FORENOTICE: This story will get slightly alter universe-ish, thanks to my having only seen the anime for this series, and very, very little of the manga so far. It will work for the plot, so hopefully it will work for you guys, too.

The first time he dunks the ball, he's eleven years old.

He's just hit a major growth spurt and he's pretty much towering over all their classmates with his 170 cm. His arms are long and lanky, lined with strong, sinewy muscle from all the years of playing basketball.

The jump he makes to reach the basket is impressive, and his dunk itself twice more.

He grabs onto the hoop after the ball is through the net, and pulls himself up by the metal so he can arrange himself a securer landing.

When his feet touch the ground again, he turns to look at her, his eyes shining bright with mirth and triumph.

"Sacchan, did you see me just now? Did you see?!"

For a second, all she manages to do is just blink in dumbfounded fascination as what she has seen slowly registers in her mind. He's only eleven, although he's already becoming so tall, and he can pull off that impressive move that she's only seen the most talented of players do on TV.

She nods numbly and he releases an excited shout, thoroughly ecstatic.

The first time he can pull off a dunk, Aomine Daiki is eleven years old.

That same day, his best friend can't get out of her mind how breathtakingly cool she believes he looked when he had reached the ring, and pulled himself up on it before jumping down in an almost graceful form.

When they are little, she thinks of him as a brother.

They're always together—just like siblings—and he's her favourite playmate. So it only makes sense that she feels as close as she would if they were related by blood.

He's definitely her brother in her eyes, even though they have different moms and dads. If you were to ask her whether he was a big brother or little brother to her, on most days she would be absolutely certain that he's definitely her little brother.

The fact she's a few months older than him is inconsequential. What makes her think of him as her little brother is the fact he always forces her into situations where she needs to be the voice of reason.

He's a boy, he's mischievous and he's a natural at constantly getting them in trouble. So it's up to her to talk him out of the most dangerous games and the most risky of stunts he wants to pull. It's usually her role to act cute, harmless and repentant when they get caught by a grown up for some of their pranks.

She can't recognize it as what it is because of her own immaturity, but she willingly acts as his buffer. Most of the time she shields the world from his wackiness and crazy ideas, mediates the most unacceptable ones and helps him turn them into something bearable. She watches over him from close by, never letting him out of her sight. She is protective of him the way she's protective of her plushies and small animals which can't protect themselves.

She's his big sister and, although it's an inconvenient role most of the time, she plays it gladly.

He's quite the handful and he has a tendency to overdo things, but every day with him is fun and full of adventure.

Every day is worth living.

And it's his endlessly brimming with energy character that makes it possible.

She calls him Dai-chan, and in her eyes, he's her troublesome little brother from another family whom she loves and adores.

As for Daiki, being thought of as someone who needed constant caring for was more than convenient.

He never needed to worry what he would do if he got caught pulling off this prank or that because Sacchan was always there right behind him with her big round eyes and cute face to pull them out of a serious lecture.

He never wondered what he'd do if he forgot his homework or didn't have time to do it at all, because Sacchan always does hers and always lets him copy.

He never needs to ask other people to lend him money when he forgets his on the table at home, because Sacchan knows how forgetful he is and always asks her mom for enough for lunch for two.

He thinks of her as the sister from another family who is always there to help him whenever he needs her.

And although she takes the role a bit too seriously—by the time they're ten, she has completely convinced herself that he can't even tie his shoelaces without her—to the point that she sometimes ends up being annoying with her endless nagging and preaching, Daiki is very grateful for having his big sis with him. Her presence itself is soothing and knowing that she's around simply reassures him that everything would be all right.

On almost every day of the year, Sacchan is the big sister and Dai-chan is the little brother she is constantly looking after.

However, there are those rare moments when things just… happen. Things happen and the tables get reversed so fast, so unexpectedly and so successfully that it's almost enough to give her whiplash.

The times when she sees him as her big brother—with him looking after her instead—are so few and rare, but so intense and poignant in her memory that she can point out each and every single one of them.

Being best friends despite their different genders had never been a problem when they were little. But as they grow up and start attending school, the fact they are a boy and a girl, who aren't related by blood and are as close as siblings starts becoming problematic.

It was problematic as far as the fact that Satsuki couldn't take part with the boys in their boy-games because the other boys didn't want her in. She couldn't include Dai-chan in her games with the girls because the other girls didn't want to play with him. And whenever either of them tried to make an effort to include the other into their midst, the group of elementary schoolers reacted.

One time, while Dai-chan was sent after a ball that flew too far away, the boys who had been playing with him rounded on the pink-haired girl and started picking on her for constantly hovering around the playground when her best friend was there.

They were pulling her braids and calling her names, trying to chase her off back to her girlfriends where she "belonged". Their ridicule and the painful tugs on her hair quickly reduced the girl to tears.

It was like this that Daiki found his playmates picking on his almost-sister.

When he saw what was going on, the blue-haired boy saw red.

What right did those little rascals have to pick on Sacchan? What had she even done to them to deserve such treatment? She wasn't getting in anyone's way as long as she stayed off the court. So what the hell was their problem?

He got rid of her bullies so fast and so efficiently that the little girl was forced to reassess her opinion of her childhood friend. She had never seen him so fierce and protective of her.

Frankly, it warmed her heart. It made her see that their bond wasn't a simple give-and-receive from her to him.

Once all her assaulters were all gone, Daiki breathed out a deep sigh before turning around to take a good look at her. Her eyes were wide and her jaw was slack as she stared back at him, blinking dumbly. His lips set in a thin, displeased line while he reached out to wipe a smudge of dirt from her chubby cheek.

It was a simple enough gesture but it was enough to break the proverbial dam. She doubled over and clutched her knees then, crying from relief and gratefulness. It made Daiki uncomfortable—especially since he didn't understand why exactly she was crying.

The incident makes Satsuki aware that her little brother could step up and act like the older, more responsible, stronger, of the two of them whenever need called it.

The first time Satsuki gets bullied for being friends with him, they're nine years old.

When they are kids, they don't even notice the differences of their genders. They don't matter.

After all, why should Daiki care that his best friend is a girl if he can play with her most of the same games he could with his guy friends as well?

Why should Satsuki care that her best friend is a boy if he can find them things to do together that are fun enough for both of them?

They remain blissfully oblivious to their differences for a long, long time.

The situation starts changing around the time when they graduate from elementary school.

It starts changing because Satsuki can no longer meet her best friend's eyes when he's standing next to her unless she tilts her head.

Daiki is twelve years old when he goes through his biggest growth spurt.

At the end of elementary school, he already towers a good head above her. Not only is his body larger, his limbs lankier and longer, but his physique is becoming very obviously different from hers.

Their difference in height only makes it that much more obvious.

In the last year of elementary school, Satsuki finds it hard to think of Daiki as her adorable little brother who used to always cause mischief. After all, it's absolutely impossible to associate the word "little" in any way with someone 172 cm tall without a certain amount of cognitive dissonance involved.

The other major event that destabilizes her world view is the change of his voice.

It's not a sudden thing. His voice starts changing gradually, over the course of a week. For a while, he believes he's caught a cold which has weakened his vocal chords to the point that he lost his voice for a good day or two. When he starts talking again, it's a croaky and unstable sound, and he knows it will be a while until his voice is his own again.

A couple of weeks later, his "cold" is nowhere to be found anymore and his voice is stable again.

She doesn't notice it immediately. It's when he asks her something while peering over her shoulder, his lips right next to her ear, that she realizes.

"Dai-chan, did your voice change?" she asks as she turns her head to face him.

He glances at her, confused for a little while, his eyes rolling up to the ceiling of their classroom in thought.

"Did it?" he asks aloud, pondering the matter himself.

Satsuki nodded slowly, still staring intently at him with that searching gaze of hers.

He shrugged.

"I guess it did." He put his arms behind his head as he looked down at her from his vantage of standing next to her seated form. "What does it matter anyway? It's still my voice and it's hardly different."

It didn't really matter, per se. He was right—it was still his voice and he was still her Dai-chan.

However, she couldn't agree with him that his voice was 'hardly different'.

To her ears, it was very different.

No longer did he have the slightly high-pitched, almost-androgynous voice of a child.

The voice he now used was not that of a child. When he spoke now, Dai-chan spoke to her with the voice of a boy.

He was starting to change.

Changes scared Satsuki. They did because they made her worried.

She worried because she knew that his love for basketball would only make the difference in their heights bigger, the increase of testosterone in his system (among other things) would make his voice deeper and he would keep growing.

She worried because she didn't want him to keep growing and leave her behind somewhere on the way of getting there.

But thinking in this way is silly, she reminds herself. Dai-chan wasn't going anywhere. He was right there and he said it didn't matter. He said that the changes didn't matter.

So she would believe him. She would choose for the changes not to matter for her either.

She would put her hands over her eyes and claim that everything is all right, despite the anxieties that stirred in her every once in a while.

The last major event that solidifies their difference is when she hits puberty, respectively making her chest size grow.

And, boy, did her chest grow.

By the time they graduate from elementary school, she wears bras and they are already C cups. Slowly, but steadily, her body starts adopting the curves of a girl.

Her breast size doesn't really bother her. The jealous looks from some of the girls who don't know her don't faze her in the least. Satsuki has always had a cute face so she's used to being pampered and envied.

What perturbs her is that she starts catching Dai-chan staring at her chest more and more often the larger they grow.

She doesn't particularly care that he's staring. He's always been somewhat rude and very selfish, always doing whatever he wanted. That was nothing new. She didn't mind the act of the staring itself but rather the way he looked at her in those moments.

When she caught him eyeing her chest, she knew that they weren't Sacchan and Dai-chan, best friends since before she could remember. In those evanescent moments, he was a boy and she was girl and that scared her.

She didn't want him to think of her as a girl because she didn't know how to be anything other than his big sister, his personal caretaker. The only person she knew how to be was Momoi Satsuki, his best friend and collateral in all his earlier mischief, his most avid and quiet supporter.

She couldn't be anyone else but that person.

And if he could no longer accept that as her role, she worried that perhaps he had already changed and moved out of her reach before she could help it.

Thoughts of this sort make elementary school graduation a painful ordeal. They don't meet over the summer as often as they used to and that alarms her.

When she thinks all is lost, he comes by her house one day. He asks her where her parents want to send her for junior high.

His question catches her off-guard. She hasn't really given it any thought.

"I want to go to Teikou," he confesses earnestly, his eyes downcast.

She looks up from the drink in her hands she's stirring with her straw. She notices that he doesn't meet her gaze.

"Teikou Middle School?" she echoes. He nods. The way he's still avoiding looking into her eyes unnerves her and reawakens her earlier anxieties. "Why Teikou?"

"Teikou is famous for having the best middle school basketball team in the country. I—" He's twirling the straw of his drink so violently that he's crushing it between his fingers. "The only thing I'm good at is playing basketball. I love it and I want to play with those guys. So I'll join their school to be part of their team."

Satsuki makes a thoughtful hum at the back of her throat while she stares him down. She guesses it makes sense. Dai-chan was the best when it came to basketball and he played the game with so much passion she envied him. It would be only natural for him to join a school with a strong basketball team.

That's when he looks up from his fingers toying with the straw to lock his intense cerulean gaze with hers.

"What about you? Where will you go, Sacchan?"

Those are the words he speaks, but the ones she hears unsaid are slightly different.

He claims he wants to know where she wants to go for middle school, but his shoulders are stiff and his eyes are pleading with her.

Begging her.

Praying that she'll forgive him like she always does.

She smiles brightly at him, a giggle bubbling on her lips.

It wasn't 'where will you go' that she heard when he said it like that. It was 'please come with me to Teikou' that he said to her.

"Teikou, huh?" she reiterates, her voice laced with mirth. "I've heard they have nice uniforms. And I'm sure that the basketball club has never had a manager as cute and thoughtful as me. It would be rude of me to take that chance from them, right?"

The tension begins to leave his shoulders and a grin begins to spread on his features.

She winks at him.

"I guess we're going to enrol in Teikou Middle School in the fall, then."

He does a little fist pump in the air, a loud "yeah!" tearing from his lungs in an exultant call. She grins as she observes his evident happiness.

Gone was the praying look in his eyes, begging her to forgive him for the most selfish of all his requests to her in their lives so far.

Truthfully, though, Satsuki didn't think there is anything to forgive.

She doesn't mind following him to Teikou, because she doesn't care where she studies.

It doesn't matter where they go as long as she doesn't lose her best friend.

Aomine Daiki is eleven years old the first time he dunks the ball through the hoop.

He's twelve when he first tries out for the Teikou Middle School basketball club under the watchful dichromatic eyes of Akashi Seijuurou.

The first time they meet as Teikou classmates is before the entrance ceremony, in front of the large boards announcing the class lists.

He waves at her like he usually does and his voice is cheery like it always is, a huge grin plastered on his face. It makes it impossible for her not to grin back at him while they study the class lists together.

When they enter the school, though, she notices it.

She's no longer "Sacchan".

Instead, he calls her "Satsuki".

It's not really a big deal.

It is her name, after all.

It's no big deal so she doesn't mention it. Doesn't question him.

But she wants to.

It's nothing to worry about.

But she does.

She's uncertain.

It's nothing major, so she doesn't talk about it.

Although she wants to. She wants to so much it almost hurts her physically.

There are few things in this world that Momoi hates. She's generally a bright, optimistic and positive girl. Her personality doesn't allow for much hate to dwell in her light soul.

One of the few things Satsuki hates is changes.

The changes she hates most of all are the tiny little ones, which seem unimportant, but aren't.

It should be no big deal that she's "Satsuki", not "Sacchan", to him now.

Except that it is.

And she hates that, too.

A/N: And so the stage is set! I wasn't really sure what I was doing half the time, but I thoroughly enjoyed the end of this. Comments are awesome and endlessly inspirational.

A thousand thanks to Miss Mugiwara and pidgeon of coarseness for feeding my addiction to this pairing! It needs more love!