The resident hothead knew when the hockey-masked teen had arrived when cries of "Gap-tooth!" and "Cave-mouth!" reached the kitchen and he'd exchanged a look with Mikey before abandoning his half-eaten ramen noodles to see what the fuss was about. As normal as the arguments between the two rivals for April's affections were, he wasn't about to stand by and let Casey pick fights with his younger brother if this was anything actually serious.

He could guess what had crawled up Donnie's shell. Casey had told him about his intent to take April on a hunt for her currently mutated bat-dad and Raph had to struggle not to bang his head against the wall when his human friend voiced that he wanted to see if he could make it into a date. Obviously, Raph told him off for being a self-contorted idiot and Casey decided to stick with the original meet-up plans.

Or so he said.

If the noise from within the lab was any indication, Casey probably went to Donnie to imply something of the sort to make him jealous and his gullible brother fell for the ruse like a true dork. This musing almost made Raph want to simply leave them to their competitive idiocy, but his protective side won out halfway through his abandonment and he grabbed a comic from his room instead.

He'd then dragged himself into the lab and moved around the two arguing teens to take a seat at Donnie's desk, getting comfortable in the swivel chair as the creative insults continued.

"Smarty-shell!"

"Kraang-brain!"

"Lumber-wielder!"

"Stick-whacker!"

At some point Mikey came in with a bowl of popcorn and hopped onto the desk near Raph, watching the several minute long insult-driven argument that didn't show any signs of stopping. Leaning sideways and gaining a disapproving glare from the hothead, Mikey seemed oblivious to his annoyance. "Who's winning?"

"It isn't a contest, knucklehead."

"Yeah... But who's winning?"

Raph shoved his youngest brother's head out of his personal bubble and flipped the page in his comic to make it apparent that he was too busy to answer stupid questions. Mikey shrugged him off and waved Leo over, the leader having realized that everyone else in the lair seemed to be hanging in the lab and followed suit.

Donnie and Casey seemed mostly oblivious to their presence so the leader obliged Mikey and made his way over. "Who's winning?"

Raph facepalmed as Mikey shrugged, "Think it's Donnie. Casey paused for a good few seconds earlier when he couldn't think of one. Came up with "techno-geek" at the last moment though."

Leo gave a short "hmmm" of thought as he swiped some of Mikey's popcorn when the youngest glanced back over to the infuriated teens, who had degraded into one-worded insults.

"Doofus!"

"Dork!"

"Moron!"

"Egghead!"

"Idiot!"

"Mutant!"

In that instant, the entire lab seemed to freeze into a shocked silence.

The general aspect of being called a mutant wasn't surprising in the slightest. The brothers had long recognized and accepted what they were. If this was said in any other kind of instance, none of them would have given this a second thought.

But in Casey's few seconds to grapple for an insult; he'd chosen very, very poorly. And it wasn't until after the crude word had left his mouth and practically slammed into the self-conscious mind of one of his friends that he realized how much he'd screwed messed up.

There wasn't the slightest bit of pride that came from watching his wide-eyed rival take a step back from him, looking as though he'd suddenly pulled out a gun and threatened to fire it. The shock in the autumn gaze was overrun by hurt and for a second, Casey just stood there, unsure what to do in the deafening silence.

And then he was abruptly body slammed into the ground.

He managed to catch himself before he could faceplant and scrambled back to his feet, spinning around and completely prepared to face the furious emerald gaze of Raphael. This is why he was totally taken off guard to meet the narrowed gaze of an enraged Leonardo, who looked totally prepared to shove him back to the ground.

What!? Is!? Wrong with you!?" The fury in the normally passive leader's tone was so close to Raph's that it suddenly dawned on Casey that, despite the hothead's constant insistence of the opposite, there may have been a chance the two were related after all.

At the thought of his unspoken best friend, he hesitantly glanced in his direction and saw that Raph had gotten to his feet but hadn't moved after that; his comic held in a death grip in one hand as he stared at Casey with a wide-eyed look of haunted betrayal.

"I-I didn't mean it- like-like that!" Casey sputtered as he glanced back to the fist-clenching leader, still trying to comprehend just how much he looked like Raph.

"Seemed pretty self-explanatory to me." Leo growled as he raised a fist, and for a second, Casey thought he would need to defend himself before the leader tried socking him in the face.

Instead, Raph suddenly appeared beside the leader and grabbed Leo's wrist, forcing him to lower his arm as he snapped, "Don't do anything you'll regret, fearless."

"That's hilarious coming from you." Leo hissed through gritted teeth, his momma bear side apparently coming out rough and strong.

Raph narrowed his eyes and moved between the two of them, pointing a finger over at the stunned genius. Mikey was by his side and trying to make a distracting conversation, but Donnie's deer-in-the-headlights stare was locked on the three of them as though his mind was no longer processing reality and autopilot had left him completely lost. "I'll deal with Casey; you go to Donnie."

"Don't tell me what to-!"

"Look at him!" Raph interrupted curtly before lowering his voice. "He needs you, Leo."

Leo's hot anger rushed out in a wave as Raph spoke and then he seemed to hesitate, apprehensive sapphire gaze shifting in the genius's direction. It was clear by the way his glare softened that he'd already made his decision, but Leo still shot the human teen one last dirty look of contemplation before abruptly turning and heading in Donnie's direction.

"Dang, Raph, Leo was really-"

Raph slammed him in the gut and sent him toppling to the ground, the force of the blow less effective than the fact that he was surprised to have received it. Somehow, he was convinced that it would have hurt a lot more if it had come from Leo. The dead-set glare and fighting stature were making Raph look like Raph again, so Casey was at least glad their weird personality trade was over.

"You Kraang-headed, numbskull of a thoughtless jerk!" Raph spat as Casey rubbed his chest and stood with a slight wince, deciding that if both older brothers were making such a big deal about it, he must have seriously messed up. "Of all the things you could- why would you ever- and to Donnie of all- I can't believe you just- What is wrong with you?!"

The fact that Raph seemed to have lost the ability to speak and yet got his point across perfectly was one of the reasons why Casey easily accepted him as his unspoken best friend. He never had to wonder whether he was reading the guy right or not. Raph usually just let him know with a fist to the jaw or a sputtered line of insults. He wished every relationship was that easy.

"I'm sure Don over there could give you a good list." Casey joked, only to receive an irritated scowl in response. Realizing that this was not the time for charming humor, the hockey teen relented, "Alright, alright, I messed up. But, I mean, I wouldn't be all that annoyed if someone called me "human", so it can't be that big a deal, right?"

Raph looked like he wanted to sock him in the chest again and Casey prepared himself to block the blow, but the hothead seemed to change his mind last second and grabbed his arm to drag him a few feet away instead. Casey was barely able to get his footing with the force of the tug.

Ripping his arm back when they stopped, Casey rubbed it and shot him an indignant look, but Raph ignored it. Jabbing a finger into his forehead, Raph growled, "Maybe it doesn't seem like that big a deal to you, but it's a big thing for us. Most of all, Don. We don't exactly 'fit in' with the humans up there, hence the wild screaming every time we show up."

Raph sent a sharp look in the direction of the brothers and Casey followed his gaze, seeing that Mikey had finally succeeded in getting a conversation started and Leo had coaxed the suddenly shaky Donnie to sit the cot, both brothers dawning forced reassuring smiles as Donnie stared down at his lap, responding with barely spoken utters every now and then.

"If you tell any of them I said this, you're dead." Raph warned in a low tone. "So pretend you figured it out on your own because I will deny ever telling you every time..." The hothead's demeanor softened slightly. "But... Don has always taken this kinda thing hard. I mean, we all do, obviously, no one wants people freaking out every time you just walk into a room, but... I dunno, it messes with him more than us, I guess."

He let off a gruff sigh. "Leo says it's something about never being able to really make a difference or actually feel accepted or some other stupid nonsense- but the reason really doesn't matter!"

Fixing Casey with a hard stare, he grumbled, "We've told Don millions of times that there's nothing wrong with being a mutant. It's just what we are and there's nothing to be ashamed about. If anything, we're better than all'a you!" The hothead threw both hands in exasperation. "But now you've gone ahead and told him that being a mutant is- is- like an insult!"

Despite the jab at humankind, Casey felt a worm of guilt make its way into his chest and he took another awkward glance at the genius, suddenly wishing he'd just let him win the verbal contest. He couldn't understand why he hadn't seen that before; he'd been judged plenty of times in his life. He knew what unfair criticism could do to a person. Which was nothing good.

Man, he really was a jerk.

"Raph, I-"

Raph clamped a hand over his mouth when Casey turned to face him again. "No. Not to me. To him. And make sure you add how much of an idiot you are. We don't need the brainiac thinking any of your stupidity means anything."

Casey got the silent message to fix what he'd broken and spotted the worry that hid beneath the hothead's annoyed glare. Swatting his hand dismissively and scoffing, the brazen teen insisted, "If there's one thing Jones has mastered over years of messing up, it's how to smooth things over." He pointed his thumb at his chest. "I got this."

Raph rolled his eyes but seemed to accept this answer and he began to make his way over to Donnie, the human teen following his lead. Raph exchanged a look with Mikey and the youngest gave a concerned shrug in response; Leo's full attention on the murmured conversation he was having with the dejected genius.

Donnie went completely silent the moment that they approached and began looking everywhere but at them, the leader's hand clasped tightly around his wrist a clear sign of why he hadn't sprinted off the cot yet. Leo gave Casey a dark look and received one in return from Raph as Mikey sensed the tense rise in the atmosphere, instinctively scooting closer to Donnie.

"I don't want to talk." Donnie suddenly announced with the low and clipped voice of someone who was tired of repeating the same thing. He blatantly ignored the boys across from them as he turned a weak glare to Leo. "If it's alright with you, I really should be getting back to work."

Casey decided to throw in his two cents before the eldest brother could reply. "Well, you won't hear me complaining 'cause I have something to say and I don't wanna hear you blabbering."

"Casey-" Donnie grumbled irritably, clearly about to either demand he leave his lab or tell him to shut his pizza hole. Proud that he'd caught his attention in the only way he knew how and not about to allow him try and boss him around, Casey didn't bother to let him finish. "Yeah, yeah, yeah. I'm a puck head and sometimes- eh, maybe I don't think before I do. You're not wrong."

Donnie's head shot towards him so fast Casey wondered if he would break his neck with the force of the jolt. The genius squinted at him as though inspecting for proof that he was actually a clone and not the real deal. "You- what?"

Casey shrugged carelessly, trying to ignore the other turtles that he knew were probably gapping at him. "Nice try. You ain't going to get me to say it a second time. -But, I do wanna say... Well, I wasn't tryin' to get April hurt when we went searching for her dad and I wasn't tryin' to hurt you just now when I was blowin' off steam. Just kinda happened, you know?"

The widening eyes of understanding from the surrounding brothers told him that none of them paid enough attention to the conversation before the contest to realize what it had actually been about. He supposed that was a good thing; it meant that a household full of ninjas didn't spend their lives eavesdropping on one another.

Donnie stayed completely silent, clearly at a loss for words, so Casey continued before his brash confidence could fail him. "Anyway, I don't really think there's nothing wrong with being a mutant. It's freaking metal, man! Why do you think I hang here all the time? Heck, I wouldn't mind being a mutant!"

He reconsidered his words at the skeptical look he got in response, "Maybe not a turtle though. Something cooler- like a lion. Or a dragon!"

Donnie snorted as he crossed his arms indignantly, "Dragons aren't real, doofus."

"Aliens and mutants were real, weren't they?" Casey shot back. "Who says the same can't be said for wicked dragons?"

"Me." Donnie announced with a superior look but the hockey teen easily swatted this statement to the side. "Like I'd just take your word for it."

"You're an imbecile, Casey Jones." Donnie replied fondly as he got to his feet and stalked past him, a small grin visible as he purposely knocked his shoulder. Casey spun around in time to land a playful punch in return before he could move out of reach. "And you're an egghead, Donatello!"

Donnie waved a hand dismissively as he returned to his desk and took Raph's comic from the floor, setting it on the edge of his wooden workplace. Plopping down in his chair and promptly ignoring the rest of their existence, Donnie grabbed his goggles, slipped them on, and resumed the experimental construction of the retromutagen for Mr. O'Neil.

Leo let out a long sigh of relief as Mikey positively beamed and Raph gave Casey an appraising smirk. "Looks like you're not as stupid as you look."

Smoothing his hair back smugly, he boasted, "Told ya. Casey Jones knows what he's doing."

"Only cause you mess up so much." Raph reminded him slyly, the hockey teen releasing an annoyed huff. "At least I know how to make it up when I done wrong."

Raph narrowed his eyes accusingly. "What's that supposed to mean?"

"You totally broke my Swamp-Man figure and never even said sorry!" Mikey spoke up as he recalled the devious crime from the evening before, his heart going out in mourning to the action figure that had yet to be repaired.

"Why should I apologize when it wasn't my fault!?"

"Dude! You threw it at me!" Mikey jumped to his feet in order to toss out both hands to further express his grievances but Raph stood his ground. "Stop being so annoying and leaving your stupid toys lying around and then I won't have ta throw them!"

Mikey was clearly on the edge of repeating his full-fledged temper tantrum from the exact same argument they'd already gone through, but the genius's already aggravated voice spoke first.

"If you guys are really going to do this, then do it anywhere but here. Just make sure the lab doors get closed on the way out; I promise you I don't wanna hear any of it."

Raph shrugged and then began to make his way from the lab; the smug Casey followed him as he relished the fact his point was very clearly proven. Mikey was about to follow when he saw that Leo was still chilling on the cot.

Seeing that his attention seemed planted on Donnie, the jokester asked the question that he already knew the answer to. "You coming?"

Leo raised an eye ridge, "To hear Casey brag about his genius and watch Raph try to beat the both of you? Nah, I'm good." His gaze strayed back to the genius. "Just... Gonna hang with Donnie for a while."

Mikey gave his brother a knowing grin and then headed towards the door. "Let me know if you need me!"

"I won't!"

"We'll see!" With a salute to the chuckling leader, Mikey sashayed his way out of the room; the jokester pausing just long enough to pull the door shut behind him.

It was approximately seven minutes later before he went bounding back in to grab his popcorn and practically destroyed a few vials of only-Donnie-knew-what along the way. He didn't give a second thought to the screams of fury at his departure and none of them noticed the satisfied grin that hid beneath his ducked head as he fled the scene.

The broken vials were the perfect reason for Leo to make an excuse to interact with him and, if the soft smile on Donnie's face when Leo offered to help was any indication, the genius's insecurities were in good hands.