Lisa comes up the stairs and finds Bart's bed empty. She follows the sound of creaking bed springs to their parents' room.
"You didn't say which bed," Bart informs her.
"Go to YOUR bed!"
"Make me!"
Lisa lunges to tackle Bart while he's jumping on the bed. He doesn't get out of the way in time, and she tackles him to the bed, lying on top of him, straddling him.
As he struggles to free himself, he bumps into her crotch a few times, and he gets hard, thus giving him an idea.
"Lis, I never knew you felt this way!" He jokes, hoping to gross her out and make her get off him.
She replies by grinding her crotch against his. "Well, if this is the only way to get you to behave for me, maybe you and I could..."
He's shocked into compliance. "Woah! Wait, you'd do that? With me?" She feels him growing harder at the idea.
"Desperate times call for desperate measures in the babysitting game. But only if you promise to behave. For once."
"Oh man, you got it, Lis."
She pulls her dress over her head, revealing her skinny yellow torso, her brownish-yellow nipples already hard with the cold night air, and more than a little desire. Is she really doing this? And with her own brother? Well, it's not as if Bart didn't have his charms. Despite his less-than-stellar academic performance, he did possess a kind of intelligence when it came to mischief and smart-alecy remarks. And if losing her virginity to her brother was what it took to maintain her reputation as a babysitter - not just to their parents, but to the whole of Springfield? In the long run, that'd be a small price to pay.
"Okay," she says, "now let's get that shirt off."
She helps him take off his orange shirt, and she studies his kind-of tubby prepubescent torso. At this age, there was barely any difference between the torsos of the two siblings.
"Now shorts?" Bart asks, hopefully. Lisa nods in reply and climbs off him so they can both remove their underwear.
Lisa's small white cotton briefs are already damp with anticipation. Any doubts she had at the start are virtually gone, replaced by lust and anticipation. She's now fully nude in front of Bart, as she has been hundreds of times, but never like this. This time, it feels different. Grown-up. Naughty.
She looks over at Bart, who has just removed his underwear too. His uncircumcised penis looks much different than how she's used to seeing it. It's standing up straight, longer and thicker than usual, and the tip is dripping with a clear fluid - precum.
"Oh my gosh," Lisa whispers in awe. She needs that inside her, more than she's needed anything in life.
Bart lays back down on his back and Lisa straddles him once again. She grabs his hard little cock, 4 inches at most, and guides it inside her moist, virgin pussy.
There's some resistance as Bart's cock presses against his little sister's hymen. But she's determined, and lowers herself further onto her big brother's erection. It breaks, and with it comes a wave of sharp, stinging pain. To the eight year old girl, it's almost pleasurable. She bites her bottom lip and rides out the pain. They both moan as Bart's cock fully enters Lisa's pussy, brother and sister losing their virginity to each other.
"Now what?" Bart wonders.
"I think we're meant to, like, hump?" Lisa theorizes. "Kinda like this, maybe," she says, then starts moving her hips, lifting her ass off Bart's thighs briefly, then slides back down his hard cock.
"Oh yeah, that feels so good, Lis," Bart informs her. "Keep doing that." He gently rests his hands on Lisa's undeveloped hips and looks up at her face, smiling.
"Mmm-hmm," she replies, letting instinct take over her body. She starts riding her big brother's prepubescent erection, bouncing her body on top of his. They both moan in delight, thrusting together in their parents' bed, the door wide open, without a care in the world.
Barely any time passes before Bart feels a new, almost familiar sensation building within his dick. It's like the need to pee, but there's something different about it. It feels too good to be the pee feeling. Before he can articulate these thoughts to his little sister, Bart was in the throes of his first orgasm. His whole body tenses, his toes clench, he thrusts his hips skyward. His body quivers and his cock pulsates inside his sister while it pumps clear boycum into her young pussy. "Oh god," he groans, "Lis, that was...what was that? It was awesome!"
"I don't really know, Bart. But I'm glad it felt so good for you." If this is all it takes to turn even the most unruly boy into putty in her fingers, babysitting was going to be a breeze from now on. "I liked what we were doing before that happened, too," she confesses.
"Just let me catch my breath a bit longer and we can keep doing it," Bart promises.
"I can think of a way to fill in time," Lisa replies. With her brother's cock still hard inside her, Lisa leaned down and pressed her lips against his. Now that she'd lost her virginity to him, Lisa thinks it's only fair that Bart should receive her first kiss, too.
Bart's surprised at first, but then quickly softens his lips against his sister's. He puts his hands on her back and holds her nude body tight against his. They hold the kiss for a while, then Bart parts his lips, causing Lisa to do the same. His warm, red tongue slides into her moist mouth and rubs softly against her tongue. Lisa responds by sliding her tongue into Bart's mouth, their tongues dancing and their jaws moving synchronously. Lisa wraps her arms around her brother's neck and cradles his head.
Before they realize it, their hips are moving again, grinding their hairless crotches against each other's. Lisa's untouched clit starts to make contact with Bart's pubic bone, and wonderful new sensations begin to occur in her inexperienced body. Short warm, tingling pleasure waves radiate from her pussy. She loves the sensation, and her body yearns for more. She angles her body slightly, grinding her clit harder against her preteen brother's chubby body. Now that she's found the right spot, she starts fucking him harder and faster, chasing her first ever orgasm. She breaks their kiss and her rhythmic short, high-pitched moans fill the room, drowning out the sounds of her pearls clattering with the motion.
"Oh Bart, yes, that feels so good," she tells him breathlessly. "Just like that; keep it up," she begs.
"You got it, Lis!" Bart looks deep into his sister's eyes, now determined to make her cum like she made him cum barely two minutes ago.
Lisa's fucking her brother as hard and fast as she can, groaning with each thrust, their little bodies making wet slapping sounds that echo down the upstairs hallway. "Oh Bart," she repeats over and over. Soon, she feels her pussy tighten around his hard boycock. Her cheeks and chest flush red. She goes cross-eyed and her tongue lolls out the side of her mouth. She moans and groans with ecstasy as her body convulses in her brother's arms. Her usually-active mind is now completely blank, swimming in a pool of pure pleasure.
All the while, Bart fucks his little sister as hard as his body will let him. He longs to feel like Lisa does again. Her tightening pussy is certainly helping in that regard - his cock is being squeezed like her life depends on it. And holy cow, it feels amazing.
"Oh Bart, that felt so good," Lisa tells him, once the euphoric fog has lifted from her mind. "I've never felt like that before." She kisses him again, sliding her tongue into his mouth. He sucks her tongue and grabs her ass in both hands.
It's not much longer before Bart feels that feeling building inside his cock again. He moans deeply and grips Lisa's soft little ass tightly. He arches his back and his cock sprays another coat of his empty cum deep inside Lisa's pussy. Throbbing with each shot, his warmth fills Lisa. Breathless, they moan together as they kiss deeply, holding each other tightly.
As Bart's erection finally starts to fade, his cock slips out of Lisa's opening, spilling their combined juices onto Homer and Marge's quilt.
Lisa eventually breaks the silence. "Oh Bart, that was incredible. Can we do it again? Please?"
"I don't know, Lis. I think it's a bit worn out for now. I'm not sure when it'll be able to get hard again. As much as I want to."
Lisa suddenly realises she's left Maggie alone downstairs all this time. "Oh no! Maggie!" She races to put her dress and panties back on. "While I'm dealing with Maggie, you'd better clean up the mess on the bed."
Bart's mischievous smile returns. "Well, that depends. Are you asking me as my babysitter, my sister, or my lover?"
"All three! Now do it, before Mom and Dad get home," she demands as she leaves the bedroom to find their highly caffeinated baby sister. She leaves the room, then returns a few seconds later. "And once the bed's clean, go to your bed. I'll be back to...tuck you in shortly," she teases with an alluring smile.
Bart, spurred on by the idea of more sex, grabs some tissues and starts cleaning up the evidence of their incestuous love making. As he does, he tries to think of suggestions for Homer and Marge's next date night.