The Book of Lilith
Copyright© 2025 by Igor Blackfire
Chapter 4
Incest Sex Story: Chapter 4 - Lilith Ripinski is a 15-year-old loner, with an annoying 17-year-old brother named Samuel. One day, he pushes her just a little bit too far, and they enter into an intense, surreptitious sexual relationship. "The Book of Lilith" chronicles the development of their incestuous dynamic, their struggle to keep it secret, and the way Lilith's confidence grows as a result of feeling desired for the first time.
Caution: This Incest Sex Story contains strong sexual content, including mt/ft mt ft Teenagers Consensual Reluctant Heterosexual True Story School Incest Brother Sister DomSub Rough First Facial Masturbation Oral Sex Spitting Public Sex Small Breasts Slow
She’d forgotten how good it felt to wake up in her brother’s arms. For the first ten years of Lilith’s life, all days had started like that ... a little weird, maybe, but innocent enough that their stepmother had never put a stop to it. It made sense; Annette probably figured these kids could get warmth from wherever they wanted as long as it wasn’t from her.
The two of them shared a bed right up until the day Sammy, suddenly embarrassed about his morning boners, banished ten-year-old Lilly from his room. She’d tried to reassure him that she thought it was neat, but that just made it worse; in his shame and projection, Samuel made her out to be some kind of pervert for not being grossed out.
And when it became clear he wouldn’t budge, Lilith, silent and seething, snuck into his room and broke his Nintendo 3DS and then refused to speak to him for weeks.
That’s when he started calling her ‘freak’, and it marked the start of a more depressing era in Lilith’s life—learning to sleep without Sammy had been difficult for her. She vividly remembered how no pillow could replace his simple presence, and suddenly sleeping felt uncomfortable, like she had a big hole in her chest ... So instead, she stayed up late every night, till 3:30 A.M. reading incest smut on her phone till her eyes wouldn’t stay open.
Permanent insomnia, a burgeoning porn addiction, yeah, the quality of her sleep degraded, and so did her performance in middle school. And then a year later, Emmie’s terror campaign started.
... But! Now, at age fifteen, the depression era was coming to an end! After recent events—i.e. her brother sodomizing her drunk ass in a tent out in the Adirondacks—she figured there wasn’t really a valid argument for him to keep her out of his bed any longer! After all, you could make a compelling argument that his morning wood now lay firmly within Lilith’s domain. So when she’d showed up, the Monday night after that momentous camping trip, pillow under her arm wearing nothing but a t-shirt, Samuel hadn’t protested at all, just rolled over and made room for her, restoring balance to the universe in the process.
All in all, life was looking up for Lilith Ripinski and it was all because of the big Incest. Fooling around with her brother was doing wonders for Lilith’s self-esteem; in the span of one month, she went from a total virgin to someone who’d thoroughly conquered her gag reflex, and she had a kind of secret boyfriend (though she wasn’t allowed to call him that) in the form of her big brother. Every night they’d make out for hours and get each other off via hand and mouth stuff. (Lilith’s V-card was still untouched, but in her opinion, not long for this world.)
She felt giddy all the time about it, like a new person, almost. The bullying at school barely reached her because she had this awesome, unhinged, obscene secret, her illegal sex life, a big secret, kept between her and Samuel that felt like they were playing the greatest prank ever on the whole world. Like secret agents of incest.
They were doing the nasty, and nobody could stop them. It was the ultimate fuck you to society.
At home, they barely had to bother with opsec. Annette Davis did not care what her stepchildren got up to, and in fact, she was usually zonked out on Ambien and/or melatonin gummies by 7 P.M. leaving the house to the kids. That’s how Sammy got away with smoking weed in his room all the time without a care in the world, and got to stay out till 3 A.M. on school nights, and also how he got to molest his little sister to her heart’s content.
This particular morning, by the time Sam stirred from last night’s weed-coma, Lilith was already slowly, shamelessly, grinding on him, lying on top of him kissing his neck with love, her underwear drenched for him.
It said a lot about the state of their relationship that when he woke up to this, Sam didn’t go ‘what the fuck’, but instead wrapped his arms around her and pulled her tight, took a deep whiff of her hair, then grabbed and squeezed her butt cheeks.
She kissed his nose. “Mornin’,” she went. “Wanna...?”
Morning Sam was a different Sam who didn’t feel the need to subject her to a whole little humiliation ritual about what a weirdo freaky incest slut she was etc. Morning Sam didn’t need to be cajoled into anything, Morning Sam just nodded with a big shit-eating grin on his face. Lilith grinned right back, then she dove beneath the covers to free his cock and give it an enthusiastic lick.
“Fuckin’ cumslut,” her brother said fondly.
“Mhm.” She took him in her mouth.
In the weeks since spring break, Lilith had applied herself to the task of learning how to please him. It was important to her to be a good slut, his perfect slut—not even just for submissive reasons, but because of a much darker cocktail of jealousy and pride and lust. First of all, she wanted to get so good at giving him head that he wouldn’t need other girls anymore. Second of all, it went against Lilith’s personal principles to half-ass something she spent that many hours doing.
“Mmlilly,” Sam groaned above her, “oh shit, you’ve gotten so fuckin’ good at that.”
Frankly, blowjobs had fascinated Lilith from an early age. Probably a bit too early. Unfettered internet access since the age of five in the era of PornHub was to blame for that fixation, most likely.
So she took to the task voraciously every time; bobbing her head, humming contentedly, trying different kinds of suction, tongue-work, using her hands ... learning how to decode Sam’s taciturn grunting.
If it wasn’t for the jaw and throat ache, she would describe sucking cock as ‘relaxing’. It had a definite hypnotic quality to it. Especially with how deep she could take him, it basically tickled on the same autistic brain-string as those Satisfying Sand Videos and ASMR Tiktoks and stuff...
Samuel groaned and bucked into her mouth, fingers tangling in her hair—she loved when he got rougher, and gave an encouraging whine. She squeezed precum out of him with her lips, lapping it from the slit with her tongue.
“You’re such a tryhard,” Sam complained.
She flipped him off. “Mlehh,” she went, slipping her mouth free for a break. She nuzzled the shaft. “Don’t act like you don’t love this. Were you close that time?”
“It honestly can be hard for me to cum from head. Don’t take it personally.”
She’d heard that one before. Lilith rolled her eyes. She tucked a stray curl behind her ears and took him back into her mouth, making a ‘get on with it’ gesture.
He bunched up her hair in an impromptu ponytail, and held her head in place, now starting to fuck her face, bucking up, exactly how she liked it. The effort produced absolutely ridiculous and unsexy quacking sounds.
It was a good thing Lilith didn’t wear makeup, ‘cause it would get completely ruined two, three times a day from this. Thankfully, her gag reflex was virtually non-existent; that, at least, confirmed that this was low-key her life’s calling.
Lilith jammed her head down on him like she was trying to milk his soul. From the way Sam’s body went taut below her, she knew he was getting close. “Ohfuck,” he grunted. “Ohh, holy shit Lilly—”
She loved this. Making him lose control. Made her feel powerful and submissive at the same time.
His grip on her head tightened. Then Sam pulled out of her mouth altogether and started to stroke himself.
“Oh shit, you wanna...? Fuck, that’s kinda—oop! Oh, wow—whoa.” Lilith’s cheeks burned, and it didn’t get any cooler as warm ropes of cum splattered on them, and across her forehead, nose and lips. She flinched each time, and had to keep one eye half-closed from the cum.
“Sorry,” Sam huffed, not sounding sorry.
His cock never went soft right away, it still dangled in front of her face, so she licked the shaft from the base to the tip, and squeezed out the last bits of cum on her tongue, just to make him groan again.
Her brother arched his back, then jerked back pushing her head away, depriving her of shaft. “Hnng, fuck, stop. You insane little, fuckin’, nympho demon.”
“C’mon, I’m not that bad.”
Absently, she collected some of the cum from her cheek and stared at the gooey way it hung off her index finger, before slurping it up. She didn’t even grimace at the taste anymore; it helped to view it as a kind of ‘saltwater sauce’, in her opinion.
Sam was staring at her with that same grin of disbelief she’d seen a lot on him lately. Like he still couldn’t quite believe she was really like this.
“What?” she snapped.
“Fuck, I kinda wanna...” Sam trailed off, eyes flitting briefly to his phone. “ ... Nevermind, just a stupid idea.”
“Huh?” Lilith cocked her head, gears in her head turning “ ... You wanna take a picture, don’tcha? Gosh, Mr. Opsec over here. What a fuckin’ hypocrite you are.” She rolled her eyes. “Yeah, let’s send that shit to Google Drive. I love making incriminating child porn of my little sister.”
“Shut up, okay.” Sam blushed—a rare event. “I said nevermind ‘cause I realized it was retarded.”
“But you wanna?” She couldn’t help but smile. “I’d, umm, totally let you, by the way. Take it or leave it.”
He groaned, and moved to light his post-orgasmic cigarette.
Lilith got up, and inspected herself in Sam’s full-length mirror. It was smudgy and covered in stickers, and she could barely make out the cum, but she could see the stark contrast of all the hickeys and bruises on her pale skin from last night and all the nights before. Since the camping trip, she had been permanently marked by him, and vice versa, an unbroken streak. They ran from her thighs across her torso and up her neck. She ran her thumb across them and shivered.
Then she turned abruptly back around. “Take the fuckin’ picture, and send it to me.”
By the time they made it to breakfast, Samuel carried 200 MB worth of compromising nude material of her on his phone, and even a short video where he slapped Lilith’s face with his dick and fucked it into her mouth while playing rough with her hair.
She hummed an Arctic Monkeys song from their second album as she buttered her Nutella toast.
“Well, you’re certainly miss morning sunshine lately,” Annette observed, suspicious.
“Mhm,” Lilith agreed. “My depression got cured.” She met Sammy’s gaze in a staring contest as she said it, until he rolled his eyes and looked away.
“Good. That’s good,” her stepmother said absently. “Now if only we could get you to stop dressing like a Yugoslavian refugee.”
Lilith rolled her eyes. Thankfully, Allie stampeded down the stairs right then, and Annette’s attention turned onto her only child. “Allison! What did I tell you about the stairs!”
“Sorry, mom!”
At lunch, when Lilith slipped out of class first thing to avoid being cornered by Emmie, it was Sam waiting for her in the hallway. He motioned for her to follow him. She looked back over her shoulder to see Emmie, and scrambled along.
“What? D’you want another blowjob?”
He swatted the side of her head. “No, and please shut up in public about that, fuckin’ freak.”
“Whatever. No-one heard that, Sam.”
Sex did not stop them from fighting, it just meant they had a new way to resolve the accumulated tension at the end of the day. At school, they still had to at least pretend to hate each other, which came as natural as breathing.
He let her tag along with his friends, now, and sit with them at lunch, and in front of them, they acted suitably antagonistic and disinterested.
They reached the picnic table where Sam’s crowd gathered. Contrary to what she used to think, he did have more than two friends, but not everyone was quite as addicted to cigarettes that they’d sit there even when the weather outside sucked like Faye, Sam and Lucas. The others—a collection of band and drama kids and general stoners—only showed up about half the time. She hadn’t cared to learn any of their names, but she knew them all now.
There was Tasha, a severe-looking dark-haired lesbian, who was Belarusian or something and a Tumblr activist type. Then there was a black guy named Damon who had a really wholesome smile with a gap between his front teeth, and who was the group’s main weed plug.
Lilith rarely spoke to them still, she would just sit there and eat her sandwich, basking in their implicit protection from Emmie and the other bitches.
“—and then this freshman, god, he tries to buy an eighth with fucking Venmo Kids,” Faye cackled, making air-quotes. “Like, buddy, maybe that was your cue to figure out you’re, you know, below the age limit? Hah!”
Faye was the kind of person whose laugh carried across the courtyard before you spotted her. But you also spotted her quickly, with her ginger hair. She commanded attention. The opposite of Lilith.
Suddenly Tasha elbowed her. Lilith jerked and panicked at being addressed. “So, Allie told me you make art? What do you draw?”
“ ... Why does Allie talk about me. Can she not.”
“Oh, she loves you, don’t worry.” That was meant to sound reassuring, no doubt.
“I know. I still don’t want her to talk about me,” Lilith went, frowning. “How do you guys even know each other?”
“Tennis camp. And drama club. And we’re at the same parties sometimes.”
“Speaking of parties!” Lucas cut in, grinning. “You coming too on Friday or what?”
Lucas didn’t look like a Lucas, to be honest. He looked like a Josh or a Brad. A distinctly generic suburban jock archetype. Polo shirts and khakis, goes to the gym, smells like cologne ... hanging out with the alternative crowd, for whatever reason. Lilith didn’t quite get him yet.
It took a moment for her to process that the question had been directed at her. “ ... Huh?”
“Friday. My party.”
Just as Lilith opened her mouth to answer, Sam cut in. “She’s not much of a party-goer, I’m afraid,” he said, rolling his eyes dismissively.
Lilith huffed. She turned to Lucas and answered, “Maybe. I’ll let you know. You can add me to the group chat or whatever.”
“What are you talking about?” Sam was actually laughing. “No way you’re going.”
“What’s that supposed to mean? You don’t get to decide what I do, Sam.” She crossed her arms.
“No, that’s not ... I mean.” Now he just sounded bewildered and exasperated. “You hate crowds, Lilly. And noise, and normies and stuff like that.”
“But you know I’m really fun when I’m drunk.” She smiled sweetly. “Remember that one time?”
“You’ll regret this,” he went, raising a finger all dramatic, “but fine.”
“Okay! You guys are really weird.” Tasha shook her head. “But I wouldn’t mind seeing you cut loose, cutie.”
Lilith’s head whipped around and she blinked in system error. “ ... H-Huh?”
“Stop it, Natasha, you fuckin’ perv. That’s my little sister. And she’s straight.”
Lilith was about to open her mouth to object I’m bisexual actually, but then the bell rang, saving her from further unwanted human interaction.
As everyone gathered their shit, Sam fell into step beside her. “The fuck are you doing?” he hissed.
“Going to my first party, I guess.”
“You’ll hate it.”
She rolled her eyes. “I know.” But I’ll hate it even more if you’re going without me. She’d torture herself all night, thinking about him fucking some slut. It was a lose-lose situation.
“Why even go, then?” he pressed her.
“Afraid I’ll embarrass you?”
“That’s pretty much a guarantee.”
Lilith rolled her eyes. They’d reached his classroom and had to split up. She took a deep breath and whispered, “ ... Just remember what happened last time I got drunk.” She scurried off without waiting for his response.
Friday afternoon, the day of the party, Sam was playing Xbox, trying to ignore Lilith’s frantic pacing around their room. Every single item of clothing she had worn in the past year was piled on his couch, rejected for either being too childish, too standard-attire, or too tryhard.
After years of goblinhood, it was now time for Lilith’s debut as a normal girl who went to parties. Heh. Who am I kidding. But she’d make an effort to be pretty, for Sam. That was her whole rationale for going, really—to keep an eye on him, or rather to keep his eyes on her.
But ... she faced some logistical issues. Firstly, all other girls in the world were much hotter with bigger tits, and it was hopeless. Secondly, she didn’t own any proper making-an-effort clothes, because she always dressed for the opposite, to minimize her shape and hide away all day.
“ ... Sammy?” she pouted. “Can you help me decide?”
Sam sighed. “You’re really overthinking this. I’m putting on my nice jeans or whatever, but that’s it.”
“I’ve never been to a fuckin’ party before!”
“Yeah. Exactly. So just take it from me: everyone’ll be far too faded to give a fuck about what you’re wearing.” His eyes were still fixed on the TV screen.
“So I should just go in my regular clothes, or...?” She really just wanted him to express a preference about her appearance, of any kind. It made her feel nice.
“You should, at the very least, stop making it my problem,” he snarked.
Lilith huffed and glared at him, then plopped down on the pile of clothes, dejected.
“Hey.” He looked over, finally. “Why don’t you wear that dress Allie got you for Christmas?”
“Ah.” That was solidly in the tryhard category. She shook her head. “Dude, nahh, no way. I can’t wear that.”
Samuel smiled, and turned back to the TV. “Sure you can. Just trust me.”
“You’re the last one I’d trust,” Lilith sulked, the gears in her head turning slowly.
“ ... Didn’t you just ask for my opinion?”
She groaned. Anxiety about trying too hard clashed with desire to do exactly what Sam wanted at all times. “ ... But I don’t wear dresses. I don’t have a figure for it. I’ll just be a stick wrapped in a plastic bag.”
“You do have a figure, ‘cause of your butt, it’s cute. You’re like a sad, skinny little pear.”
Lilith stood up abruptly.
She held the dress up in front of her, feeling ridiculous. Yes, it was an A-line sundress kinda thing, thankfully not form-hugging—the kind that could be construed as ‘elegant’ and ‘goth-adjacent’ and that Lilith might actually wear. In theory. Allie’s sense of style and sensitivity guaranteed as much.
However, Lilith’s anxious brain had decided that she could never wear this kind of thing to school; dressing all pretty drew Emmie’s attention, who would surely ruin it forever by making some stupid joke that she’d forever associate with the dress ... she just couldn’t do that to Allie’s present.
She’d only worn it one time, to uncle Asher’s funeral.
“So put it on, Lilly,” Sam nagged.
“I hate you,” said Lilith, as she slid her t-shirt off and everything else. At this point, changing in front of Sam didn’t feel weird anymore—he’d seen it all, and somehow he even liked it.
Lilith wasn’t wearing a bra. The dress slid on smoothly, thankfully not the kind that needs help to zip up, it didn’t have a zipper at all.
She did a little twirl; it felt strange, this mix of shame and pride. Almost sexual. While the dress did little to accentuate her chest, that was probably for the best; it did an unexpectedly great job suggesting an bigger butt than she really had, though, with the flared pleat skirt-like bottom.
As not-terrible as it looked, the dress felt ill-fitting. Not in the sense that it didn’t fit her frame; it fit stupidly perfect, because of course it did. But Lilith didn’t do dresses. Her arms bare felt wrong, so wrong, where she usually wore long-sleeved sweaters.
She shucked the dress off again, which Sam took advantage of by sliding a hand down her belly and between her legs. She pressed her thighs together to enjoy him there for a brief moment, before pushing him away.
“No. Look.” She’d had an idea. From his dresser, she produced a white button-up shirt he had clearly wore about as often as she’d worn this dress. She put it on, buttoned to the top, and then put the dress back on over it, for something approximating goth chic, and a way to at least feel covered, like she liked.
“Okay, that’s actually kinda cute,” Sam admitted. “Don’t wear a bra under that,” he instructed, as his hand wandered and groped her tit, before giving her nipple a little pull.
“Stoppit. You’re such a perv.”
Sam rolled his eyes. “Uh-huh. You don’t get to say that. What’re you then?”
“A victim of your predations.”
“That’s not even a word.” He squeezed her butt, possessively.
“It is, you’re just a moron.” She turned in his arms and hugged him sheepishly because the eye contact in the mirror was getting too intense. “ ... So, you don’t think I look like a freak?”
“Of course you look like a freak. But that’s good. That’s your vibe. Y’know what they say about lipstick on a pig?”
She punched his chest.
“Oomf,” he went. “Guess that’s deserved. Speaking of lipstick, how about it, huh?”
Lilith scowled and pulled away from him, crossing her arms. “What about what?”
“ ... You gonna put some makeup on? Or what?”
“What, you think ‘cause I’m a girl, I automatically know how to do that shit? ‘Cause too bad. I don’t even own any.” That, at least, was not on the agenda tonight. And thank God for that.
“I know someone who does.” He whipped out his phone and started typing.
“Oh no. No, no no no. Don’t—”
“YESSS!!!” Allie cried out, when she stormed into the attic thirty seconds later like the fuckin’ Kool-aid man. “Lills! Yes! Ohmygosh! You’re wearing the dress!!! With a shirt?? Whoa!”
Lilith sighed. “Yeah. I am. So I guess you wanna help me with—”
“Yup!” Allie sprint-tackle-hugged her, tight enough that it made her gasp. “Absolutely! Finally! I love it! I love that you’re asking! I’ll make you sooo frickin’ pretty! C’monnn!”
Lilith was dragged down the hall to Allie’s room, which was Madam Umbridge levels of offensive pink and probably contained more individual female cosmetic products than there were atoms in the observable universe. Allie was already getting out her makeup bag and sitting Lilith down in front of her big mirror.
“I’m so glad you’re finally asking me for help,” Allie said for the fifth time, as she started to put on Lilith’s eyeliner. “Gosh, I’ve been waiting for this...”
“Your enthusiasm is freakin’ me out,” Lilith commented. “Definitely second thoughts...”
“Oh hush! Now stay still. Don’t fidget, or we’ll have to start over.” That threat was enough to silence Lilith.
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