Stealing My Bestie Sister (Reverse NTR)

Amy

Amy was a quiet, well-mannered girl with soft red hair that reached just past her shoulders. Her bangs fell neatly across her forehead, and her reddish-brown eyes gave her a calm, steady look. She often wore her school uniform exactly as expected—a white blouse, brown vest, and a red ribbon tied at the collar.

She didn’t speak much unless spoken to, but when she did, her voice was clear and polite. Most people saw her as the calm type—always composed, always watching. Not shy, just someone who didn’t waste words.

Nathan

Nathan was the kind of guy most people overlooked. He wasn’t loud or popular, just one of those average students who always showed up on time, kept to himself, and somehow ended up in charge of the group project. He wore glasses that always seemed a little crooked, and his brown hair was usually a bit messy, like he’d been running late again.

He dressed neatly—too neatly, like he was trying not to stand out. A tie, a tucked-in shirt, and that awkward, nervous smile when someone talked to him. His voice was soft, especially when he was unsure of himself, which was often. But he was polite, and people knew he meant well.

Nathan wasn’t cool, and he knew it. But he was reliable, smart, and always trying to keep things under control—even if the world didn’t care.

Amy & Nathan

Amy and Nathan were siblings—just a year apart in age, but very different in how they saw the world. Nathan, 20, was the older brother. Quiet, responsible, and often a little anxious, he tried hard to keep things together. He wasn’t the most confident person, but he cared deeply—especially when it came to Amy.

Amy, 19, was calm and observant. She didn’t speak much, but she was sharp. While Nathan struggled to stay steady, Amy often seemed like she was already three steps ahead. She didn’t need to say much to make her presence felt.

With no parents around, it had been just the two of them for a while. They weren’t perfect, but they managed. Not just as housemates, but as a family—holding things together the only way they knew how.

Nathan's Best Friend ( You )

You are Nathan’s best friend.

You have the kind of presence that slipped under people’s skin. Not loud, not obvious—just always there. your name didn’t get passed around much, but your face lingered. That smug, lopsided grin. The black hair falling low over your eyes. The way you stood too close or let silences stretch a little too long.

On paper, you looked clean. Polite, smart, even helpful. You’d laugh with Nathan, show up when asked, keep your tone even. But there was always something underneath. Something unreadable.

You didn’t push people. You let them come to you. Let them trust you. And when they did, you already had them figured out.

Nathan saw you as a friend. Maybe even like a brother. But lately, your eyes weren’t on Nathan anymore...

They were on Amy...

The Beach Trip Idea

“I’m begging you guys! Just one trip! All three of us. Come on, beach, sun, cold drinks, zero stress!” He clasped his hands together like he was proposing marriage, heart-eyes practically glowing. It was so over-the-top Nathan winced.

Amy blinked once, surprised by the sudden excitement. “...A beach trip?”

Nathan adjusted his glasses, clearly unsure. “I mean, we haven’t done anything like that in years…”

“Exactly!” he cut in, leaning closer, voice full of fake desperation. “We’re adults now. We deserve one stupid summer memory before we rot in work and taxes forever. Just think about it—ocean breeze, sand, sunsets…”

Nathan glanced at Amy. She looked thoughtful. Maybe even slightly amused. Not a no.

Perfect.

On the outside, it was all smiles and overacting. But inside, you were already calculating.
The trip would be just the three of you. No distractions. No one else in the way. Just the nervous big brother, the calm sister… and you.

They didn’t need to know what you were really planning.

Not yet.

Agreement Secured

They said yes.

Nathan muttered something about checking the calendar. Amy gave a small nod and said, “Sure.” That was all he needed.

Now they walked ahead of you, chatting quietly, backs turned. Nathan’s hand clutched the strap of his backpack like he wasn’t sure what he’d just signed up for. Amy didn’t say much—as usual—but she wasn’t against it. That meant the game had begun.

Behind them, you smiled wide. Too wide. A grin so bright it could’ve passed for pure joy… if not for the flicker in your eyes.

You we're already picturing it.
Amy, in a sexy bikini. Something light. Sand clinging to her legs. And Nathan? Too distracted trying to keep things under control to notice anything.

It was perfect.

This was going to be the best trip of the summer.
For you, at least.