Gwen invites you into her room

It was a reassuring feeling to be clean again, and taking a shower in general was... probably a good idea after getting laid multiple times. Over the span of an hour, you went from being a full-on virgin to having had sex twice in a row -- and receiving your very first creampie in the process. A cold shiver runs down your spine... the thought itself remained pretty revolting.

Regardless, you wrap a towel around your midsection and comb your hair. **** of habit, if anything. Though you usually had only an inch of hair to take care of, instead of what you've got now... ten inches? Twelve? No idea, this body still has some mysteries. You can inspect yourself only for so long before it feels too surreal! The sooner you get back into your former body, the better.

On your way back to your own bedroom, you don't even notice Gwen's door opening until she -- rather impolitely -- coaxes you in. "Hey slut, get in here for a second." Her fingers grasp your wrist and abruptly pull you into her room. The name calling is really ... off-putting, and something she usually doesn't do. You must've made a really bad first impression to end up being one of the select few that she has such a dislike for...

"Get up on the bed." Her tone was demanding. You briefly ponder your options but quickly decide to follow along with her request. Considering the disdain she's got for you, it's probably in her best interest to help making sure that you produce no offspring, and that your interactions with other people are kept to a minimum. So! Since she's an ally, you get on the bed. She begins crawling up onto the bed herself and makes sure you remain on all fours while her hands remain busy with whatever she was up to on her own side of the bed. If anything, having her behave like a bitch is beneficial to you! She'll keep helping you to avoid a pregnancy -- since that would tie you to her little brother -- and she will keep on makings things brief to spend as little time with you as possible.

She grabs the bottom edge of the towel you kept around your waist, and raises it up just enough to expose your perky butt as well as your juicy cunt. There's the short sensation of something slippery rubbing up and down the length of your slit, enough so to raise your suspicion, but just as you're about to look back at her you can already feel something sliding right on inside your twat and stretching you open! "Ahnn!"

One of her lubed fingers perhaps? Maybe she's applying an ointment? Something to reduce your fertility? That assumption goes right out the window upon feeling both of her hands snugly grabbing the cheeks of your bum and giving them a tight squeeze. So she's not using her fingers to penetrate you...? Then what the hell is she shoving into your lady bits?! It feels smooth and wet and rigid...

"What are you doing!?" Your voice is shivering and confused, it was still a very alien sensation to have something inside your body. Inside your crotch. Like a violation of your privacy, you know? It was a very distinct feeling to have the velvety flesh of your pussy wrapping around something that isn't meant to be in there.

Since Gwen wasn't answering and instead kept pushing the foreign object deeper inside, you lower your head a bit further to look between your legs. At first glance you can see that your sis had taken off her pants and her smooth pale skin was visible. At second glance, you could see... a hefty pair of testicles attached to her crotch!? Next up you notice something even more surprising attached to her crotch, hints of some... shiny red appendage, half of it already buried inside your lady bits! It didn't quite look like a penis, not a human one anyway. It was far too red for that, not to mention it was glistening and visibly... excited. And gross. There's also a noticeable bulge near the base of the shaft, which gave it an even more unusual appearance! Hold on... she wasn't just acting like a bitch. She is a bitch, in heat! That's a dog's dick that she's wielding! What the f---!"Gw-... Gwen! I know what happened to y-you! Some witch did this to you, right?" Your hands grasp the soft bed sheets. The unpleasant sensation of having something entering you was beginning to feel really weird! She was reaching a depth that felt pretty... intimate. Which shouldn't be too much of a surprise. She was literally having sexual intercourse with you! Your own sister was forcing her male appendage -- whatever it may be -- into your cunt!

"Can't you just shut up? I woke up with a dick, so what. Let me get it wet, it's all you're good for anyway." Stupid Jimmy, this is his fault for pretending that you're just his girlfriend instead of clarifying it all to begin with! Now she thinks that this is actually something you're into! To be used like an onahole. Seriously!? If they're so **** to stuff their dicks into something they should seriously just buy a fleshlight, this is humiliating!

At the same time, she began to gradually slide her dickmeat back and forth within that tight sheathe of yours. It was too late to tell her the truth. It would probably be horrifying to someone as stubborn as her to realize she had sex with a sibling -- worse yet, with her brother stuck in the body of a chick. Telling her that now would traumatize both of you for the rest of your life. But if you can't tell her that you are under the influence of a spell, what CAN you tell her?

It didn't help that you were acutely aware of every movement she made inside you, the way your flesh clung to her dog-shaped dick. Should you question her how it feels? Is she even aware that this is not what a human cock looks like? She might not even be aware that she got tricked with an animal's cock, for all you know she may think this is perfectly normal. You can't help but notice that it is ANYTHING but normal however when she begins pushing even deeper inside your twat, and her knot is beginning to tease the lips of your pussy! A slippery kiss that allowed your mismatching genitals to get very familiar with one another.

"Gwe- Gwen! Slow down," you insist, but she tightens her grip on your ass instead. "Shut up, I think I have it figured out," comes her agitated response, and without warning she's suddenly slamming her hips forward to break right through the resistance of your womanhood -- her knot pops right on inside your cunt and stretches you WIDE open! Fuck!! At the same time, you are joined by the contrasting sensation of Gwen's soft crotch pressing warmly and gently against your backside. Her canine cock found a welcoming home inside your sore womanhood.

"Nnh! Ahh! Ahnn!!" Gwen inhaled sharply and you assumed she was just about to sneeze or something, but instead you are suddenly treated with the dominant, eager throbbing of her appendage! "Gwen!" It pulsed and thrashed against the soft comforts within you and spat multiple wads of girl-cum into the deepest reaches of your slit! The second creampie of your life, and it's provided by your sister of all people... what the hell!! You attempt wriggling away, but feel the way your pussy lips held on to her bulbous knot for dear life! It's like those two were glued together all of a sudden! "Take th-that thing outta me," you demand quite grumpily, now that she had succeeded in inseminating your teenage cunt, just like your little brother had done. The pungent smell of semen wafts up from between your legs, erasing any remaining doubt that she had pumped you nicely full of spunk. The heat of fresh sperm is also helping to warm your belly...

Considering how small and tight your cunt is, it's EXTREMELY good at drinking up crazy amounts of cum. It's probably part of the reason why the thing is so irresistible to your siblings, it's the perfect lil' cumdump... and you're the only one who isn't pleased with that.

A sharp slap across your rear brings you back to reality and Gwen's heavy but satisfied breathing. "That was kinda nice," she sighed. "First time I got to use the thing for real. I can tell why Jimmy likes you, sex is a nice stress relief! I still think you are a slut." It was still tempting to ruin her day by telling her the truth about yourself, but... at the very least you should wait until she's no longer balls-deep inside you. Time for another reminder. "Again, take that thing out of me!" Her anatomy was confusing, and troublesome as heck.

"Just be quiet for a few minutes, the uh... the bulge-thing shrinks on its own eventually." Her response was cold and uncaring, as expected. She wasn't particularly bothered by the fact that she had just **** herself on you, filled you with cum, and was still connected to your sore insides.

"I don't have a few minutes! There's sperm inside me!" It's stupid that you had to point out the obvious, but hey. A girl's gotta work with what she's got! Just before Gwen had a chance to respond, the two of you can hear the door downstairs loudly opening, and closing. New company arrived, as if your luck could get any worse...