I should have mentioned, oops. Timeline wise, this fic can easily slot in between Wormquake and The Lonely Mutation of Baxter Stockman, in season 2.

tmnt = viacom

The Other Side of the Wrong Door
Part one: Day one.

Three days ago, Donnie was sitting watching a world go by, and everybody else was waiting for Donnie. Somewhere past the portal that led to the Land Of The Jellyfish, and the portal that showed a giant Kraang worm merrily terrorising the population of another New York, Raph sighed. Then again, louder. Then, louder still, he said, "So, remind me again why we're here?"

Donnie set down his clipboard, but didn't look up from the portal. "Because, Raph, there must be hundreds of different dimensions here. Think of everything we could learn from them!"

"Yeah, I get that – that's why you're here. Why are we here?" he asked, waving a hand in a sweeping gesture from himself to where Leo and Mikey were dorking around four portals down. This was so boring. Why couldn't Donnie do all the weird science by himself? Leave Raph to the good stuff – the important stuff – beating Kraang faces in until their creepy little tentacles waved a white flag made out of their tears.

Donnie raised his head, counted to three under his breath and on his right hand, and on cue Mikey's voice rang out: "WHOA, this entire planet is made out of pizza. Can we go?"

Leo, sounding tired, said, "No, Mikey" and there was the sound of a hand being gently slapped away.

"That's why," Donnie said. "Because Mikey and a big shiny new toy. Also, every single dimension here is only accessible through Kraang portals, including Dimension X, and I don't know about you, but if the Kraang catch us, I quite like my shell being attached to the rest of my body."

"So, we're here to be your bodyguards."

"Yup. Consider it your contribution to science."

Raph swallowed down the comment about how the only contribution science wanted from him or his brothers was a nice, slow dissection (or that other word that was just the same, except done while they were awake), and settled for rolling his eyes, instead.

"C'mon, Raph," Donnie added, scooting on the edge of his shell to the next portal. Raph hadn't seen Donnie this excited since the last time he'd stolen a centrifuge (he had, like, ten now). "You can't say you're not the littlest bit interested in different universes? I mean, did you read my notes on the one we let the worm into?"

"Nope."

"There were other turtles there! Us! So if there are more dimensions where other versions of us exist–"

"That means there are multiple Mikeys."

"–and millions of you, but my point is, what's the point?"

"Free-for-all?" Leo quipped, steering Mikey away from the universe run by a giant cat overlord. "Last Raph standing?"

Donnie made a show of rolling his eyes, his head lolling to the right. Raph, though, felt the grin creep across his face, and only part of it was to spite Donnie. "Yeah, I'd take that challenge." He flexed his arms for good measure.

"There's a universe where we turn into dragons and sparkle during battle," Donnie said flatly. "But go right ahead."

"Speaking of," Leo said. "You were saying?"

Donnie gestured idly to Metalhead's head, and his laptop, both sticking out of his satchel. "Well, I used what I could salvage from Metalhead's memory to get the algorithms the Kraang use to operate the portals so we can find out what it is they're after – technically, there are infinite possibilities, but there's obviously not infinite portals here, so–"

"Science, we get it," Raph interrupted.

Donnie glared. "And," he bit out, "there are patterns. Wherever there's Kraang, there's some variation of us — at least, as far as I can tell. Wherever there's an us, there's an April. But for some reason, the Kraang don't seem to be interested in those other Aprils, just our April."

"I'm not following."

"My point is, meathead, that there are literally millions and millions of Aprils out there. The Kraang could just walk through a portal and pick one up like they're at the mall, if they wanted, but they only seem to want ours. So by studying the other universes they've got lined up here, maybe we can find out what's so special about her." Donnie's mouth pulled into a thoughtful frown. "A lot of these worlds are really different though – not just the jellyfish, but there's a universe where Leo's running around in a trenchcoat and terrible sunglasses and the Foot are in control, and one where we're all still babies and I think April's adopted us, and then," he said, snotty and smug, "there's the universe where Raph is an anti-intellectual troglodyte – oh, wait, that's ours."

Raph aimed a kick at the bottom of Donnie's shell. "Very funny."

Donnie took the kick with a smirk and scooted along to another portal. Leo shrugged, failing at hiding his own smile. "He has a point, Raph," he said placatingly, and patted Raph's shoulder as he passed by to go look at some other weird place. "The more we know about the portals, the better a shot we've got against the Kraang."

Raph rolled his eyes and looked over Donnie's head into the new universe: a tropical beach and, following Donnie's gaze, a pretty coppery mermaid. When Raph looked closer, his brother was staring, his jaw slack, and aw jeez, okay, no. Raph was not going to sit and watch Donnie moon over every April in the multiverse. He got to his feet. Maybe he could convince Leo to take over, and he could haul Mikey back home.

Maybe he could find a universe that was actually interesting to watch.

They hadn't found a universe where he was fighting dinosaurs in a giant arena, yet, or one where Mikey was running around New York as a superhero.

"Fine," he said, swiping at the clipboard Donnie somehow produced from the middle of nowhere and tucking it under his arm. "I'll go check up here."

He didn't wait for Donnie to reply – Donnie was too busy humming Kiss the Girl, probably – before glancing through portals, his eyes narrowing when he saw a turtle in a trenchcoat facing off against a dork in a mask and filed that knowledge away - that in some universes, Casey Jones had discovered what working out meant.

The next portal, thirty seconds later and across the corridor, looked like regular old New York. A little flashier, maybe? But ultimately, just New York. A blur of green caught his eye and – sure, okay. Why not.

He sat and watched, ticking off boxes on Donnie's stupid clipboard – yes, there were other turtles, no, he hadn't seen another April, yes, there were Kraang–

There were Kraang, surrounding a lone turtle, in the middle of an alley.

There were Kraang, surrounding a lone turtle, in an orange bandana, in the middle of an alley. And Mikey was losing. Two against one, and these Kraang were bigger, more solid-looking, than the ones Raph was used to watching Mikey take apart with a chain and some spit.

Donnie – and Leo – had said it very clearly, several times: do not go through the portal, definitely don't do it alone, and definitely, definitely, do not get involved with whatever it may be that inspires you to go cannonballing into an ALTERNATE UNIVERSE.

But seriously, how bad could it be? It wasn't like either of them would just leave a Mikey to fend for himself. He looked at the portal, then back to his brothers. One way in, one way out – that was how Donnie had said it worked. He could jump in, even the odds a little, maybe pound a face in or three, and then jump back out. Nice and easy. No harm done, right?

Bonus: Donnie would freak.

Double bonus: Leo would freak.

And the icing on the cake would be that Raph could be doing something with his time that wasn't babysitting.

So he jumped.

Passing through felt like he'd spilled soda on himself, fizzing at his skin and under his shell, and he dropped neatly to a fire escape above the alley. From here he could see the fight more clearly: Mikey grim-faced and coping, but it was just that – coping; waiting for back-up. Mikey wasn't a terrible ninja, Raph knew that better than anybody, but he also knew that Mikey knew how to win a fight, and how to deal with one he couldn't get away from. He dodged instead of taking the hit, weaved between his enemies to keep them off-balance, favoured the kusarigama instead of getting up close with his 'chuks.

Well, Raph thought. Back-up was right here. He cricked his neck to either side, already craving the fight. This was what Raph was good at, not sitting around with a clipboard; protecting Mikey was about caving in the face of whatever was after him, not holding his hand to make sure he didn't get lost.

"Hey, Starscream!" he yelled. The left robot turned. There was a little glass casing in the chest cavity, with a Kraang pilot inside, and Raph threw himself off of the fire-escape, hurling all of his weight feet-first at the glass at the same time that Mikey yanked the chain that had wrapped around a metal leg. The impact slammed through Raph's feet, shaking him in his shell, and as the machine staggered off-balance, Raph flipped neatly to the ground, pulling his shoulders in and throwing himself again.

Raph was a battering ram, a wrecking ball. He came in and got the job done.

On the opposite fire-escape, two more shadows materialised, shades in the dark before they slalomed into the light, weapons drawn and blurring. Raph saw the whites of their eyes in the corner of his own a second before they both slammed into the second robot.

Now the odds were a little better. "That wasn't so hard," Raph said, turning to look at this universe's version of his brothers. So much for in and out. "Sorry to just bust in here, but you looked like you could use a–" –hand, was what he meant to say, but his jaw slammed shut when someone started screaming. It took him a moment to understand who was screaming – Mikey, backing up with one finger pointing directly at Raph.

Of all the things Raph had expected (like, hey thanks or nice work), his brother screaming in his face was not on the list. "Mikey–" he started, taking a step forward, but Mikey backed off, still pointing, and still screaming. "Okay, seriously, knock it off!"

"Oh my god." Still staring at Raph, Donnie reached down and gently covered Mikey's mouth. "Raph– ow!" He yanked his hand back, and Mikey spat to the side, looking briefly aggrieved before resuming his pointing.

"That's not Raph. That can't be Raph! Look at him, Donnie!"

"I am! But–"

"Donnie," There was gravel in Leo's voice that shouldn't have been there; Raph's gut tensed at the sound of it. "What are the chances that–"

"Infinitesimal. But there's still a chance. Same as we always do." Donnie pressed his mouth into a thin line, his brow bunching behind his mask. "Raph–"

To their rear, one of the robots staggered to its feet.

Leo drew his swords again. "We can talk about this later – get into position! We take them down, we go home."

"And Donnie gets two shiny new toys," Mikey put in, though the humour was flat.

This time, Raph thought, the fight should have been easier. He knew his brothers, he knew how they fought: Mikey and Donnie running distraction while he brought power and Leo brought finesse. When Leo struck, he struck true; when Donnie ran defence, nothing got past him. Mikey was a blur of laughter and skill.

Except it was all wrong.

Where Leo should have had Raph's back, Leo had Donnie's. Where Donnie and Mikey should be together, Mikey was with Leo. They fought in a triangle, closed-ranks and silent, and there was no room for him.

Fighting alone wasn't the thing that scared Raph. He could handle himself. But it was either that, or in a group – not some kind of an in-between.

He didn't fit, here.

By the time Raph felt the fight in his shoulders, he recognised it again, same as with Mikey – they weren't fighting to win. Their blades were glancing off of joints, barely scratching metalwork. They were holding out for back-up.

"Leo, where the hell are they!?" Donnie yelled. Leo didn't answer.

"Where are wh– whoa," Raph started, ducking the crack of a pink whip. "Who are we waiting for?"

"Friends," Leo bit out grudgingly. "Shut up and focus!"

Back home, Raph would have told Leo exactly what he could focus on (my foot, in your shell), but this wasn't his Leo.

"HEY GUYS," someone yelled from a rooftop – a voice Raph knew, but couldn't place. "THE CAVALRY'S HERE. WE BROUGHT TOYS."

"Yes!" Mikey yelled. "Fireworks time!"

"Donnie and Mikey, go with him," Leo barked out, as two more shapes dropped into the alley. "Raph, you're with me. Angel, wait for your shot!"

"Wait, what?" the woman said, a second before she threw herself out of the way of Mikey as he went pinballing past. "Raph!?"

"Why is this so surprising!?" Raph yelled, as Leo hauled him to robot number 2. It was even uglier now they'd beaten it down a little. The protective glass casing had shattered, leaving the Kraang inside to pig-squeal at them, and the left arm stuttered from the impact with the wall. "Why is this such a big deal!? What am I, dead here or something?" He looked to Leo as he said it, throwing an arm out to the side, and he stared when his brother – this version of his brother – bit down on his lip and resolutely did not answer. "Leo…?"

"On my mark," Leo said instead, nodding forward. "We get it into position for Angel."

"Who the hell is Angel!?"

"Just shut up and do as I say!"

"Well hey, if I didn't already know you were Leo, there's the proof!" Raph snarled, but did what Leo said.

"Now!"

Leo went high and Raph went low, throwing his weight into the legs of the robot with his shoulder. It staggered, then caught Raph as he rebounded, slamming its foot into his gut. Leo yelled Raph's name as he landed shell-first on the tarmac and changed direction, neatly sliding to guard as the robot – dimly, Raph realised that Mikey hadn't tried to name this one yet – lashed out with the whip again.

Raph watched, winded and helpless, as the thick pink band of light reared back and slapped the portal device out of the air. As the little contraption fell, Raph watched the shimmer of the portal closing, a flash of his Mikey's panicked face there before the sky filled in the gap.

"Angel!" Leo ordered, and the whip was now wrapped around his swords. "Take it down."

Raph heard the sound of the shotgun before he saw it, pump-action like the ones on TV. Then he heard a sound like thunder, like roaring, like a bomb going off, and he hit the deck again out of sheer self-preservation. Guns – real guns – hadn't come anywhere near their part of New York, at least not in the fights Raph had been in.

The robot closest to Leo dropped to one knee, smoke hissing from the joint. The woman shot again, and took out the other knee. It hit the ground, head bowed. Leo cut its neck. Power drained out of it, and it made a soft, droning sigh as the lights went out.

To Raph's left, the other robot – the one Mikey and Donnie and the other human was taking care of – didn't seem to care about its fallen comrade, and kept coming.

Angel reloaded, and shot the Kraang in the face.

Groaning, Raph reached up, peeling a wet tentacle off of his head and flicking it aside. He forced down the sourness in his throat and turned, surveying the alley as he got back to his feet. The woman – Angel – was reloading her shotgun as Mikey pulled Leo up to standing.

Okay, he told himself, taking the moment to catch his breath and count the things he'd just seen. Big Kraang droids, still piloted by a nice squishy weak spot – that here, they weren't afraid to target with things other than fists. Two humans, clad in black. And then, his brothers.

They all looked like they'd spent a year or two going through the wringer; even in the dark, Raph could make out the thick gouges in the scutes on Leo's plastron. Something dark caught at his gut – not-quite-half worry, not-quite-half fear, because Leo was good, he'd always been good, and yet something had almost taken a chunk out of him.

He counted again. Two humans, three turtles. Purple, blue, orange.

What am I, dead here?

Not-quite-half panic.

He forced it away, taking a deep breath and plastering on his default cocky smile. "…so, this is awkward," he said, palming the portal device and tossing it once, before holding it out to his brothers. "Uhhh, Donnie. You think you can turn this back on?"

The tall, human guy at Leo's left reeled back, gloved hand covering his mouth in revulsion. Raph caught the flash of black space instead of white teeth – Casey?! – before the man spoke.

"Holy fuck," Casey said, half-way between anger and grief. "They're making Raphs now, too?"

tbc.