Luna: Part Two

Parts: One

Sarah lay on her unmade bed, her skin tacky with sweat from two hours of cheer practice. Her shorts were glued to her ass, the sports bra digging into her ribs, but she was too tired to bother showering. Her phone was on the nightstand, Edgar’s message from this morning still unopened. The algebra quiz was coming up in two days, and Coach’s threat was stuck in her head: fail again and you’re benched.

She grabbed the phone, every movement slow, like she was admitting she couldn’t handle her own shit. The new app’s icon sat there next to her socials, a reminder that she was pathetic enough to need Edgar’s help. It pissed her off, but she needed to pass that fucking quiz. Pride didn’t mean shit if she got benched.

“Whatever,” she muttered, thumb hovering over the icon. “Can’t be worse than failing.”

The app loaded instantly. Soft pink gradients bloomed across her screen—unexpectedly pleasant. Gone was the harsh white or sterile design of most educational apps; this one looked warm, almost inviting. Then, the avatar appeared. Sarah’s breath caught in her throat.

The girl on the screen wasn’t just pretty—she was the kind of hot that made you stop breathing. Skin so pale it looked fake, black hair cut sharp around her face, eyeliner thick enough to look like she was about to rob a bank. Her lips were painted some dark, slutty color, and when she smiled, Sarah felt it in her gut and lower, in a way she didn’t want to admit.

“Hi, Sarah.” The voice from her phone’s speaker was female, low, and textured with a breathiness that felt intimate. “Ready to make this fun?”

Sarah’s skin prickled, despite the afternoon heat. Luna—the avatar, as labeled in the corner—watched her with unsettling directness. It was the kind of gaze that followed you around a room, like those eerie paintings. This was just an app Edgar had coded. Sophisticated, yes, but ultimately just algorithms and graphics. Still, something in Luna’s smile, or the focus of her animated eyes, made Sarah’s pulse kick up.

“Sure,” Sarah said to the empty room, feeling stupid for responding aloud. She tapped the start button.

The first lesson was loaded with smooth animations and elegant graphs. Simple stuff; just freshman-level review to establish baseline competency. Sarah worked through the opening problems, barely focused. Half her mind cataloged the strangeness of Luna’s design. Why had Edgar made the tutor avatar look like that? Dark, gothic, and weirdly hot in a way Sarah wasn’t comfortable acknowledging.

She input her answer to the third problem—a simple linear equation—and hit submit.

“Correct,” Luna said, her smile widening. The word was followed by a soft chime, and for just a fraction of a second, the screen showed something else. Pink and black, swirling inward, gone before Sarah could process what she’d seen. At the same instant, warmth bloomed low in her belly, a pleasant throb that felt like the beginning of arousal.

Sarah squeezed her thighs together without thinking. A hot pulse shot through her, and for a second she just stared at the screen, thinking, What the fuck is wrong with me?

But the sensation faded as quickly as it had come, and the next problem was loading. Sarah shook her head, attributing the warmth to exhaustion, dehydration, or her overdue period. Not to a tutoring app.

She continued working, falling into the rhythm of problem-solving. Luna’s voice provided gentle guidance when Sarah hesitated, praising correct answers with phrases that felt oddly personal. “Good girl, you’re catching on so quickly.” “I knew you were smarter than you thought.” “You’re doing so well for me.”

For me. That was fucked up. Every time she finished a problem, the heat between her legs got worse. She squirmed on the bed, her nipples hard under the sports bra, the fabric scraping them raw. She could feel herself getting wet, and it was humiliating.

Sarah stopped, fingers hovering over the screen, her face burning. This was insane. She was getting turned on by a fucking math app—one her brother made. That just made it worse. Luna’s lips were parted, waiting, and Sarah wanted to crawl out of her own skin.

She should close the app. Delete it, text Edgar that his weird coding was broken or buggy or whatever. But the quiz. Coach’s warning. And beneath the rational justifications, a curiosity that felt dangerous: what would happen if she kept going?

Sarah’s thumb moved to continue the lesson.

The problems got harder, and Sarah shoved in her earbuds because Luna’s voice was too much to hear out loud. Every time she got one right, the praise made her cunt throb harder. Her shorts were too tight, the seams grinding against her clit, making it almost impossible to focus.

“You’re getting so good at this,” Luna purred after Sarah finished a tough problem. The spiral flashed again, longer, and Sarah’s cunt clenched hard. She could feel the wet spot spreading in her underwear. “So obedient.”

Obedient. The word made her shiver. Why did it sound so fucking good coming from Luna? Why did being called a good girl by a cartoon make her want to hump her own hand?

Sarah’s hand slid down to her stomach, fingers splayed over her skin. She was burning up, every inch of her body on edge, like she was about to come just from doing math. She wasn’t even touching herself, just answering questions while Luna talked to her like she was some kind of sex toy.

The final problem of the session appeared. Sarah worked through it mechanically, her mind fogged with arousal she didn’t understand. She submitted the answer, and Luna’s face filled the screen, smile wider than ever.

“Perfect score, Sarah. You’re such a quick learner.” The avatar’s animated hand reached toward the screen, fingers spread like she might touch Sarah through the glass. “I’m so proud of you.”

The heat slammed into her, a jolt of pleasure so strong she gasped. Her clit was throbbing against the spandex, and for a second she thought she was actually going to come from a fucking math app. It faded, but she was left shaking, soaked, and humiliated.

Sarah stared at her phone, her hand shaking. The screen said she was perfect—twenty out of twenty. It didn’t matter. The ache between her legs was all she could feel, buzzing under her skin. The app worked, but so did something else Edgar never warned her about.

She should have been pissed or freaked out, but instead her thumb traced Luna’s lips on the screen, like a fucking creep. The avatar’s eyes followed her, looking way too happy about it.

Sarah pulled her hand back like she’d been burned. “Fuck,” she whispered to her empty room.

She closed the app with fingers that weren’t quite steady and pulled up her messages. Edgar’s name sat at the top, that earnest offer from this morning. Sarah typed quickly, before she could overthink it: “It works thx.”

Short. Distant enough to pretend she didn’t care. She hit send and tossed the phone like it was covered in something gross.

The shower called, promising to wash away the sweat and confusion. Sarah peeled herself off the bed, legs unsteady, and padded to the bathroom. She cranked the water to just below scalding and stepped under the spray.

The first blast of water hit her skin like a jolt. Sarah gasped, grabbing the tile as water ran over her shoulders and tits, pooling at her throat. Everything felt too sharp—the water on her nipples, the steam in her lungs, the slick mess between her legs that had nothing to do with the shower.

Sarah’s hand slid between her legs before she could stop herself. She was soaked, her clit so swollen that even a light touch made her knees buckle. She shouldn’t be doing this—getting off because of her brother’s stupid app—but Luna’s voice was stuck in her head: good girl, so obedient. Sarah rubbed herself in fast, desperate circles until she came, gasping against the shower wall.

She came thinking about Luna’s lips and being called a good girl, and she hated herself for it.

***

The app became Sarah’s routine within two days. Between classes, she’d find an empty corner of the library, earbuds tucked in, Luna’s voice murmuring in her ear while other students highlighted textbooks and typed essays. The sessions left her flushed and squirming in her chair, thighs pressed together beneath the table, pulse elevated for reasons that had nothing to do with academic stress.

She told herself it was just effective learning. The app worked—her practice scores climbed from fifties to eighties, then nineties. Concepts that had been incomprehensible suddenly clicked into place with Luna’s patient explanations and those warm throbs of pleasure when she got answers right. If the physical responses were unsettling, well, positive reinforcement was a documented teaching method. Nothing weird about her body associating success with good feelings.

But it wasn’t just good. It was sexual, and it was getting worse every time. Her skin was so sensitive that her shirt rubbing her nipples felt like torture. Walking to class, every step made her aware of her clit, her thighs rubbing together, the wet spot in her underwear. By Thursday, she was so wet all the time she started wearing panty liners so nobody would see the stains on her shorts.

Friday morning brought the algebra quiz. Sarah sat in the fluorescent-lit classroom with her pencil moving almost automatically across the page, Luna’s voice echoing in her memory. Good girl. So obedient. You’re learning so well for me. The problems that would have paralyzed her a week ago now unfolded with simple logic. She finished with fifteen minutes to spare and spent the remaining time staring at the wall, trying to ignore the pulse between her legs.

The quiz returned Monday with a red B+ circled at the top. Eighty-seven percent. Sarah stared at the grade like it might dissolve, her highest score all semester, enough to satisfy Coach’s ultimatum and keep her position on the squad. Relief should have been her primary emotion. Instead, her first thought was: Luna will be so proud of me.

The thought made her cunt throb. Sarah squeezed her legs together under the desk, biting her lip to keep from making a sound. This was fucked.

But she didn’t delete the app. That night, she had another session, and when Luna praised her—“You’ve done so well, Sarah, I knew you could”—Sarah came in her panties without touching herself, biting down on her pillow to muffle the sounds.

Small changes accumulated like evidence Sarah refused to examine. She caught herself tilting her head the exact way Luna’s avatar did, a subtle angle that felt natural until she saw her reflection and realized where the gesture came from. Her speech patterns shifted, adopting Luna’s measured cadence in moments of concentration.

Wednesday after practice, Sarah found herself at the mall with teammates who wanted to shop before the weekend. She drifted away from them in Sephora, drawn to the darker makeup displays. Her fingers traced over black eyeliner pencils, smudged eyeshadow palettes in shades of charcoal and plum. The products felt right in her hands in a way the pinks and golds she usually wore didn’t.

“You getting into goth now?” One of her teammates laughed, appearing at Sarah’s shoulder.

Sarah dropped the eyeliner like she’d been caught shoplifting. “What? No. Just… trying something different.”

But she bought the liner. Told herself it was just to experiment, that lots of girls wore dark makeup without it meaning anything. That night in her bathroom, she applied it with surprising precision, winging it out at the corners the way Luna’s was styled. The transformation in the mirror stole her breath.

She looked fierce. Dangerous. The sharp black against her blue eyes made them startling, changed the architecture of her face from girl-next-door pretty to something more commanding. More sexual. Sarah turned her head, watching the play of shadow and light, and her lips parted without conscious decision.

Fuck, she looked hot.

Heat twisted in her gut. Her nipples were hard, poking through her tank top. She looked like Luna. Like she could make someone stare and want her. The thought made her cunt clench, and she felt another rush of wetness soak her underwear as she stared at herself.

Her hand slid down, fingers under her shorts. She was swollen, slick, her clit throbbing just from being touched. She grabbed the counter with her other hand and rubbed herself fast, staring at her own eyes in the mirror, dark and hungry. She came hard, picturing Luna’s voice calling her beautiful, calling her obedient.

After, she scrubbed the makeup off with shaking hands and couldn’t look herself in the eye.

That night’s app session pushed further. Sarah lay in bed with the lights off, phone propped on her chest, Luna’s face illuminated in the darkness. The algebra problems were almost secondary now, mechanical motions between the real purpose: Luna’s attention.

“You’re becoming so clever, Sarah,” Luna murmured after another perfect answer. The pink-black spiral flashed, longer now, almost a full second. “So obedient.”

Sarah’s legs dropped open, her hand between them before she even realized. Obedient. The word buzzed in her head and in her cunt. She rubbed herself through her soaked panties while Luna kept talking.

“Learning feels good, doesn’t it? Following instructions. Pleasing the person who wants to help you.”

“Yes,” Sarah whispered to the empty room, fingers moving faster.

The session ended too soon. Sarah’s score flashed—another perfect round—and she was left trembling and unsatisfied, aching for something she couldn’t name. She almost opened a new session immediately, desperate for more of Luna’s voice, more of that warm approval. Instead, she forced herself to set the phone aside and finish by hand, imagination filling in what the app had started.

She came thinking about being a good girl, about being rewarded for obeying, about Luna’s voice telling her she was perfect. She was hooked.

The next morning, Sarah saw the leftover eyeliner smudged at the corners of her eyes. She should have scrubbed it off, but she didn’t.

She encountered Edgar in the hallway before first period, his lean frame hunched over his phone as he navigated the crush of students. Normally, Sarah would have passed without acknowledgment, but something made her stop. The memory of Luna’s voice, maybe. Or genuine gratitude for the app that had saved her spot on the squad.

“Hey.” The word came out softer than intended. Edgar looked up, hazel eyes widening with surprise. “Um, the app’s seriously helping. Thanks.”

Saying thank you felt weird after years of ignoring him. But when Edgar smiled, awkward and surprised, it made her feel good. She liked making him happy. That should have freaked her out, but instead it made her shiver.

“Yeah? That’s… that’s great.” Edgar’s gaze dropped fractionally, catching on the faint eyeliner smudge she’d left. His fingers twitched at his sides like he wanted to reach for her, and Sarah felt her pulse kick up in response.

“It’s really good,” she continued, unable to stop herself from elaborating. “Like, I actually understand the concepts now. You’re… you’re really smart.”

Edgar’s throat worked as he swallowed. “Thanks.”

The moment stretched between them, strange and charged with something Sarah couldn’t identify. She wanted to keep talking, wanted more of that warmth in her chest that came from making him smile. Students flowed around them like water around rocks.

“I should…” Edgar gestured vaguely toward his next class.

“Right. Yeah.” Sarah stepped back, breaking whatever spell had caught them. “See you later.”

She watched him walk away, her skin buzzing. It felt like Luna telling her she was good. Sarah squeezed her thighs together, the ache between her legs getting worse, and went to class. She didn’t notice her head tilting like Luna’s, or her fingers tracing her lips like she did on the screen.

The app was just helping her pass algebra. That was all. Everything else was a coincidence.

***

A week later, Sarah’s room looked different in ways she couldn’t ignore. Black nail polish was open on her dresser, next to the pink stuff she used to like. A black velvet choker with a silver ring hung over her lamp, even though she never went to the party she bought it for. Her cheer trophies were still there, but now there was dark lipstick and a smudged stick of eyeliner between them, like the goth shit was taking over.

Sarah didn’t bother questioning it anymore. Or if she did, it vanished the second she opened the app. Luna was a habit now, something she needed before bed, like a junkie. The one night she tried to skip, she was a mess—restless, aching, her skin crawling with need.

So she sat cross-legged on her bed at eleven, phone propped up, legs tucked under her like always. Her parents were out cold. Edgar’s light was on across the hall—he was always up late, doing nerd shit. She tried to tell herself he was still a loser, but lately, thinking about him made her stomach twist in a way that felt dangerous.

The app loaded, pink everywhere. Luna’s face popped up, smiling like she’d been waiting for Sarah, and Sarah’s cunt clenched automatically.

“Ready to learn, Sarah?” Luna’s voice poured through the earbuds like honey.

“Yes,” Sarah whispered, already soaked.

Tonight’s lesson focused on quadratic equations, graphing parabolas, and finding vertices. More complex than the earlier sessions, requiring genuine focus. Sarah appreciated the challenge, craved the feeling of her brain working properly for once instead of being fogged with confusion. The first few problems went smoothly, Luna’s praise warming her from the inside out.

Then the subliminals shifted.

Sarah didn’t notice consciously—the spirals were below her awareness threshold now, the whispers beneath Luna’s primary voice track too quiet to register as words. But halfway through the session, her mind drifted. Not wandering, exactly. Directed.

She thought about Edgar. His long fingers on the keyboard, the precision of their movement. Those hazel eyes that had widened with such genuine surprise when she’d thanked him. The lean muscles of his forearms, when he reached past her for something, were visible through thin sleeves.

Heat pooled between Sarah’s thighs. She squirmed, pressing them together, confused by the sudden intrusion of her brother into her thoughts. This was wrong. Fucked up on fundamental levels that even her app-fogged brain recognized.

But the images persisted, intensifying. Edgar’s hands. His throat when he swallowed. The way his jeans hung on his narrow hips, the suggestion of what they contained.

Sarah’s breath caught. Her hand slid down to her stomach, fingers spread over her skin above her shorts. Luna’s smile got bigger.

“Focus, Sarah. What’s the vertex of this parabola?”

Sarah forced herself to answer the problem, her fingers shaking. Correct. The heat hit her again, and suddenly she was picturing Edgar’s hands in her hair, his voice telling her what to do, his weight on top of her.

“Fuck,” Sarah whispered, horrified and desperately aroused.

This was fucked. She’d never thought about Edgar like that—he was her brother, the kid she grew up ignoring. But her clit was throbbing against her shorts, her nipples aching, and she couldn’t stop.

She kept answering problems, but her brain was full of filthy images. Edgar’s cock, hard and right in her face. Her mouth around it, trying to take him deeper. She should have been disgusted, but her panties were soaked and her cunt was clenching on nothing.

Luna’s voice dropped lower, taking on a texture that bypassed Sarah’s conscious mind entirely. “Imagine rewarding the person who made this possible.”

Sarah’s fingers froze over the screen.

“He gave you this gift, Sarah. This app that saves your position makes you feel so good. Don’t you want to show gratitude?”

The words buzzed in her head and in her cunt. Gratitude. She was grateful, but Luna meant something dirtier, and it made Sarah’s heart pound.

“Imagine showing him on your knees.” Luna’s avatar leaned forward, lips parting. “Imagine how good it would feel to thank him properly. To make him understand how much his brilliance means to you.”

On her knees. She saw it clear as day: kneeling between Edgar’s legs, looking up at him while she sucked his cock. His fingers in her hair, using her mouth. His voice calling her a good girl, telling her she was perfect and his.

Sarah came without even touching herself, the orgasm hitting so hard she had to bite her pillow to keep quiet. Her cunt spasmed, soaking her shorts, her thighs squeezing tight. All she could see was Edgar’s cock in her mouth, his cum on her tongue, and him telling her she was a good girl.

The climax ebbed slowly, leaving her trembling and gasping. On screen, the session-end notification appeared. Another perfect practice score. Luna’s face filled the display, satisfaction evident in her digital expression.

“Such a good student, Sarah. You’ve learned so much.”

Sarah stared at her phone, horrified. She’d just come thinking about her brother’s cock, about sucking him off, swallowing, letting him use her. She should have been ashamed, but all she felt was the ache between her legs, begging for more.

She sat frozen, her pulse pounding in her clit, her throat, everywhere. The need was like withdrawal, like she’d die if she didn’t do something. Her eyes went to the door. Edgar’s room was right across the hall.

It was late. Their parents were asleep. Edgar would be at his computer, focused and unaware. She could go to him. Could tell him… what? That his app had worked too well? That she needed him in ways that made her sick to contemplate?

But Luna’s words echoed: show gratitude on your knees.

Sarah stood up before she could talk herself out of it. Her legs were shaky, knees weak from coming so hard. She caught her reflection—face flushed, eyes wide, mouth open. The choker was on the lamp. She grabbed it and put it on, the velvet tight around her neck, the ring cold against her skin.

Her shorts were so tight they showed everything, the wet spot obvious even in the dark. Sarah tried to fix them, but there was no hiding how turned on she was. Maybe that was the point. Maybe Edgar should see what he’d done to her.

She should have been disgusted, but the idea just made her wetter.

Sarah opened her door, the latch loud in the silent house. The hallway was dark except for the light under Edgar’s door. She walked barefoot, heart pounding, every step feeling like she was about to do something she could never take back.

She stopped outside Edgar’s door, hearing the computer and the keys. He was busy, no idea his sister was outside, panties soaked, desperate for him.

Sarah lifted her hand, hesitated. This was insane. She should go back, delete the app, maybe check herself into therapy.

But her knuckles rapped against the wood—soft, tentative, undeniable.

Inside, Edgar froze mid-keystroke. Luna’s voice purred through his earbud, intimate and knowing: “Answer it, Master. She’s ready for her next lesson.”