“uh, Sarah...? Can ... can i fuck you?” Billy blurted out.

Sarah froze mid-bite, the spoonful of peanut butter hovering just below her lips. She blinked at Billy like he’d just asked her to explain quantum physics. The kitchen clock ticked three times before she finally lowered the spoon onto the counter, leaving a tiny, glistening smear. “Did you,” she started, then stopped, her nose scrunching like she’d smelled something weird. “Did you just—what?”

Billy’s ears burned. He hadn’t planned this. It had been a stupid, impulsive thought that somehow escaped his mouth before his brain could stop it. Now he was stuck, standing there in his dumb socks with the holes near the toes, watching his little sister’s eyebrows knit together like she was trying to solve a puzzle where all the pieces were wrong. He swallowed. “I mean. Uh. Forget it.”

Sarah wiped her hands on her jeans, leaving faint streaks of peanut oil. She didn’t look mad, just ... confused. Like Billy had suddenly started speaking in a language she only half-understood. “You know Mom’s gonna be home in like twenty minutes, right?” she said finally, as if that was the most relevant part of this whole thing.

“Shes gonna be late tonight,” he replied quietly. “Work project.”

Sarah stared at the peanut butter smear on the counter, tracing its shape with her eyes like it held some hidden answer. Billy shifted his weight, his socked foot scuffing against the linoleum. The silence stretched until Sarah exhaled sharply through her nose, almost a laugh but not quite. “You’re such a freak,” she said, but her voice lacked its usual bite. It was more curious than anything—like she’d found a strange bug under a rock and wasn’t sure whether to poke it or run.

Billy’s throat felt tight. He hadn’t expected her to call him names—that was normal—but the way she was looking at him now, like she was waiting for him to explain himself, made his stomach twist. “I just...” He scratched at his elbow, suddenly hyper-aware of the loose thread on his sleeve. “I dunno. It’s not like—it’s not like I planned it or anything.” The words tumbled out, half-formed and clumsy. He wished he could rewind the last two minutes, stuff the question back into his dumb mouth where it belonged.

Sarah licked the peanut butter off her thumb slowly, her eyes never leaving Billy’s face. The clock ticked again—four times now—before she tilted her head and said, “You’re serious?” Her voice was softer than usual, like she was testing the weight of the words in the air between them.

Billy swallowed hard. He could still taste the metallic tang of his own stupidity on his tongue. “I mean ... yeah?” It came out as a question, which made it worse. He wanted to kick himself. Why couldn’t he just shut up?

Sarah blinked again, her fingers tapping an absent rhythm against the countertop. The peanut butter smear had started to dry at the edges, forming a cracked halo around its center. She reached out, pressing a fingertip into it, watching the way it yielded under her touch. “You’re not joking,” she murmured, not quite a question. Her voice was distant, like she was talking to herself more than to Billy.

Billy’s pulse hammered in his throat. He hadn’t expected her to consider it. He’d braced for disgust, for her to storm out, for the inevitable shouting match that would follow. But this—this quiet, almost clinical curiosity—threw him harder than any reaction he’d imagined. “No,” he admitted, his voice cracking on the single syllable. He cleared his throat, tried again. “No, I’m not.”

Sarah’s fingers hesitated at the waistband of her jeans for a split second—just long enough for Billy to notice the tremor—before the button popped open with a quiet snick. The denim slid down her legs in a slow crumple, pooling around her ankles like melted wax. She kicked them off with one foot, the fabric skidding across the linoleum, then hoisted herself onto the counter with a little grunt. The peanut butter smear squished under her bare thigh as she settled, legs swinging absently, heels thumping against the cabinet doors below. “Okay,” she said, and her voice was oddly steady, “but no kissing.” A pause. “That would be weird.”

Billy’s mouth went dry. He hadn’t actually thought this far ahead. The question had been a stupid, spur-of-the-moment thing—a fantasy escaping his lips before his brain could censor it. Now Sarah was sitting there in her stupid unicorn-print underwear, knees bumping together, her socks mismatched (one striped, one plain white), looking at him like he was a math problem she wasn’t sure how to solve. The overhead light caught the flyaways in her messy ponytail, turning them into a fuzzy golden halo. Billy realized, with a jolt, that he’d never seen her this close before—not really. There was a tiny scar above her eyebrow from when she’d fallen off her bike in fourth grade.

Billy’s breath hitched when Sarah’s knees drifted apart—slow, deliberate, like she was testing the give of a new joint. Her underwear stretched tight across her hips, the fabric riding up just enough to reveal the faintest shadow of something more beneath. The overhead light caught the sweat-damp flyaways at her temples as she tilted her chin up, challenging. “Well?” she said, and Billy realized with a jolt that she was waiting for him to move first.

His hands felt like they belonged to someone else—clumsy, oversized things that hovered near his thighs before finally settling on the waistband of his jeans. The button popped open with too much force, the zipper grating loud in the quiet kitchen. Sarah watched, her gaze flickering between his face and his fumbling fingers, her expression unreadable except for the slight pinch between her eyebrows. When his jeans pooled around his ankles, she inhaled sharply through her nose but didn’t look away.

Billy’s fingers trembled as he pulled himself free from his boxers, the sudden exposure to the kitchen air making him shiver. His cock jutted out awkwardly, the tip already slick with pre-cum, and for a dizzying second he wondered if he’d pass out from the sheer unreality of this moment—his sister’s thighs bracketing his hips, the smell of peanut butter and citrus cleaner thick in his nose. He hesitated, the head of his dick brushing against the stretched fabric of her underwear, damp from her own arousal. The cotton was warm. So warm.

Sarah inhaled sharply through her nose, her fingers twitching against the counter’s edge before she reached down—slow, like she was moving through syrup—and hooked her thumb under the gusset. She didn’t look at him as she slid the fabric aside, just kept her gaze fixed somewhere past his shoulder, her lips pressed into a thin line. The exposed skin was pink and glistening, and Billy’s throat clicked when he swallowed.

Her fingers circled his wrist—her grip unexpectedly firm—and guided him downward until the tip of his cock nudged against her entrance. The heat was almost unbearable. Billy’s breath stuttered in his chest, his hips jerking forward instinctively before he caught himself. Sarah’s nails dug into his wrist, not quite painful, but enough to make him freeze. “Easy,” she murmured, and for the first time since this started, she met his eyes. Her pupils were blown wide, swallowing the blue of her irises almost completely.

Billy’s pulse hammered in his throat as she adjusted her grip, her fingers smearing pre-cum down his shaft with a clinical sort of detachment. The sensation made his knees wobble. When she repositioned him—the blunt head of his cock pressing insistently against her—he made a noise he didn’t recognize, something raw and desperate clawing its way out of his lungs. Sarah’s breath hitched in response, her thighs tensing around his hips. For a suspended moment, neither of them moved. The refrigerator hummed. A car door slammed somewhere outside.

Billy’s exhale shuddered through him as Sarah eased him forward, inch by excruciating inch. The tight, wet heat of her made his vision blur at the edges. Some distant part of his brain registered the peanut butter jar still open on the counter, the way Sarah’s toes curled against his shins, the fact that her ponytail had come half-undone—but all of that dissolved into static when she took him in with a choked little gasp of pain. Her fingers spasmed against his hips.