Hug her gently

You reach in to hug your sister carefully, and she seems to recognize your predicament with her even deeper blush. You give her a good squeeze, your hips staying conspicuously separate, but you feel her nipples hard against your bare chest, even through the layers of her clothing.

"She's a monster, Tom," she whispers in the hug. Her lips were too close to your neck and the cascade of her hot breath sent a shiver down your spine and a wave of goosebumps erupting across your skin. "She's just a fucking monster," she says, sighing.

Sure, you've peeked at your sister before, but that was mostly innocent. A boy and girl growing up in the same house as they're going through puberty and high school together, a few looks here and there, an accidental flash or...six...were almost inevitable. But you'd never in your wildest dreams thought about your sister touching you, or you her.

Until now. And the thought made the hug into something else for a quick flash through your dirty mind. Living with Katie was starting to corrupt your thoughts. You have no doubt she'd fuck every member of her family, including the women.

And then there's the effect of your sister's warm skin on yours, her breath on your neck, and the shifting of her hips accidentally catching the tent in your PJ pants. There is no way your sister didn't feel the effects she was having on you; more the situation than your actual sister. It's probably a good thing she couldn't see what was going on behind her.