AN: This was inspired by two conversations I've had recently; One about fictional brothers and which one gets the better end of the deal, and the other about what Sasuke and Itachi are arguing about. It's been sitting in my documents for months now, and I've just now gotten around to publishing it. This makes use of a couple other fandoms I'm in (Supernatural and Fullmetal Alchemist, to be precise), but it isn't a crossover.

*Spoiler Warning, though (ironically) not for Naruto. If you aren't up to date on Supernatural or aren't familiar with how the Fullmetal Alchemist manga ended, though, then they'll be spoilers for those. (And if you don't read/watch/care for those two series, than don't worry about it, you don't really have to be familiar with them)

Summary: Sasuke asks a question that's been plaguing younger siblings for decades. Itachi answers as only a big brother could. AU in the sense that both Itachi and Sasuke are alive, happy, and able to play videogames together.

~Brotherly Logic~

"Why the hell am I always Luigi?" Sasuke demanded, practically throwing his game controller down and glaring at his older brother.

Itachi didn't even take his eyes off the television screen. "Hmm?"

Sasuke crossed his arms angrily and slumped back into the couch. "You heard me. Why. Am I. Always Luigi?" he seethed. "It doesn't even matter what game we're playing - you always take Mario, and I'm stuck with Luigi! It's not fair," The last part was muttered under his breath, but Itachi heard it anyway.

"Do you have any idea how petulant you sound?" Itachi sighed, still not taking his eyes off the bouncing red-and-blue clad plumber on-screen. "Don't be a child. If you don't want to be Luigi, pick somebody else."

Sasuke made a disgusted sound deep in his throat. "Like who?"

"There's always Toad." Itachi replied mildly, his mouth twitching just a little bit - just enough for Sasuke to see, which ticked him off further.

"I don't want somebody else, and I certainly don't want Toad!" Sasuke fumed, pointing an accusing finger at Itachi. "Nobody wants Toad! He's Toad! Even his name is stupid! I want Mario, but I can't play him because you're always playing him! And while we're at it, why the hell am I always player two, hmm? Who died and made you player one for eternity?"

Itachi remained infuriatingly impassive at this outburst, and barely spared a glance at Sasuke out of the corner of his eye. "Next thing you know, you'll be saying I take the 'good' controller, too." he said dully.

Sasuke's head shot up. "Yeah, yeah you do! Every time, and-"

"That's because it's my controller. I bought it. And it's not any better than the one you usually use." Itachi cut in. "What's gotten into you today? It's not my fault you missed the jump, why are you taking it out on me? You've been hanging around Naruto too much, he's rubbing off on you."

"Don't turn this around on me!" Sasuke snapped. "At least Naruto and I take turns picking characters. You don't even want to flip a coin or play rock-paper-scissors for it."

"I can't believe you're comparing me to him. And we've been playing this way for years, why are you just now throwing a fuss?"

"Exactly! We've been playing this way for years, and I haven't gotten to play Mario once! If you ask me, you're the one being childish!" Sasuke said, crossing his arms sulkily.

Itachi actually laughed at that, much to Sasuke's chagrin. "I'm being childish? I'm not the one throwing a tantrum in our living room like a five-year-old." He sighed at the angry growl Sasuke aimed at him, and added "What exactly do you want?"

"I want to know why I'm always Luigi!" Sasuke cried, grabbing one of the couch's throw-pillows and pelting it at Itachi. It connected squarely with the side of his head, blocking his view for half a second - which was all it took to make poor Mario walk straight off a cliff.

Both brothers froze as the familiar little tune played to tell them the character had died; Itachi staring at the screen with an unreadable expression, Sasuke with his arm still hanging midair from the throw.

Finally, after a few tense moments of continued non-movement, Itachi sighed and put his controller down.

"You want to know why I'm always Mario," he said bluntly, turning slowly to face Sasuke.

Sasuke's eyes widened minutely, having expected Itachi to either reprimand him, throw the pillow back, or flick him in the forehead as he usually did when Sasuke did something to annoy him. Itachi actually answering his question was at the bottom of his list of expectations.

Upon seeing Sasuke's reaction, Itachi rolled his eyes and crossed his arms, then sighed in exasperation and made a 'Well?' gesture with one hand, so Sasuke took that to mean he was safe for now.

He still made sure he was out of arm reach when he sat back down, though. Just in case.

"I'm always Mario and you're always Luigi because, in the grand scheme of things, I'm Mario and you're Luigi." Itachi said calmly, as though he was explaining something very serious to a small child.

Sasuke stared blankly at him. "Uh..what?"

Itachi rolled his eyes and sighed again. "If we were the Mario brothers, I'd be Mario and you'd be Luigi. It's that simple." he said, gesturing between the two of them. "Mario." - he pointed at himself - "Luigi." - he pointed at Sasuke - "Simple."

"What...? Why?!" Sasuke said, and scowled. "Just because you're older? That isn't fair! You know Mario and Luigi are twins, right?"

Itachi gave Sasuke the look of long-suffering older brothers everywhere and straightened up some. "Life is rarely fair." he said dismissively. "Mario is still the older twin. And no, not just because I'm older. Because it's the status quo, and that's just the way it is."

"Are you even listening to yourself? In what universe does that make sense?" Sasuke demanded, caught between amusement and annoyance. "What are you even saying?"

"I'm saying," Itachi said stiffly. "That if we were the Mario brothers, I would be Mario; the brave plumber dashing off to rescue princesses from dragons, while you - Luigi - lie scared in some mansion somewhere trying to hunt ghosts and being a generally weird dork."

Sasuke stared. "You're joking." he deadpanned.

Itachi smiled serenely back. "I'm not," he assured him.

Sasuke snorted. " I'm Luigi because, in your warped sense of reality, you're the gallant older brother that gets all the attention? Do you have any other examples of your alleged superiority?"

"As a matter of fact, I do." Itachi said pleasantly. "Do you want to hear them?"

"Do I have a choice?" Sasuke groaned, tilting his head back against the couch so he was staring at the ceiling.

Itachi ignored him and cleared his throat dramatically. "If this was Supernatural and we were the Winchester brothers, I would be Dean - the charming (and much better looking) hunter carrying on the family business, killing monsters and picking up the messes you - Sam - have caused while running off soulless or consorting with demons and wallowing in your own self-pity."

Sasuke blinked and turned his head to Itachi, who looked like he was about to burst with his own self-righteousness. "You're actually serious." he said in disbelief.

Itachi carried on as though his little brother hadn't said anything.

"If we were the Elric brothers, I would be Ed - the ever-clever (and again, much better looking) Fullmetal Alchemist trying desperately to get his little brother's body back while you - Al - are stuffing cats into your suit of armor and being a generally whiney pain in the ass."

Sasuke picked up the second throw-pillow and buried his face in it, trying to drown out Itachi's voice. It didn't work.

"If we were-"

"Okay okay, I get it." Sasuke scoffed, sitting up. Itachi carried on anyway.

"In short, I'm the cooler, better older brother, therefore I get Mario. End of story." Itachi said smugly, smiling sweetly at his little brother.

Sasuke gaped back at him with his eyebrows raised. "You've put some thought into this."

"Not really. It's pretty obvious." Itachi replied with a shrug, picking his controller back up.

"And I can't really argue with your logic." Sasuke said thoughtfully.

That made Itachi pause. "Oh?"

"Mmmm-hmmm, it really does make sense."

Itachi narrowed his eyes suspiciously. "I'm glad you see things my way."

"Yeah, yeah I can see it." Sasuke said, nodding. "I mean, if you're Ed and I'm Al, then you're the hot-head who picks fights, loses two limbs and ultimately never gets one back, loses his ability to do alchemy by the end, gallantly sacrifices an arm just to keep me alive, and stews in his own guilt for causing me to lose my body while I'm the reasonable one that ends up with the same alchemical abilities you have, has a badass suit of armor to run around in when I don't have a body, and who gets my body back AND can still do alchemy by the end of the series."

Sasuke noticed Itachi's mouth had pursed into a tight line, but he didn't interrupt, so Sasuke continued.

"If you're Dean and I'm Sam, then you're the one who oh-so-kindly sold your soul just to bring me back to life, got tortured in Hell for forty years and kick-started the apocalypse, and let a bunch of terrible things happen to you just to look out for me, while I get cool psychic powers, a string of hot girls, and lovely flowing hair."

"Since when do you care about hair?" Itachi protested abruptly.

"And if you're Mario and I'm Luigi, then you're the kinda tubby guy who's basically doomed to repeatedly rescue a girlfriend who's obviously not as into you as you're into her for the rest of your life, while I'm the more endearing one who is also more intelligent, faster and can jump higher yet remains more humble and quieter about it, and has a girlfriend with a much better security system than yours does. Does that about cover it?" Sasuke added as an afterthought, sounding almost cheerful.

Instead of answering the younger Uchiha, Itachi picked up his controller again, his face remaining neutral as Sasuke mimicked his earlier smug expression, resting his chin in his hand and smirking at him.

"I suppose that's one way of looking at it," he said finally with a tone of nonchalance. "All of that seems more like a matter of opinion to me, but..."

"No more than yours was." Sasuke said, still smirking as he picked up his own controller.

"Mine was not an opinion," Itachi sniffed, affronted.

Sasuke rolled his eyes and turned to him again. "Why is mine an opinion and yours not?"

"Because I'm the oldest, and that means I'm always right." Itachi responded waspishly.

Sasuke scowled and froze for a second, but waited until Itachi had started the game again before he said anything.

"You know what else all those younger brothers have on the older ones?" he asked casually, keeping his eyes on the screen.

Itachi barely acknowledged him. "What?"

"They're all taller."

Once again, poor Mario plunged to his death as Itachi jerked his head to glare at Sasuke, who was smirking maniacally and pointedly not looking at him.

Sighing, Itachi put his controller back down and closed his eyes. Once he had counted to ten, he picked up the pillow at his feet and hit Sasuke with it. When that didn't work, he moved on to trying to smother him.

AN: There were several other sets of brothers I wanted to use for Sasuke and Itachi's 'the reason you suck' speech, but they either didn't always fit the criteria (namely Sasuke's height crack) or I couldn't picture both Uchiha brothers knowing who they were (whereas I really could see them both watching Supernatural and Fullmetal Alchemist together).

Thanks for reading! :) Reviews and comments are always appreciated!