag a piece, as six hungry turtles and one human dug in.
Donnie grabbed a slice after looking at the flavour options, took a quick bite, then tapped at his wrist; a hologram burst to life from his vambrace, casting a gentle purple glow over his arm.
Don’s attention snapped away from his laptop instantly. He stepped closer, eyes wide as he took in the projection. “Is that… a portable hard light interface?” He asked with barely contained excitement. He leaned in, scanning the device, his gaze flicking over Donnie’s arm as his hand waved between the screen and his limb. “I don’t see anything on your wrist that should make that possible!”
Donnie grinned. “It’s a bracelet I designed to fit under our wraps.” He explained, tapping the edge of the projection as it shifted and expanded. “Basically a wearable computer, it controls all my tech, syncs with my lab, and is our communicators; everything I need is right at my fingertips.”
“Oh, man...” Raph groaned from across the bench, folding his arms as he leaned back. “Here comes the nerd fest.”
“What I really want to know—” Don cut in, ignoring Raph as he stepped closer. “Is what kind of tech do you use for those weapons? How were they able to make a shield, guns and portals earlier? I’ve never seen anything like that.”
Donnie’s grin sharpened with a spark of mischief. “That’s because it isn’t tech—”
“—It’s mystics, baybee!” Leon finished for Donnie, flashing a proud, smug grin.
“Thank you, Leon. I never would've been able to finish that sentence on my own, he said, full of sarcasm.” Donnie said dryly, rolling his eyes. “But yes, my weapons and Leon’s portals are mystics.”
“Mystics?” Leo echoed, brows knitting slightly as he tried to process it.
In response, Donnie lifted his hand. The purple markings along his face, shoulders, wrists and thighs flared to life as a bo staff formed in his grip. Leon mirrored him a second later, drawing one of his swords from his back, with his own markings glowing, while runes lit up the sword.
“It’s our ninpo.” Leon smiled. “An ancient Hamato power that’s tied to our connection with our family.”
Mikey’s eyes were practically sparkling. “So… you guys have actual magic?” He pointed between Donnie and Leon, bouncing slightly on the balls of his feet.
“Excuse me, have you forgotten that April has actual magic?” Don huffed as he defended her.
“Yeah, but these guys have glowing weapons and skin!” Mikey shot back, gesturing towards the two before poking Donnie’s bo.
Donnie let out a soft chuckle, Leon’s grin widening in response, and with a shared glance, they both let their mystics fade; the bo in Donnie’s hand dissolved into pixels while Leon put his sword back into its sheath.
“I do have a question,” Donnie said, lowering his hand as the last traces of purple light faded from his skin. “I haven’t seen any sort of mystic energy here, which makes me think you don’t have a hidden mystic city. So… where did your Baron Draxum make you? And where is he now? He could be a huge help in figuring out how to get us home.”
“Who the hell is Baron Draxum?” Raph cut in, brows knitting together as he looked between them.
“…It’s complicated,” Leon admitted with a grimace. “Mikey thinks he’s family because he created us, but he also threw me off a roof once and used to be evil.”
“Created?” Leo echoed with confusion as he tilted his head. “Like… in a lab?”
“Yeah? Weren't you?” Leon asked.
“We were… accidentally mutated,” Don explained. “Sensei bought us from a pet store, and while he was walking home, there was an incident where we were all exposed to mutagen.”
Donnie’s brows lifted, interest sharpening. “Huh. That’s definitely something that differs between our universes.”
“Hold on—” Leo cut in, raising a hand and pointing between them, trying to piece it together. “I feel like we’re just skipping past the whole created part.” His gaze locked onto Leon and Donnie. “What do you mean created? Like… made on purpose? For something specific?”
“Oh yeah!” Donnie said, far too casually, like he was explaining a new gadget instead of his own origin. “We were created and genetically engineered for war.” He shrugged. “Draxum kidnapped our pops and spliced his DNA with four baby turtles.” He waved a hand. “His end goal was to wipe out humanity and return the Earth to the yokai after hearing a prophecy about the destruction of his people.”
Don’s expression turned to shock as the words sank in. “Wait... You’re saying you were made to— what? Take out humans?”
Leon winced, then quickly stepped in, lifting both hands in a gesture of peace. “Okay, so, what my twin is trying to say is that we were originally made for war. But instead, we were raised to be heroes for everyone on our Earth, which means most of the yokai and humans.”
Raph's jaw dropped. "Wait a second, now I'm confused. How are you twins if you're the oldest and you’re the second youngest?" He pointed at Leon and then Donnie
"I'm not..." Leon furrowed his brows. "Raph's the oldest in our family. Donnie and I are the middle children; we’re twins because Draxum decided to mix our DNA. He figured our species would complement each other once we got past the whole cannibalism phase; we share a birthday and everything, I'm three minutes older than him."
Donnie crossed his arms, eye twitching. "Do you have to bring that up every time?"
"It’s an important piece of our lore." Leon grinned, giving Donnie's shoulder a pat. “You know, for your research or data collection or whatever you like to call it, and—”
"What is going on in here? And... who are these two?" Every head snapped toward the doorway where Master Splinter stood in the entrance, his eyes narrowed in suspicion as he looked at the two extra turtles.
Leon leaned toward Donnie with a chuckle to whisper. "That must be their Splinter. He's... a lot taller than ours."
Donnie pressed a hand over his mouth to suppress a laugh. Splinter glared at them; Donnie then coughed and looked at the floor.
"Sensei!" Leo blurted, moving to be in front of everyone else. "It’s ok, I can explain; this is, uh, Leonardo and Donatello. From a different dimension."
Splinter’s tail flicked behind him. "A different dimension?"
Donnie inhaled deeply and stepped forward with a flourish. "To be exact, our universe exists as one story within a vast, high-dimensional multiverse; we’re an interconnected web of parallel realities, each governed by its own laws and historical developments. Due to an unnatural portal event, we were unintentionally displaced from our original universe and translocated directly into this dim—."
"Donatello." Splinter cut Donnie off with an annoyed sigh. "My Donatello. Explain. Simply."
Don stiffened. A flicker of nerves crossed his face as he rubbed the back of his neck. "Right. Uh... simply. They’re the same characters as Leo and I, with a different story. And somehow, they ended up here without any information on how they got here or how to get home.”
“They don’t have anywhere else to stay right now. Would they be allowed to stay with us in the lair until they figure out how to return to their dimension?” Leo asked.
Splinter sighed. "As long as they pose no threat to us, they may stay here. But understand this.” His gaze sharpened as it fell on Leon and Donnie. “While you are under my roof, you will obey the rules set in place."
"Hai, Sensei!" The four turtles and April of this dimension responded instantly, voices snapping into unison.
Leon and Donnie exchanged a glance before Donnie raised a thumbs-up; Leon mirrored it a beat later. "Absolutely, thank you," he said, far too quickly.
Splinter's brow arched, unimpressed. "It is late. You will all be awake and prepared for training at dawn. That includes our two guests. Leonardo, can you set up the guest room for one more and show them where it is?" He stared at Leon and Donnie. "Please do not wander around the lair through the night or disturb the others, and you will be ready and in the dojo in the morning."
Leo bowed his head. "Of course, Sensei."
Splinter turned and padded down the hall, the soft tap of his claws on the concrete fading with him.
Donnie cocked his head, curiosity sharpening as soon as Splinter was gone. "Wait... why do you all call him Sensei? Isn't he... your dad?"
"He is our father." Leo's gaze followed the empty hallway where Splinter had disappeared. "But he raised us to be ninja first. He’s been preparing us, so we can survive, and so we can protect each other for future battles."
Donnie and Leon exchanged a look.
"Alright, we all heard Splinter, we’ve all had a long day, and I think it’s time for some rest," Leo said firmly. He then glared at both purple-clad turtles. "You two as well. I am not allowing either Donatello from either dimension to stay up late."
"I agree," Leon added immediately, stepping closer to his Donnie. "And I'm not going to sleep until you're asleep." He poked Donnie's cheek for emphasis while wearing a grin. Donnie snapped his teeth at the offending digit, and Leon pulled away quickly with a yelp. The others looking horrified at the display.
Don opened his mouth to protest going to bed.
"No experiments." Leo pointed at him.
"No scans." Leon cut in without missing a beat.
"No research, tests, or projects," Leo added, glaring sharply between the two geniuses, clearly well acquainted with this exact routine.
"And do not say this will only take five minutes." Leon finished, already steering them toward the hallway. "Because five minutes turns into sunrise and then we all have to deal with two tired Donnies for the next day, and I already have a hard time dealing with one most days."
Both Donnies groaned in perfect sync, shoulders slumping.
"You're both actively crushing scientific progress." Donnie crossed his arms, planting his feet and causing Leon to stumble at the sudden stop.
"Yeah!" Don agreed. "Do you even realize how historic this moment is?"
"History can wait until morning." Leo gestured toward the lab door. "Beds. Sleep. Brains offline."
"And then—" Leon added cheerfully. "—After some rest, you both can science your hearts out."
The Donnies trudged along, defeated.
Reluctantly, everyone filed out of the lab. Raph, Mikey, and Don peeled off toward their own rooms, voices already fading into the distance, while April stayed with Leo, Leon, and Donnie as they headed down a quieter corridor.
They stopped at the spare bedrooms. Leo opened the door and led them in; a neatly made bed was against one wall, an extra blanket folded with care on the end. Leo walked in and knelt down to reach under the bed for a camping mattress already inflated; he placed it on the other side of the room, then grabbed the spare blanket before smoothing it flat with his hand.
"April's staying the night." He rubbed the back of his neck sheepishly. "I hope you don't mind sharing a room; we only have the two spares. Casey usually crashes in here."
"We're good with that; we really do appreciate you guys letting us stay here." Leon smiled as Donnie nodded in agreement, fatigue from the long day finally settling into his bones.
Leo headed back out of the room. "Alright. Well, make yourselves at home. One of us'll come grab you in the morning for training."
Leon gave a short nod while Donnie lifted a hand in a tired half-wave. They exchanged goodnights; April offered a small smile before slipping into the room next to them. Leon pushed the door to their room closed; he and Donnie both ignored the rolled mat on the floor. Donnie moved automatically toward the bed, already turning to lie down.
"Nuh uh." Leon crossed his arms. "I don't care if we're in a different dimension. You are not sleeping in your battleshell."
Donnie's shoulders tensed. "Lee..."
"We both came to an agreement that you wouldn't sleep in your battleshell anymore." Leon glared. "You know you’re risking damaging your back even more."
Donnie began scratching at his arm before he even realized he was doing it. Since the invasion, taking off the armour had gotten harder; the weight of the metal was proof his back was protected, that nothing could claw past his defences or wriggle its way into his leathery carapace again.
Without it meant being vulnerable.
Leon grabbed his hand to stop him from the self-destructive habit while pulling him out of his head.
“Do you really think I would ever allow anything to happen to you?” Leon stepped behind him and grabbed the sides of the shell. “I’ve got your back.”
“I know you do.” Donnie chuckled nervously. “But we’re in a completely new dimension; we don’t know what to expect here yet. We already know that... they’re here, what if they...?” Donnie shuddered.
Leon gave him a flat look. “Do you need me to remind you in 95k words why it’s a bad idea to keep your battleshell on the whole time you’re in another dimension?”
Donnie sighed. “No...” His hands trembled as he pressed the release; the armour disengaged with a quiet hiss. Leon took the weight of it and set it down against the wall.
"There," Leon slung an arm around his shoulder, a teasing warmth in his voice. "See? Nothing is going to happen, not while Ol’ Neon Leon is here."
Donnie smiled, but Leon could see the rising panic on his face and nudged him toward the bed. "C'mon. Get in. Im exhausted."
Donnie shuffled to be closest to the wall and lay on his stomach, muscles tense for only a heartbeat before Leon followed, curling in close.
When they were tots and shared a bed, Leon constantly used Donnie's shell as a pillow. Even as they got older and moved into separate rooms, they continued the tradition. Whenever they couldn't sleep, Leon would finally fall asleep to the steady rise and fall of Donnie's breathing while Donnie used Leon's weight across his back, something that felt protective, the only thing that ever truly let them both relax enough to sleep. It had been that way since the night they were mutated.
Leon rested his head against Donnie's shell, an arm draped lightly across Donnie's back, shifting just enough to get comfortable, already half asleep. "You're safe." He murmured. "I've got you."
"Don't forget, I've got your back too," Donnie whispered in return as he closed his eyes.