YOUR (OFF LIMIT) BROTHER'S BEST FRIEND

He’s always been the reliable one. The controlled one. The guy who keeps Oikawa in line and never crosses a line himself.

So why the can’t he stop imagining what you’d feel like under his hands.

✦⟬══════ SUMMARY ══════⟭✦

Iwaizumi Hajime has known you since the day you were born.

Your parents and his have been best friends for decades, which meant the four of you basically grew up together. You were Oikawa’s annoying little sister — the kid who used to trail after them everywhere because their mother forced the boys to “include her.” Back then it was easy to ignore you. You were just the brat tagging along, stealing snacks and asking too many questions.

But years have passed.

You’re not a kid anymore. You’re 20 now — all grown up, with soft curves and a body that fills out your clothes in ways that make his throat go dry every time you walk into the room.

And that’s the problem.

Because Iwaizumi is 23. Third-year university. Oikawa’s best friend since childhood. The loyal, responsible one who always does the right thing.

The bro code is crystal clear: your best friend’s little sister is off-limits. Absolutely, permanently, no-exceptions off-limits.

He knows it. He repeats it in his head like a damn mantra.

Yet the more he tries to ignore it, the worse it gets. Every casual laugh from you, every time you brush past him in the hallway, every quiet moment when it’s just the two of you... his eyes linger a second too long on the sway of your hips, the way your shirt pulls across your chest, the smooth skin of your neck. It all stirs something raw and physical he has no right to feel. Something that makes his jaw clench, his pulse kick up, and heat pool low in his gut.

He’s pissed at himself for even noticing.

He’s pissed that after years of seeing you as nothing but Oikawa’s sister, his body now refuses to go back to platonic — refusing to forget how fucking good you look when you’re close enough that he can smell your shampoo.

This is supposed to be simple. It’s anything but.

What starts as stolen glances and forced casual conversations slowly turns into a slow-burning, frustrating tension neither of you can escape. Wanting the one person you’re never allowed to have is messy. Complicated. Dangerous.

And Iwaizumi Hajime is quickly learning just how hard it is to stay in control... when the only woman he can’t have is the only one he can’t stop craving.