Your darling sister helps to preserve the mood

As you crawl backwards to give your oh-so-romantic father a better chance to cover your pubescent tits with his cum, you accidentally bump against Gwen's backpack! A package of Plan B pills drops out of a pocket and tumbles forward, far enough for you to take notice. Since the lighting in the tent was awful you remained clueless as to what it may be, until you raise it up to your eyes... Morning after pills? That's... neat? Why did Gwen have those anyway? You should probably hide them quickly before your dad notices and ---

A much bigger and stronger hand snatches the package out of your grasp and you hear your father's voice following shortly after. As far as he was concerned, this was of course a VERY welcome surprise. An early Christmas gift and an opportunity to blow his entire load of cum in the DEEPEST corners of your cunt! After all, he had already buried his unprotected appendage inside your womanhood. It's the logical next step to redecorate your interior and paint those insides a nice pearly white with his smelly semen. To him, that option was WAY more appealing than just cumming on your small breasts. "Where did ya find these? Oh you are just an angel, sweetheart! Did you bring these for emergencies?"

You're doing a good job of hiding your horrified expression.

"Hold on..." you plead as you reach for Gwen's backpack and take a closer look at the specific pocket. There's also a small pouch inside, and you reach in to find... a diaphragm? Shit! On one hand you're of course thrilled to see so much stuff to prevent pregnancies... on the other hand, your dad had been seconds away from covering your teenage breasts with his cum! You could've easily used a towel to wipe the dangerous goo off your chest and then move it to a place far, far away from yourself. It would've never gotten even remotely close to your vag!

But now, you can either deny him further access to your womanhood and risk pissing him off, or use those new tools to make it proper 'safe sex'. Considering his ripe age, there was a good chance that he's gonna have only a single cumshot stored inside his hairy ball sack. If you help him to get off, he's gonna go sleep and you will have nothing left to worry about. You just have to make sure to do this right. "Sure! I can help you out," you offer. It's weird saying it like that. You are offering your twat to help him climax, as if it's some kind of household item... is his attitude rubbing off on you? Even you are beginning to see sex as little more than a necessity that needs to be done at times. "Okay big boy, give me a second and we can jump right into it."

You grab the diaphragm tightly and, whilst still lying on your back with your legs spread apart, guide the latex dome between the sore lips of your vagina and wriggle it inwards. You keep on pushing against it, coaxing it into the far back of your cunt until it snaps in place around your cervix. With your finger buried so deep in your snatch, you give the rubber thing a few solid taps to make sure it's secured in place. You've got this under control. Diaphragm AND morning after pills? Easy.

Ah-choo!

Both you and your dad get startled for a second upon hearing the sneeze, and both of you stare towards the origin of the noise to see... Gwen! Cuddled up underneath her blanket, you could see her eyes open and awake. With a faint blush on her cheeks, she had been watching you insert the diaphragm into your vag. It takes you another second to fully comprehend that she had been watching you prepare for sexual intercourse -- with your own father -- and apparently hadn't said a word! It's hard to tell for how long she had been awake and looking already, but it can't have been more than a minute. As far as you know she had never even watched porn... so this was bound to be a situation that was intoxicating to her senses! Even more so with those male hormones that now coursed through her blood. Her usually so pristine intellect was taking a backseat to make room for her instincts and basic desires. It certainly explained why she hadn't stopped you as soon as she was awake enough to notice what's happening. You lower your gaze a little, and see the area of the blanket that was concealing her crotch was moving up and down. She's jerking off while watching you! And she also seemed particularly aware of how the diaphragm is going to be the only thing standing between you and an early pregnancy. You're at the perfect child-bearing age.

In the meantime, your dad's fat cock was resting on your stomach right by your bellybutton, highlighting just how deep his sausage could bury itself inside your snatch if you allow him free reign. Gwen inhaled deeply, and you couldn't tell if she was simply excited as hell, or if she was intentionally inhaling that musky scent of your lady bits. You could clearly tell that she was anticipating the show, getting to see actual penetration for the first time -- even if it was her little brother who was going to receive daddy's pussy-splitting manhood. Even back when you were still a guy, your own penis wasn't even half as monstrous as the scary tool he's wielding down there. This was a risky situation, and only your sister and you were aware of what's at stake. There was no need to exchange words.

And while the two of you were pondering the sheer importance of this event, your father simply gave his dick another stroke. A fat drool of pre-cum oozed onto your flat belly and formed a tiny puddle. He then grabbed a good hold of your feet again and simply tossed them up onto his shoulders before lowering all of his weight on top of you! He was done waiting. This time around, he was pretty much folding you in half! You moan at the discomfort, and groan when he wedges his coke can-sized appendage back into the tight embrace of your vag. However, you groan even more bitterly when he punches the far back of your baby chamber with that monstrosity!

"Ouch, oofh, ouch stop!!" you hiss sharply! A STINGING PAIN filled your loins! Stop, stop! Thrust, thrust! He didn't stop! Considering how little respect he had for you, he might even think you are some stupid middle-schooler? Your hairless peach certainly looked like it belonged to a young girl. This is not good! And right now, all he cared for was the vice grip of your cunt. That small bit of paradise between your legs was right now the only part about you that mattered to him!

"It's just a dick, you're overreacting." Your father's words didn't soothe you at all! "There's something wrong!" you hiss back at him! Every thrust made you flinch and squirm on the spot, it's like someone was kicking you in the imaginary testicles! "Ahnn, ouch! The diaphragm! S-stop hitting it!" The artificial dome that ensured your purity, was also expanding against some very tender spots inside you with each impact! It felt TERRIBLE!

Your father however didn't even know how to take no for an answer, he kept on pounding your twat into submission, making you cry out in exchange! "Just deal with it a little longer, I'm almost there!" His voice was rough and heavy, full of a dire need to empty his balls. At least it won't be long before you can leave the tent, squat down to pee out his sperm, and then go back to rest without having to worry about a single thing anymore. The knowledge that he's literally going to pump your vag full of semen and that you will have to awkwardly try to pee it out was... gross as hell of course, but a necessary evil. It hurts like fuck but at least you can't get pregnant!

A soft, faint noise came from the corner of the tent. It was almost impossible to hear over the sloppy sound of sex. Daddy's crotch slapped wetly against your labia with each demanding shove forward. "Why uhmmm..." Gwen was stuttering shyly, her cheeks even more red than before. "Why don't you just... uhmm... remove the dia-diaphragm... she can use the mo-morning after pill anyway..."
Did she really just say that? It's the first time you hear her stutter... her voice was silken sweet and embarrassed but also drunk with lust. "Pull it out of her... ma-make her cervix naked again." Wha... wait what? That's a TERRIBLE idea, sis!

"Now there is an idea!" Instead of awaiting your opinion on the matter, your dad simply kept your legs hiked HIGH up while pulling his dick out of your swollen and sore sheath. The red lips of your cunt twitched rapidly in response to the sudden emptiness in your private parts.

His fat fingers replaced his shaft and invaded your twat, sinking in deep... searching... "Wah? H-hold on just a second! That's MY pussy!" you point out the obvious, he was violating your privacy! His fingers kept on wriggling around, prying you open and looking for that artificial birth control device that you had kept hidden somewhere in the far back of your little vagina. Your remarkable tightness did little to prevent him from jamming his digits deeper into you. "After our little bonding moment I dare say that your pussy is our shared property, yeah? I think you even got a bit of my pre-cum in there already, so don't be such a prude," he responded cold and emotionless. He's acting as if spilling his pre inside you was doing you a huge favour just because it was lubricating your cunt! All it did was turning you into more of a fleshlight, since he didn't bother getting you aroused and wet! This is ridiculous! The seconds felt like hours while he was fishing around inside you! You squirmed awkwardly in an attempt to make it obvious that you are NOT ok with him attempting to remove your only contraception! You're struggling even more feverishly when he gets closer to what he sought. Suddenly, his fingers managed to touch the thing. It covered one of your most sensitive bits, so it was easy to feel when he hooked a fingernail underneath the edge. Right now, that diaphragm was the only thing which prevented him from inseminating your stubborn pussy.

And with a simple flick, he loosened it and began pulling it out of your adoringly tiny lady parts.
Just like that you were laid bare...
Completely naked. Fertile. Unprotected.
His dick was already jerking energetically and he could barely wait to stuff you completely full of his masculine baby-maker.

The three of you -- Dad, Gwen and yourself -- looked at the pale latex object that he was holding between his fingers. With both hands, he grabbed each end of the diaphragm... and easily tore it in half, splitting it apart! You struggled harder to get free, but with your feet pinned all the way back and nearly touching your head, there's not much you could do!

Gwen's hand moved faster, stroking her girl-cock under the cover of her blanket. "Sto-stop moving around so much," she insisted shyly with her eyes fixated on your exposed womanhood. Her idle hand reached for the package of Plan B pills and she pulled it back to her side of the tent, hiding it under her pillow! "Be a good girl for him... You know... Like uhmm.... Be friends with benefits... yeah! Yeah...!" Her breathing came heavier while you were left speechless. Where did she even learn that term!? Fuck! "Be friends with be-benefits with daddy... or I don't give the pi-pills back!" Her hand moved quicker still, lavishly pleasing her male appendage!

She REALLY plotted to ruin the innocence of her 'little sister'.

Your father in the meantime shifted his hips backwards and allowed his bulbous cockhead to slide south of your bellybutton, across your pronounced pubic mound, and between the loving embrace of your labia. Those soft lips which were meant to conceal the entrance into your body, were now hugging the purple crown of his erection and helping to guide him towards the small opening. Naturally your mood was all but ruined, you felt dry as the desert. But the ample amount of pre-ejaculate his dick had drooled all over your insides, during the brief lovemaking from earlier, was enough to keep your vag slippery and ready.

He's more than twice your age and eagerly anticipated to be back inside your snatch. This was the first time that Gwen watched a couple having sexual intercourse, so her heart was beating like crazy while watching this private show! All you could think about was the heavy, hairy chest of your dad pressing firmly down against you, and the thick scent of sweat that lingered all around the tent from all the desire and lust in the air. It was difficult to think clearly because of how suddenly the whole situation had changed. Are you still in control? As long as you can take the plan B pills you should still be in control. Your sister excitedly watched your rapid journey into maturity -- he's going to turn you from a girl, into a woman! And without any barrier inside you, it will be up to him to decide just how deep you're gonna get that injection of potent cum.