Take the pill, you can easily deal with minor changes

Considering the previous mystery **** did nothing more than slightly changing how your vagina functions, you figure that you can just take the pill and then seek out a pharmacy for a morning after pill. Beyond that, all you have to do is finding a hotel to stay at for a while and in two days from now you will be back to being a guy. Done, easy enough.
You're already looking forward to kicking your brother's butt for all the crap he put you through. He went way too far, just for the sake of getting some quick pussy. Perhaps after kicking his butt, you're gonna lock him into the basement for a day to give him at least an idea of what it's like to be stuck with something you dislike. Your petite fingers grab the small pill, and you bravely swallow it down under your mother's watchful eye and she immediately looks more relaxed and at ease. "Good girl! You're not even going to ask what it does? I'm surprised, and proud! You'll make a good addition to the family!" Hah, if only she knew. Your lazy brother will be back to being a single in no time. Hell, you will make sure that he will NEVER get a girlfriend again after this.

He was still sitting there by your side, waiting for you to give him a hand with his erection. Oh well, it's just a handjob. Reaching over, you grab his dick and begin stroking him while the three of you watch some random TV show. After a few minutes passed, your mom poked your side. "Looks ready to me." Glancing over to your bro, you see that he was fully hard, and looking at you with big puppy eyes. "It's about time to get on your back and spread 'em," she added, and you follow her instructions without delay, your head resting on her lap while your brother moved on top of you. Strange, it doesn't bother you anymore as much as it did a few minutes ago. Somehow you are confident that this should be annoying, but it's just sex. He already came inside of you twice anyway, one more time won't matter, and you can take the plan B pill tomorrow or something. "Looks like the medicine already kicked in, too," your mom comments while observing your behavior. Odd, you can't notice anything different...

In the meantime, your little brother positioned himself on top of you with his heavy weight, and pokes your labia a few times with his dick before sliding into your cunt with an audible squelch. Huh? You don't remember getting so wet... peering down, your genitals were swollen, wet and ready. Your mother gave you a kiss on your forehead. "Relax, dear. It's just the medicine. Keeps your pussy wet, and more importantly, prevents you from being all stressed out about tiny things." Neat.

There's an ongoing slippery noise while your brother thrusts in and out of your primed cunt, thoroughly enjoying this opportunity to fuck a girl again. The entire room had already begun to take on the scent of unprotected sex, a pungent mixture of your pussy juices and his sperm, an ample amount of both was caking your vulva.

"You two are making a great couple! Plenty of practice is a good way for you to help my son lasting longer in bed, too. You are helping each other out!" Her enthusiasm was awesome! It was making you feel great, too. Maybe you really worried too much, instead of just enjoying this unique opportunity?

Instead of struggling or being mean, you spread your legs further apart which allows him to have even more fun pushing painfully deep into you, repeatedly bashing his cockhead against your sensitive cervix. But it didn't matter as long as he was enjoying it, right? There's a familiar throbbing inside your pussy soon after, and you look back up to your mom who gives you a reassuring smile. "Isn't that so much better? Simply relaxing and fulfilling your purpose?" Yeah, it kinda was. What are the odds of getting pregnant, anyway? Wasn't it something that took, like, months or years of trying? Yeah, it's fine...

Jimmy rolls off you and you can finally inhale properly again. While you've still got your legs spread, your mother reaches over to your crotch... and suddenly plunges two of her fingers into your sore slit, coaxing a gasp and an unsure expression out of you. "Just another trick I can teach you, honey. If you like a bit of risk, here's another thing you can do..."
She suddenly slides her fingers in deep, shoving your brother's sperm all the way inside and against your cervix. "Like so!" However instead of pulling her digits back out, you became somewhat aware of her... beginning to caress and massage your cervix, with the tip of her cum-covered finger. "W-what are you doing?" you ask with what little confidence you could muster. "Just giving my grandchildren a slightly better starting position." As sensitive as things are in there, you feel her scooping up a good amount of your little brother's semen with her fingernail, pushing the thin nail gently through the tiny opening of your cervix and then depositing the goop halfway. "There, now it's all up to your boyfriend's happy swimmers!" Oh... well... that probably means you have to care even less about being careful.

After finally pulling her fingers back out, she wipes them clean on your tummy and places the previous box of pills on the nearby table. "Since they're helping you relax, feel free to take more whenever you want! I want my son to have a happy girlfriend!" It was nice to feel at ease, but you were losing control of yourself. On the other hand, giving up control is what makes it so relaxing... you didn't worry about responsibilities as much. Taking one more pill may not make a difference, or it could make all the difference...