I was randomly inspired to write this at around ten at night while sitting on my ass at work. I place all liability on my Quadratic Functions homework, my lack of sleep, and my friend Black-Haired Girl. Also, I don't own Initial D or any of these characters. If I did, however, Keisuke would not be enrolled in a junior college like me.

Why was Keisuke growling at his textbook?

Ryosuke resisted the urge to turn away from his homework and locate the reason for the odd noise. The rotary expert was supposed to be studying his own schoolwork; he had to sit for an entrance exam in less than a week, and between college and overseeing the Red Suns he had managed to get behind in his studies. It was a mistake that he normally did not succumb to, but a lot that he had once considered 'prohibited activity' was fast slipping into the category of 'tolerable in limited quantities.'

Take Keisuke, for instance.

Normally Ryosuke's room was sacred space and the obnoxious blonde was not allowed within five feet of its door between the hours of six and nine in the evening, because that was the older Takahashi brother's self-designated study period and Keisuke was nothing if not distracting. The FD driver had an incredibly difficult time sitting still for longer than ten minutes and often used his brother as a sounding board for his upgrade planning and troubleshooting.

Ryosuke had no qualms with assisting in the FD's tuning so long as these brainstorming sessions did not take place while he was trying to find the derivates of quadratic functions. And since he often spent hours at a time buried in his textbooks this almost always became a conflict of college workload versus racing.

Keisuke plus homework equaled no studying accomplished.

To eliminate the need to decide between RX-7s and Calculus Ryosuke had chosen the simplest solution; he had removed the variable of his bored younger brother. Unfortunately the most obvious answer had not proven the most effective in this particular scenario.

Keisuke had resented the restrictions imposed on him of not having access to any area of the house that he deemed his territory. Between the ages of nine and eleven he had determined that because Ryosuke was his brother, Ryosuke's room was his as well. The FC driver had not been able to convince him of the flaw in that logic.

Keisuke did not equal Ryosuke.

The Mazda drivers did not fight often, but when they did it was a loud and altogether unpleasant affair that normally ended in an unstated but mutual compromise. This had been one of those rare occasions. Two hours after the argument had commenced Keisuke had been allowed back into his brother's room on one condition; if Ryosuke was to study then Keisuke was to study, as well.

This brought Ryosuke full-circle to his current dilemma. The uphill specialist was still snarling quietly at whichever of his junior college course books he had hauled into his brother's room, and Ryosuke had chosen to ignore the differential equation that sat, half-completed, on the desk in front of him to speculate on why the blonde was making such an odd noise.

Keisuke plus books equaled general aggravation.

Ryosuke picked his pencil up and frowned. It was stupid really, because the common sense side of the FC driver's brain--the side that was responsible for his intellectual prowess, no doubt--was attempting to shove his focus away from his younger-sibling-the-distraction and toward the nine-step Calculus problem awaiting his attention.

The more human part of his agile mind--the half that seemed to be reserved almost exclusively for contemplating the almost bizarre way that Keisuke often behaved and thought--seemed stuck on the ominous growling emanating from somewhere over his left shoulder.

Ryosuke had a decision to make. Either he ignored the distraction, admitting to himself that normally his brother's strange quirks were altogether unimportant and trivial at best, or he gave in to his natural curiosity and investigated. The former of the two options was obviously the more responsible route; the latter would set the undesirable precedent that Keisuke's distracting behavior would earn attention from his brother.

Then again it was public knowledge that Ryosuke had always been a pushover when it came to the younger Takahashi's antics, and Keisuke often exploited that weakness mercilessly. Anyone who thought for a moment that Ryosuke was any smarter than his brother was sadly mistaken. Keisuke was simply uninterested in scholastic achievement. No, the uphill specialist was far more gifted in his powers of persuasion and attention to instinct than performance in tests and exams. He chose to convey an apathetic sense of intellectual inferiority. It worked well for him.

It suddenly occurred to Ryosuke that he spent an inordinate amount of time contemplating Keisuke Takahashi. It seemed to border dangerously on infatuation, but the premedical student knew that wasn't the case. Not quite. And he felt the familiar rush of embarrassment as his dignity supplied for him that he was not in fact obsessed with his little brother's comings and goings, but merely observant.

Hirofumi often pointed out rather unhelpfully that in order to think like Ryosuke one had to set aside approximately fifteen percent of his or her brain function simply to mull over everything that Keisuke did. The part of this observation that annoyed Ryosuke was the validity that it held. It didn't bother him that he devoted so much mental activity to the blonde; it unnerved him that this attention to Keisuke was so obvious to everyone around them.

Ryosuke minus Keisuke equaled an imaginary number.

Fujiwara seemed to have picked up on it, as well. For as much as Keisuke jeered that the 86 driver was mentally challenged--earning the formidable downhill specialist the nickname 'Space Case'--Takumi was far more observant than anyone gave him credit for. Not only had he pinpointed the odd infatuation that Ryosuke seemed to harbor for his brother, but he almost seemed to view it as a challenge.

Competition wasn't an adequate enough word to describe the fierce rivalry between Keisuke and Takumi. It rang true in every interaction they had; something as mundane as passing a wrench between them in the garage became an unspoken battle of will, a test of hierarchy and rank. It was ridiculous but very revealing. Neither young man could back down, Takumi due to the deep set pride his father had instilled in him and Keisuke because of sheer arrogance.

Fujiwara equaled the opposite of Keisuke.

It was akin to watching wild animals fight for social dominance and alpha-beta hierarchy. Ryosuke would not intervene. They had to sort the matter out for themselves, but the Project D leader had set down some very basic ground rules.

Both drivers would speak to each other like rational adults.

Both drivers would respect Ryosuke's decisions regarding their positions on the team.

Both drivers were absolutely forbidden to race one another until Project D was disbanded. What they did after that was not his responsibility, but for the meantime he did not want the headache involved with either losing to the other. They had more important goals to accomplish than a racer's feud.

Unfortunately Ryosuke was well aware of the tension that these restrictions placed on his brother. Keisuke was extremely brash and quick-tempered when properly provoked, and everything about Fujiwara seemed to piss him off. When he wasn't bashing the other racer's outdated vehicle he was busy discussing at great length how mentally deficient the tofu driver was with Kenta or any other interested party. It was embarrassing to listen to, but Ryosuke understood the logic behind the immature behavior.

Keisuke felt a compulsive need to prove himself worthy to the team for having been bested by Takumi not once, but twice. He also saw the younger racer as a threat to the attention he received from Ryosuke, and that perception was a dangerous one. Keisuke tended to handle competition the only way that he knew how--complete annihilation. And since Ryosuke had prohibited a direct race, his only other option included physical violence. It was a defense mechanism.

Fujiwara plus Ryosuke equaled Keisuke minus Ryosuke.

The longer the team had gone on, the more Ryosuke had noticed the barely-restrained rage in his brother's normally confident and arrogant demeanor. Fujiwara had noticed the subtle shift in control as well, and he was capitalizing on it. It was probably a much-appreciated difference in their usual interactions. For the first time since encountering Keisuke, Takumi finally had some power over the slowly-boiling hatred between them.

Ryosuke honestly couldn't blame the Toyota driver. He had never been on the receiving end of Keisuke's ire and he would never invite that experience. The last time that he had personally witnessed the blonde lose his composure and lash out at someone had been almost four years ago, and the teenager had sent a rival gang member to the hospital with a broken arm and a concussion. The fight had lasted less than thirty seconds. Keisuke was frighteningly efficient when he lost control.

The more that the FC driver tried to fairly balance the two racers the more he felt his control of the situation lessening. It was as if he'd held the reigns of violence in his hands and been made to watch helplessly as they slipped from his fingers. He understood that their team would not succeed divided as it was, but he could not for the life of him figure out how to remove himself from their rivalry. Obviously he was the differentiating factor. He simply couldn't see a viable method of factoring himself out of the equation.

Ryosuke divided by the product of Keisuke and Takumi equaled an undefined quantity.

The brunette sighed in frustration and decided to give up on his assignment. There was no point in continuing to stare blankly at an equation that would not solve itself. Ryosuke turned to stand and stretch his cramped legs and found his brother standing over his shoulder, frowning down at his notebook. Keisuke chewed his lower lip slowly in concentration before reaching over without a word and plucking the pencil from his sibling's left hand.

The FD driver scratched something onto the page in his barely legible handwriting and set the pencil down. "That equation is prime," he said quietly, the disbelieving tone to his voice suggesting that he had just surprised himself. Ryosuke's brown eyes flew back to the equation that he had been daydreaming over. He felt a flash of shock race through his mind as he realized that not only was the blonde correct, but it was such a simple answer that Ryosuke had simply discarded it as being incorrect.

Shock quickly gave way to curiosity, as was often the case with regard to his little brother. "How did you know that?"

Keisuke shrugged nonchalantly and pointed to where he had been sprawled across Ryosuke's bed for the past two hours. In the center of the bedspread was the FC driver's Calculus book. "I was too lazy to go grab my Trigonometry book from my car so I read yours."

Ryosuke gave his brother an incredulous stare. "Keisuke, that's a Differential Equations Calculus textbook."

The blonde's eyebrows shot up. He squinted at the cover and frowned. "So it is. Well, it made sense to me. We just went over those," he said, gesturing vaguely at Ryosuke's assignment and breaking into a loud yawn. "I'm crashing for the night. See you in the morning."

Ryosuke nodded absently, staring stupidly down at his brother's scribbled, cramped writing among the otherwise neat and tidy numbers and letters on the page.

Prime equations cannot be factored...

The leader of Project D distantly heard Keisuke shuffle towards his bedroom door, pause, then shuffle back to the desk. His brother leaned over his shoulder and slid an arm around his chest, giving him a brief, one-armed hug. "Love you, Ry," he said quietly, and then the blonde was gone. The brunette heard his door click closed and sighed.

Ryosuke felt a slow, wry smile curve his lips. Of course Keisuke would be the source of not only his current dilemma, but the solution as well. He ran a hand through his hair and slumped back into the chair, staring up at the pristine white of his bedroom's ceiling.

He was the variable that could not be factored out of either Keisuke or Fujiwara's lives to simplify things. How ironic. Ryosuke pushed away from the desk and stood, stretching languidly.

Keisuke plus Calculus minus studying equaled a differential outlook on an unfactorable equation in three variables.

Ryosuke would never look at math the same again.

And neither will I.