Mary had been squirming in her seat for the entire drive home. As soon as she’d sat down in the car Mary had found herself zoning out to the perverted day dreams; they just wouldn’t leave her alone. It felt like they never ended as every minute Mary would have another fantasy pop into her head of herself acting like a shameless slut for her boyfriend, or making out with her sister, or letting Ruth and Paul torment her with all sorts of wonderful sex toys, or kneeling on the floor as Paul fucked Ruth in front of her.
    It was horrible, and Mary was shaking with anger.
    It was wonderful, and Mary was shivering with need.
    It was indescribably hot, and Mary wanted to fuck herself badly.
    She had already fucked herself back in the restaurant bathroom and the shame was something that Mary couldn’t shake. Why was she having fantasies about her own sister? Mary felt like she was going crazy, but that didn’t stop her from being so impossibly wet.
    They were nearly halfway home when Mary finally snapped out of her daze and felt the tension in the car. Paul was gripping the steering wheel tight, his jaw set. Mary instantly felt the need to suck his cock and help him relax. She knew it was wrong and something that a slut would do, but it was her first instinct, and a compelling one too.
    Mary glanced into the backseat and saw Ruth lounging comfortably in the middle seat, her arms resting behind the headrest on either side of her. She resembled a queen leisurely sitting on her throne, a smug smile set on her face as she stared out the window. Ruth had one leg crossed over the other, and Mary realized to her shock that she was able to see her sister’s pussy beneath her dress.
    Mary wanted to look away, but she couldn’t bring herself to stop staring. It was these weird thoughts in her head. It had to be. Why was she thinking about fucking and serving her twin sister? A sister she loathed normally. Her and Ruth had always fought, which only made it all the more confusing that Mary had eaten her out back in the restaurant.
    Mary’s heart skipped a beat. Oh god, she had gone down on her sister. Mary had told herself it was nothing but another one of those dirty fantasies in her head, and yet it was too vivid to be fake. As Mary stared at her sister’s pussy she licked her own lips and remembered Ruth’s sweet taste.
    What the hell was happening to her?
    Then she heard the last sound Mary wanted to hear: her sister’s annoying, cocky chuckle.
    Shivering with shame, Mary lifted her gaze and saw Ruth watching her, that insufferable grin plastered on her face. So she’d left her legs open on purpose, as a trap. Ruth wanted Mary to see her wet cunt. She knew that Mary would stare and want to taste her again, that it would set off fantasies of wanting more…
    No, no, that couldn’t be right. Ruth couldn’t have known Mary would want that because there was no way that Mary actually wanted any of that. She didn’t want to fuck her twin sister, no matter what the persistent day dreams kept telling her.
    And yet here she was, with Ruth catching her staring at her cunt.
    Ruth chuckled again and opened her legs a little wider. “See anything you like?”
    “No,” Mary squeaked as she hurriedly sat back down into her seat. She discovered as she sat down that she was unbelievably wet. So wet that Mary worried she’d leave a stain in her dress. Then everyone would see what a horny slut she was.
    She glanced over at Paul, hoping to explain that she really wasn’t looking at her sister’s cunt, that it was a mistake, but he still wore that strained expression, eyes fixed on the road as he drove. Considering the way she acted back at the restaurant, Mary couldn’t blame him for being mad with her.
    She was just so horny, and she kept picturing Paul fucking Ruth madly in her head and it was driving her crazy!
    “What’s wrong?” Ruth asked from the backseat. “Are you upset that you didn’t get to eat at the restaurant?”
    Mary glanced down at the to go boxes stacked at her feet.
    “Yup, that’s it,” she lied urgently. “I’m just really…” She gulped. “Hungry.”
    “It’s your own fault then.” Ruth gave one of her patented smug laughs. “We would have been able to eat there if you could stop yourself from being such a slut and blowing your boyfriend under the table.”
    Mary blushed bright red as the memory flooded in. There was the taste of Paul’s cock, mingling with the sweeter taste of Ruth’s pussy. The two of their tastes combined made Mary squirm, picturing Paul bending Ruth over to fuck her. And after he’d cum inside her twin sister, Paul would make Mary lick his cock clean, tasting both of them while Ruth laughed. 
    “I’m sorry,” Mary muttered, kicking the horrible- wonderful- thought away. 
    “You even got so horny that you ate me out,” Ruth said with mock scandal in her voice. “You’re own sister, too.”
    “That’s not my fault!” Mary cried as she spun around in her seat to face Ruth. “I didn’t have a choice. I had to eat you out because… because…”
    “Because why?” Ruth smirked, and Mary bit her lip, at a loss for what to say. 
    Beside her, Paul grimaced, and Mary wondered what he must think of her. That she would just suck his cock in public like that was shameful enough. In the back of her mind, though, came the faint memory of having done that before, though Mary couldn’t be certain if that was real or just another fantasy of hers. Still, blowing Paul in public was one thing, but to go down on her sister?
    At least she had an excuse for this, as shameful as it was. “I had to eat you out so that I could suck Paul’s cock more.”
    Ruth raised an eyebrow. “Are you serious?”
    “Yes,” Mary said, wondering what Ruth was talking about. “You’re the one who told me that I couldn’t.”
    “I’d never say anything crazy like that.” Ruth was looking at her like she was mad.
    “But… you did. You said… something, and then I couldn’t get my mouth around Paul’s cock anymore and so you made me eat you out.”
    “I wasn’t grabbing you or holding you back or anything. If you want to be a slut I’m not going to stop you, sis.”
    Mary pounded a fist on the side of the seat. Why the hell didn’t Ruth remember? She was there too! “I couldn’t put Paul’s dick in my mouth, I swear! It was like there was a-” She faltered, blushing. “A forcefield or something.”
    Ruth snickered. “Did you just say a forcefield?”
    Mary collapsed back into her seat as Ruth’s bellowing laughter made her feel ridiculous. She saw Ruth kick the back of Paul’s seat.
    “Hey Paul, does your cock really have a forcefield?”
    Paul finally looked over to Mary, offering her an apologetic smile. “I- no, it doesn’t.”
    Mary’s heart fell. But it had really happened. Mary knew it had! She was unbelievably horny and taking his cock as deep into her throat as she could, and then all at once she felt some weird force just push her back. And every time she’d tried to take his dick again there was some invisible pressure that kept her away.
    Except, now that she thought of it, wasn’t that impossible? Mary knew it was real, the humiliating memory clear in her head, but that kind of stuff just wasn’t possible. And Paul was acting like it hadn’t happened either. Like she hadn’t been whimpering under the table as she tried and failed to suck his dick. Did he not remember? Or did it… did it really not happen?
    Mary gripped the hem of her dress as terrible doubt crept in. Because if that wasn’t real, if there actually wasn’t something stopping her from sucking Paul’s cock, then why had she eaten out Ruth? There must have been a good reason for her to do something as wrong as commit incest, right?
    Dirty images flooded her mind. Of her eating out Ruth more, loving it like she was addicted to her sister’s cunt. Images of her on her back as Ruth ate her out, loving the feel of her sister’s tongue against her clit. Images of her and Ruth kissing, groping, fucking. All of it flew through her head so fast that Mary could no longer tell which of them was herself and which was Ruth. All she saw were two beautiful, identical women passionately making love.
    And the sight of it made Mary want to cum so badly.
    What the fuck was wrong with her?
    A comforting hand rested on her shoulder, and Mary was pulled out of the perverse dream. She gave a sigh of relief and reached up to hold Paul’s hand, except when she laid her hand down she found the fingers too thin and feminine.
    Mary whirled to see Ruth holding her shoulder and offering a comforting smile. “Hey, it’s okay. We all get cravings for pussy sometime.”
    “Shut up.” She looked away, but Ruth kept her hand on Mary’s shoulder.
    “I mean it. You don’t know how many times I’ve seen a hot girl and wanted to just eat her out, but you really just went for it. I’m kinda proud of you.”
    “Proud that I ate out my slut of a sister?” Mary snapped.
    She expected Ruth to get pissed and insult her back. It was their usual pattern, after all. She calls Ruth a slut and Ruth calls her a prude and they hate each other.
    But this time, Ruth kept squeezing her shoulder reassuringly. When she spoke her voice was even. “Honestly, yes. You didn’t care about dumb rules or anything like that. You just did it. I’ve dreamt about going down on you for years and was too afraid to do it.”
    Mary looked at her in shock. Her sister was always making crude jokes like that, but now, after Mary had actually eaten her out, it was too real to joke about. Except Ruth didn’t seem to be joking. She looked serious. 
    “I mean it. I’m proud of you.” Ruth broke into a grin. “And hey, if you want me to return the favor, I’d be more than happy to go down on you.”
    Mary opened up her mouth to turn her down-
    And instantly saw a vivid flash of herself naked, while Ruth had her head buried between her legs. Ruth’s tongue was working inside of her cunt, feeling so real as it hit every perfect point. And there was Paul, naked and muscles gleaming  as he fucked Ruth from behind. He was fucking her with abandon, and every time he shoved his cock into Ruth, Mary could feel the force of it pass through into her. Ruth was moaning into Mary’s cunt, and Mary wanted to cum more than anything. To watch Paul cum inside her sister. And then to crawl beneath Ruth and lovingly eat her out, to lick Paul’s cum out of her snatch and taste her boyfriend and her sister at the same time.
    -and quickly shut her mouth, blushing furiously.
    Ruth giggled. There was a knowing gleam in her eyes, a dangerous look, as if she’d seen the fantasy in Mary’s head.
    “My offer stands, so think about it.”
    “I don’t need to think about it. I’m not interested.”
    “Ohhh, I get it. You’re still desperate for Paul’s cock, aren’t you?”
    A guilty shiver ripped through Mary. Her mouth watered just at the mention of her boyfriend’s dick. Before she could stop herself her eyes stole over to Paul’s lap. And to her shock saw the outline of his erection.
    Mary whimpered. What was wrong with her? It felt like she was an addict who needed another fix.
    “Does Cockhungry Mary want her boyfriend’s cock?”
    She would have yelled at her sister for such a crude nickname- and she had a vague memory that Ruth had called her that earlier too- except a sudden flash of need went off in Mary’s mind like an atomic bomb detonating. Her cunt gushed, her heart raced, and her thoughts were scattered against the all consuming desire to have Paul inside her mouth, as soon as possible.
    When Mary came back to her senses she noticed they were stopped at a red light on some dark wooded road. Paul was giving her a concerned look and Mary desperately hoped that she hadn’t made any weird noises while she’d been overcome with… whatever that had been. She just needed his dick so bad. His amazing cock going deep down her throat. Mary felt herself losing focus and forced herself to snap back to reality.
    “Mary, are you okay?” Paul asked.
    “I-”
    “She’s fine,” Ruth cut in. “My horny slut of a sister just wants to give you a blowjob. Ain’t that right, Mary?”
    Mary felt herself go bright red, but for some reason she couldn’t deny it. “Yes,” she said quietly, clit throbbing with need.
    “You didn’t get enough of him at the restaurant, did you?”
    “No,” Mary whimpered. She was so wet, unbelievably wet. It felt like she was sitting in a puddle of her own shameful need.
    Ruth cackled happily in the back seat and said, “Then you better help her out, Paul.”
    Mary glanced over at her boyfriend. She wanted to apologize for how crude her sister was. Or beg Paul to let her suck his cock like she was the eager slut that Ruth made her out to be. She didn’t know which was the right thing to say.
    She saw Paul smile uneasily, as if something were weighing on his conscience. “I’ll take care of you when we get home.”
    Mary’s heart soared. Just the thought that in a few minutes she’d be sucking cock was enough to make her ready to cum with joy. It was humiliating for her to have Ruth hear that, since she’d no doubt use it against her, but for some reason Ruth sounded bitter.
    “That’s no fun at all. Let her suck your cock now so I can watch.”
    Both Mary and Paul looked back at Ruth with shock. “We can’t just do that in the open,” Paul scolded her. Honestly Mary was amazed that he was being this patient with Ruth’s ridiculous behavior tonight. Paul really did love her to put up with her sister like this.
    “That’s right. No matter how hot it would be… and it’d be really hot to just… start sucking him off…” Mary trailed off, then sat up straight, face flushed. “But not if people are going to see me!”
    For some reason that thought gave Mary the strength to resist her desires. Right now she was burning up with her need to have Paul fucking her face. It was nearly consuming her, and yet it seemed to be manageable when Mary remembered that other drivers on the road might see her. So surely that same reasoning would be enough to stop Ruth, too.
    Except Ruth had a wide, trouble-making grin on her face. She waved a hand out to the night outside the windows. “I don’t see any other drivers around.”
    That burning spike of need seemed to twist inside her, and Mary found herself instantly whirling around to look in all directions. Sure enough the intersection was completely empty. There wasn’t even a hint of headlights from another driver around. They were entirely alone.
    Just her and Paul.
    And Ruth, but Ruth was fine. Ruth could watch her suck cock. Ruth had every right to watch her suck Paul’s cock.
    Some shrill voice of sanity tried to explain to Mary that all of this seemed so wrong, but that voice was quickly drowned out by the wave of pure, steaming lust that flooded Mary’s mind. Her resistance gave up a few faint bubbles, staying Mary long enough to hesitate for a few seconds.
    “Mary,” Paul said in a reassuring tone. “You can wait until we get home. You don’t have to do this.”
    Then, barely louder than a whisper, she heard Ruth mutter, “Cockhungry Mary.”
    Everything went white. Or red. Or pink. Or some kind of pretty color. It was hard for Mary to focus.
    All she knew was that some blinding force hit her head and it was hard to think. When she paid attention to what she was doing Mary was shocked to find her head in Paul’s lap, his hands ripping at the fly of his pants while he tried to push her away.
    “Mary, stop!”
    Her searching fingers froze.
    “Keep going!” Ruth cheered, and Mary was back in motion, ripping at his pants and finally getting the fly down.
    “Mary, you have to- mmfpph!”
    The word was a muffled cry that Mary couldn’t figure out. She had a hand reaching into his pants, and she knew she was so close to that wonderful cock she needed, but Mary still felt concerned. She fought the all-consuming need for cock and looked up. To her shock Paul was trapped against the car seat, with Ruth’s arms wrapped around him to pin him there. Ruth had one hand clapped over his mouth, and a dangerous smirk on her face.
    “Shut up,” she hissed to Paul. Then she grinned down at her sister. “Keep going. Suck his cock for me, Mary.”
    Fuck, that sounded wonderful. Mary had never wanted anything more in her life. Still, no other woman should be touching her boyfriend, even if it was to help Mary suck his cock.
    “Let him go,” Mary said weakly. She wondered why she sounded so distracted, so pathetic. It was like she couldn’t find it in her to yell at her sister. Like she needed to show her respect. As Mary dealt with that strange feeling her hand was already moving, digging deeper into Paul’s pants.
    “Paul’s fine. He’s just nervous, is all, so I’m helping him out. After all, why wouldn’t he want to have his hot girlfriend going down on him.”
    “Mmfph, mrrn mmumph!” he yelled into Ruth’s hand.
    Ruth turned to him, frowning. “Just be a good boyfriend and let Mary suck your cock.” Then she gave him a strange, meaningful look. “Or I’ll spill the beans all about your secret.”
    At that Paul tensed up, but he stopped fighting. He put his hands down to his sides and stopped trying to push Mary away from his crotch. What the hell was that? Was… was Ruth doing something to Paul?
    “What secret?” Mary asked in a concerned voice. “Paul, is Ruth making you do something?”
    Ruth’s hand was still clapped over his mouth but she saw the fear in his eyes. Oh god, he really was being blackmailed. Had Ruth found some kind of embarrassing secret of his? Mary shivered. Had he slept with Ruth?
    The thought would have made Mary furious, but it was right then that her probing hand finally found his cock. She gripped it tight and felt an electric thrill run through her.
    His cock was so warm. Pulsing with need. The same need inside her body that was driving her wild. His cock needed to be deep inside her throat. She needed to help Paul’s cock.
    But first she needed to help Paul if he was in trouble.
    “I don’t care what it is,” Mary said in a trembling voice. Holding Paul’s hard cock made it so difficult to think straight. She pushed through as best she could. “Just… let me help you. We can do something about this. You don’t have to-”
    “Cockhungry Mary,” Ruth yelled. She looked scared as she said it, but Mary lost that as another atomic burst of carnal need and bright colors flashed through her head. Paul seemed to fight above her, except Ruth was still yelling over and over again, “Cockhungry Mary, Cockhungry Mary, Cockhungry Mary, Cockhungry Mary!”
    Mary wanted to stay and fight. She truly did.
    But the sudden rush of pleasure felt like it transported her to another dimension. A world that existed of nothing but lust and passion and obedience and cock sucking. Mary was lost in it. Or had found herself in this place. As if she’d finally had the epiphany that she existed only to worship Paul’s cock.
    By the time she came to she was vaguely aware of Ruth and Paul yelling somewhere above her. She would have listened, but Paul’s cock was finally in her mouth and she latched onto it with renewed purpose. Her head started bobbing in a quick rhythm, her tongue lavishing his dick as if it were the greatest taste in the world. Which it was. There was nothing greater than sucking Paul’s cock. She loved nothing more than to suck Paul’s cock. She existed to serve Paul’s cock. Everything else was unimportant background noise.
    “Are you trying to make me crash the fucking car?” Paul shouted, not that Mary cared.
    “Hey, I didn’t think she’d just swan dive into your lap like that,” Ruth shouted back. Mary just kept sucking happily. She didn’t care when Ruth started laughing and said, “That was pretty hilarious though. You should have seen the look on your face.”
    “The look of someone about to drive off the road because his girlfriend just ripped his pants down?”
    “You managed to pull over in time.”
    “Look, I’ve about had it with you- fuck!” Paul gasped, groaning as Mary took his cock down to the base. She’d tuned out the entire argument, but the second she heard pleasure in Paul’s voice Mary instantly shivered in delight and redoubled her efforts.
    “Damn, look at her go.”
    Mary kept her focus on Paul’s cock. It was the only thing that truly mattered in her life. So she was hardly concerned when she heard Ruth reaching over the seat and lifting up her dress. It didn’t even matter to her when she felt Ruth’s fingers slip into her wet cunt. Ruth could do anything she wanted to her body, Mary decided with hardly a care. As long as nothing stopped her from worshipping Paul’s cock and giving him the greatest blowjob possible.
    And as she kept bobbing her head up and down in a rapid pace it was clear that Paul was having trouble controlling himself.
    “Stop that,” Paul suddenly shouted, and for one terrifying moment she thought that he was going to make her stop sucking his dick. Then Ruth’s probing fingers were pulled out of her pussy and she heard Ruth hiss with disappointment. Ecstatic that she could keep working Mary took Paul’s cock as deep as she could and hummed happily, hoping that he could feel the vibrations.
    “Why do you care if I finger my sister? She’s clearly fine with it.”
    “You practically knocked her into a trance using her trigger that much.”
    ‘A trance?’ Mary thought absently. She hummed with delight. Yes, being entranced by Paul’s cock would be great. To have no thoughts, just hypnotized devotion to his amazing dick. Mary kissed at his shaft, wishing that Paul could actually hypnotize her like that. It sounded wonderful for some reason.
    “I don’t get how you’re complaining right now. You get to have what looks like a stellar blowjob and I don’t spill your secret to Mary. How is this not a win for you?”
    “Because you’re going to trick Mary into fucking you,” Paul spat, which only made Ruth laugh.
    “Didn’t you say that your hypnosis couldn’t make someone do something they didn’t want? If my sister ends up fucking me, it means she’s fine with it. Isn’t that how you justify using her as your sex slave?”
    Paul didn’t reply to that, which was good. Mary was thankful for some peace and quiet so she could enjoy her cock sucking. Then Ruth had to go and ruin it by talking again.
    “You’ve got two choices, Paul. Either you sit there and enjoy this blowjob, or I’ll wake Mary up and tell her everything.”
    Mary’s cock-starved brain couldn’t follow most of what they were saying, but she did understand the desire for Paul to enjoy the blowjob. It pained her deeply as Mary forced herself to pop her wet mouth off of Paul’s cock. She gasped for breath, her chin slick with drool as she glanced up at them.
    Paul and Ruth both froze, staring at her as if they were surprised she was there. With her mind already crying out to get back to her boyfriend’s cock, Mary steeled herself and said, “I wanna please you, Paul. Please enjoy my cock sucking. I was made to suck your cock.”
    Paul just blinked at her in disbelief. Mary wanted to say more to convince him to enjoy himself, but she’d reached her limit. Mary turned back to Paul’s lap and, to her relief, took Paul’s cock back into her mouth. She made a relieved sound, feeling like a deep sea diver finally coming back up for a lungful of air.
    She felt a hand suddenly land on top of her head. Mary stiffened, praying that she wasn’t about to be pulled away until she was able to make Paul cum. Thankfully, the hand didn’t stop her, but instead began to lovingly pet her head.
    “Alright, Mary. You can keep going if that’s what you need.”
    Mary cried out a muffled sound of joy around his dick. She began to use her tongue with even more dedication, pulling out every technique and motion that she knew Paul loved. She’d do anything to repay him for giving in to her selfish desire to suck his cock.
    Somewhere farther away Mary heard clapping. “Finally,” Ruth said, exaggerating the word. “I hope my sister doesn’t have to beg that much all the time so she can get some dick from you. Then again you’d probably get off on her begging for it.”
    “Can you just stop?” Paul snapped. “The sooner I cum the sooner we can go.”
    “Touchy. But fine. It’s not like I’m getting anything out of this anyway. I mean, there’s some novel enjoyment about getting to sit back her flicking the bean while Mary sucks your cock like she’s addicted to it, but there’s so much more fun we can have when we get home. Isn’t that right, Paul?”
    Mary felt Paul’s cock throb in her mouth, and she greedily began to lick along the shaft, hoping it was a sign that Paul was enjoying himself.
    “Let me just… throw on some music and relax.” Paul shifted in his seat, reaching over Mary and trapping her head there. Not that she minded at all. She loved the idea of being trapped with his rigid cock in her mouth. To always be made to serve and please him.
    The radio suddenly came to life. It was playing some random commercial for roofing, so Mary tuned it out as she did everything that wasn’t Paul’s cock. Then the station changed and a soft melody started to play. It was a techno-style song with lots of synth and a steady, pulsing bass beat.
    Mary grinned around Paul’s cock as she instantly recognized the tune. It was one of her favorites. Paul played it for her all the time when he drove her around. It was so beautiful and relaxing. Even now Mary felt her body going limp as the simple, relaxing beat took her. Her tongue slowed, feeling drugged, and despite her enthusiasm Mary found it hard to focus on his cock anymore. She opted for a slower pace, bobbing her head in time with the pulsing bass notes that vibrated through the car’s speakers.
    Her eyes glazed over and she smiled blankly. Her head nearly stopped moving completely, but then Paul’s hands took hold of her hair and started to shove it up and down on his cock. Mary murmured a grateful sound. She lived to suck his cock, except the music was so relaxing that she couldn’t help it. But Paul didn’t need Mary awake. He wanted Mary to be obedient and deep in trance. And he could still use her mouth without her needing to think. It was so perfect like this.
    Mary heard a deep, sensual moan from the backseat, and found herself grinning wider. It was rare to have a thought pop into her head when the wonderful music was playing, but this one came through loud and clear.
    ‘I’m sure Ruth will love this song, too’ Mary thought happily, before she sank completely into trance and allowed Paul to keep fucking her mouth to his content.