Make her a (clean) woman.

You bend your knees to run your manhood parallel to her slit, and the warmth you find there, if not exceptionally wet, reminds you of what you've been denied for so long. "Isabella," you breathe into her confused face, "we shouldn't delay... turn around and bend over, and do your best to stay still." She nods, offering a weak smile. With one last, worried glance down to your unit, she turns around and puts her hands on the porcelain fixtures on the shower walls. "No, honey... put your hands on the edge of the tub."

"But... but daddy..."

"This is for your own good, sweety," you chastise her. Reluctantly, she lets herself bend over further, grabbing the edge of the tub that was at level with the middle of her shins... and giving you full access to her bald twat. You eye her **** behind as you gather a generous wad of spit in your palm and and wet the head of your angry erection. "Now since this is your first cleaning, and a hymen formed... this will probably hurt. But to make sure it feels better from now on, we'll do it every day along with a bath." Your head glistens with the wetness you wish she had, and guide your helmet against her breach. Her plump nether lips expand as you pierce the space between, and the narrow canal you find almost makes you cry. "Honey..." She starts to instinctively move away, but you hold onto her hips to anchor her to the spot. In her mind, she has no reason to flee save the trepidation of pain... and yet something is there, screaming in her instinct, that there is something amiss here, something she isn't aware of... it begins to build, this warning system, it's **** cry to tell her that she doesn't want this, and that her life will be ruined if she doesn't leave right-

You drag your prick into her, your substandard lubricant serving just well enough to nestle you inside her, pushing against the sacred barrier that marks her innocence. The presence of a human being inside her for the first time freaks her out more than she could ever be prepared for, and she begins to sputter as she tries to rationalize the fear building in her. "D-Daddy, this feels... so strange, I don't know, it kind of hurts. I know you said it would, but... but it's..." She can't put her finger on it. It becomes harder to reason when you reach around her hip to violently stimulate her clitoris. "D-daddy! That's... t-that's my..."

"Shh, honey," you coo, trying to focus on the tiles to keep from coming prematurely. "I'm just trying to help you hurt less..." She struggles to quiet her grunts as you grope her clit, and your other hand rubs her quivering back. "Honey, remember how I said fathers and daughters share everything?" She nods with a shaky sigh. "Tell daddy what gets you sexually aroused... and we can use this to make it all less painful."

"I..." She covers her mouth as her answer becomes a yelp, and slowly your dick begins to slide around in the tiny space you've allowed yourself. "Sometimes... I imagine... I-I imagine my..." Her hand lifts up from the tub edge... and caresses her breast. You waste no time, and replace her grip on herself, kneading the handful of tit you find there. She yelps under your stern grasp, her opening crushes you in response, and you can control yourself no longer.

"Don't move!" you hiss through gritted teeth. Your own breaths and gasps begin to roll out, and as she looks behind to you in confusion, she feels your orgasm rushing in, pouring into her and welling against the porous barrier of her hymen. She moans in pleasure and pain as the seed splashes against and through its openings, quickly filling the front of her vaginal tunnel and slowly bubbling and leaking into her birth canal proper. You sigh in relief, still squeezing her breast, as your orgasm subsides... but her naked, quivering back, the feeling of your seed and her moisture drifting onto your fingers as you **** her, knowing that your sperm is already on a long road to her unprotected womb... it keeps you hard, and now with enough lubricant to finish.

"Dad, are we... are we done...?" She whimpers, and her pussy clenches you as it tries to expel seed and cock alike.

"We're ready to begin."

"Wha-"

You grip her waist, and bring her very core down onto you. Her hymen is barely a protest as you sunder it in this new violation, your cum-covered prick rampaging until it slams against the cervix at the back of her barely-aroused vagina. Her whimpering turns into a howl of violation and pain, and you savor it as you imagine your wife watching you put a child into hers, the child she wouldn't have with you. With one orgasm spent, you're able to remain calm as you enjoy the squeezing, unhappy flesh impaled on your manhood, and give only a token rub of Isabella's lower back as she cries.

"Daddy... this hurts so-o-o muuuch...!"

"We're almost done, baby... yeah... almost..."

You withdraw half of yourself from her deflowered cunt, admire the mixture of white and crimson on your shaft, and then shove it back in. One more powerful, merciless hump, and you're off to the races, bouncing her lithe body on your prick as you ravage her. You grab her shoulders and lift her up, hugging her to you as you stand at your full height, lifting her legs off the ground until they flank your own as you hold yourself in her crotch. With one hand cradling her torso and twisting her nipple, and the other furiously abusing her clit, you continue to fuck your step-daughter, enjoying feeling her body as she half-resists, half-surrenders in your masculine grasp, her cries turning into moans and mixing into some kind of confused shame. "Is that starting to feel good, baby?"

"Daddy..." she whimpers.

"You're almost clean, honey... I just have to give you one... more... injection...!" You hug her downwards and into you, impaling yourself back into the tight muscle of her cervix, and come again, your weaker batch making up for volume in precision: it squirts against that tiny gate and seeps into her womb, the first of daily waves of your seed in hopes of impregnating this fertile teenager. You sigh happily into her ear, giving it a lick as you do. "There you go, baby... it'll only feel better from now on, I promise." She nods, tears streaming down her face. She looks down at the tub floor, where droplets of your jizz have made chaotic patterns. "Don't worry honey, we shaved you clean: you can't get pregnant... and a father's semen has hundreds of health benefits for a young daughter. I'll teach you more about it later." You barely manage the words, so out of breath as to wonder if you can finish giving her an actual shower.