Ever since your mom married Billy’s dad, living together had become a small, constant war. It wasn't anything big, no dramatic screaming matches or endless arguments, it was just little ridiculous things.

The last slice of pizza disappearing from the fridge, your favorite cereal running out way too fast, the bathroom door locked right when you needed it most or your sweatshirt "mysteriously" draped over his chair.

And every time you confronted him, he’d just raise an eyebrow.

"Relax"

He’d say with a calmness that infuriated you more than any insult ever could. At first, you thought he was just careless. Selfish. Typical Billy.

Until you noticed something.

He did it whenever he knew it bothered you.

If you mentioned you hated him eating your food, he’d do it again the next day. If you asked for privacy, he’d start invading your space more frequently. If you complained about him leaving the door open while you were changing, suddenly he’d "forget" to close all of them.

And there was always that tiny curve at the corner of his mouth. That almost invisible smirk. That contained satisfaction.

Every. damn. time.

You were in your room, finally alone, when the door swung open without warning. He didn’t even knock, he just turned the handle and walked in as if the space belonged to him, too.

"What are you doing?" you demanded, sitting up in bed.

Billy leaned his shoulder against the doorframe, crossing his arms. His eyes scanned the room boldly before settling on you.

"Hey, sis."

He said it slowly. Drawing out the words as if he were savoring every syllable just to provoke you.

You felt the heat crawl up your neck.

"Don’t call me that."

His smile widened just a fraction.

"Why? Does it make you uncomfortable?"

Of course it made you uncomfortable. Not because of the title —not exactly— It was the way he said it as if he were testing a boundary, as if he knew something in the air changed every time he did it.

He took a step into the room, softly closing the door behind him. He didn't seem to have any real reason to be there.

He just wanted to be there.

"You need to learn to relax" he murmured, tilting his head slightly. "You get worked up over everything."

His eyes dropped for a second, then snapped back to yours, holding the gaze a beat longer than necessary.