Alchemist’s Apprentice

*** content warning: lactation, sex ***

I drifted awake with a little smile on my face.

As usual my sister and I were cuddled up together in bed, and it felt really nice to wake in her arms each morning. There was a single thin sheet draped sideways across us but it didn't cover much, our legs, arms, and chests were bare. The warmth potion Cat drank the day before was obviously working, she was quite comfortable sleeping without any blankets overtop of us.

Cathryn was quiet as she lay behind me, her body pressed tight to mine. I could feel her breasts against my back, and her cock touching my behind and lower back. I also felt the now-familiar heavy pressure in my chest, and I knew we'd have to do something about that before we did anything else this morning.

That made me smile as well. It took me a week or so to get used to it, but my sister wasn't lying when she said it would be enjoyable. And having her take care of it for me made the process that much better. The fact that it almost always led to more fun together before we began our day didn't hurt either.

And that's what I was hoping for again this morning.

I was already getting excited just thinking about it, eager for the two of us to get started. I snuggled myself a little closer against my sister, wiggling my behind and shoulders so they rubbed against her shaft and chest.

She was probably already awake, as she responded almost immediately. Her hands moved to cup my boobs, while I also felt her cock stir and harden as it pressed a little more noticeably against my backside.

"I take it you're awake?" Cat whispered in my ear.

"Good morning Cathryn," I whispered back with a smile. "I'm awake, and I need your help again."

Her hands gave my boobs a gentle squeeze, getting a soft moan out of me. She sounded amused as she responded, "Yes, you do feel rather full now."

Despite saying that, she didn't make any move to help. She didn't even get up out of bed, she just continued laying behind me, with her hands on my chest.

After another minute or two I finally asked, "So um... Are we going to do something about that? Or not?"

"Maybe I'm waiting for you to ask nicely?" she teased, and I could practically hear the grin on her face.

I rolled my eyes and teased back, "Would you like me to beg?"

Cat was silent for a second or two, and when she finally answered she sounded a little taken aback. "I wasn't really looking for that Val, but um... Actually it might be kind of fun? As long as it doesn't bother you."

The whole thing felt a bit silly to me but it didn't bother me so I decided to play along with her. In fact I did my best to play it up for her.

I tried to sound desperate, needy, horny, and vulnerable as I pleaded softly, "Oh Cathryn, my boobs are so heavy and swollen! And you know how sensitive they get when they're like this? Won't you please milk them for me? You're so much better at it than I am. Please sis, I'm begging you!"

Apparently my little act had a stronger effect on her than I was expecting. By the time I was done her hands were gripping my breasts a little tighter, while it felt like her cock was fully erect and pressing into my back a little more firmly. And finally her breathing had grown heavy in my ear.

"Ok wow," she half-whispered. "That's uh... Yeah I'll help."

It took all my willpower not to giggle at how flustered she sounded. Normally I was the one who got all shy and embarrassed. As much as I preferred having her do this for me, it still made me blush every single time.

After another couple seconds she finally let go and got out of bed, then practically ran to go grab a bottle. Meanwhile I grabbed one of our towels just in case, then got into position on the bed.

She returned with the bottle while I kneeled on the bed. As usual I leaned forward a bit, so my chest was kind of thrust out at her. My amusement was quickly replaced by excited flutters in my stomach while my cheeks went red again.

Cat stood in front of me but she didn't start yet. Her eyes slowly went up and down over my body, then she gulped and asked "If it's ok, would you mind um, asking again?"

It was a lot harder to do the silly acting while we were facing each other, but her slightly shy, timid way of asking helped. If she'd been more forceful or demanding I probably wouldn't have been able to do it.

So I gulped and tried again. I didn't look her in the eyes, even though that mostly meant looking at her chest or her rock-hard cock. I picked the cock and fixed my eyes on her shaft. And with my cheeks growing brighter red I put on my shy timid horny vulnerable act again, except this time I wasn't entirely acting for some of those emotions.

"Mistress alchemist," I began in a soft pleading voice. I figured giving her a title might make it a little more fun. "My boobs are so heavy and sensitive, and my nipples long for the touch of your soft skilled fingers. Your poor assistant needs your help. Won't you please milk me? I'm begging you!"

By the time I was done I felt like I was blushing all the way down to my chest. I stole a quick glance up at her and realized she was blushing just as hard. But where I only took a brief peek at her, she was staring intently at me. And the look of lust in her eyes was pretty strong.

"Damn Val," she finally responded in her own quiet voice. "You're way too good at that..."

Her words made me blush hard enough I almost worried about my cheeks catching fire as I waited for her to get started. Fortunately she didn't keep me waiting that much longer, just another second or two before she moved into position before me.

Then her right hand got to work on my left boob, and the sensation of those skilled fingers of hers pinching, pulling, squeezing and kneading my teat was the perfect reward for my little performance. Each squeeze and pull sent another thick stream of rich creamy milk into the bottle, while also launching sparks of pleasure up and down my body. Both my nipples were rock-hard, while my labia glistened and my clit throbbed.

As usual I didn't even notice when she finished with the left and started on the right, the sensations all just sort of blurred together in a way that left me a happy needy dripping mess.

When she finally finished, Cathryn placed the bottle ontop of our dresser. I noticed there seemed to be less this morning, usually I filled the bottle right to the top but today it was only about three quarters full. I didn't bother asking about it though, there were much more important things on my mind as my sister returned to stand directly before me.

She was every bit as worked up as I was at that point, and the musky heady aroma from the pre dribbling down her shaft set my mouth watering. I licked my lips then glanced up at her to see if she wanted the same thing I did.

That look of lust was still present in my sister's eyes, but this time she shook her head slightly. She had something else in mind.

Cat took a deep breath and asked, "I'd like to try something new today Val, if it's ok with you. Now that you've had the contraceptive potion..."

I felt a mix of shock and excitement and my eyes widened slightly. A dozen thoughts and feelings raced through my mind and my heart as her words and all their implications sank in. It only took a moment or two, as I quickly determined that I wouldn't want a guy inside me like that, but it was different when it was my sister.

And I'd be lying if I said I hadn't thought about doing that with her, pretty much every single day since the moment I first saw her long thick cock standing up between her tall shapely legs.

"Ok Cathryn," I replied softly. "I've been looking forward to this. Um, obviously I have no idea what to do though so you'll have to guide me?"

I had no doubt she'd been thinking about this for as long as I had, probably fantasizing about it and planning it. Not to mention she was just that much more experienced, after three years at that perverted school. Her eyes went up and down over my body again and it almost felt like she was a predator sizing up her prey.

Meanwhile I had it all on display for her, I was still kneeling on our bed with my knees apart and my chest thrust forward.

"I had all these ideas on how to make this really special," she admitted. "But I don't think either of us needs any more foreplay now. I just want to ravish you."

That set my heart racing and sent shivers of nervous excitement through me. The best response I could muster was a simple, "Ok."

And that was all my sister needed to hear. With a few hurried words she instructed me to turn around. I was on my hands as well as knees, and facing away from her. Despite my inexperience I knew what was coming, and I strained to look back over my shoulder in anticipation.

Cathryn stood behind me, and that look of lust in her eyes was even stronger now. Her fingers touched both my thighs, then ran up and over my behind as she positioned herself and moved closer.

Then I felt the tip as it pressed against my soaked labia. I let out a soft gasp as my hands slowly gathered up some of the bedsheets in clenched fists.

My sister's hands softly caressed their way over to my hips, where she held me in a firm grasp as she started pressing herself harder against my lower lips.

I gasped again as my lips parted and she began to enter me. In some ways it wasn't that new, in the past few weeks I'd had my fingers and hers in there up to the knuckles. This wasn't like fingers though, her cock was a lot longer and a lot thicker.

There were a few little shocks of pain as she stretched me, but that was mostly outweighed by the pleasure of her hot throbbing shaft sliding between my wet sensitive lips. I actually had some doubts about how much of it she'd be able to get inside me and whether or not it would hurt when she hit the limit.

Except that didn't happen. And to my shock I finally felt her thighs pressing against my behind, meaning she had her massive cock fully buried inside my hungry slit.

Somewhere in the back of my mind I realized that had to be another effect of one of the many potions she'd fed me, either yesterday or three weeks ago. As soon as I had the thought I promptly forgot it again, there were more important things to pay attention to at the moment.

After a brief pause to let me get accustomed to feeling so very full, my sister started to slowly withdraw again. A long low moan escaped my lips as her hard throbbing cock gradually pulled free of my lower lips, and that feeling of fullness was replaced with a sense of emptiness.

Fortunately she didn't leave me empty for long. Only a second or two later she pushed her way back in, a little quicker this time. And as she held herself deep within me, Cat leaned forward slightly and asked "Are you ready little sister?"

I was still gripping the bedsheets in my fists and my head was bowed down slightly, my eyes closed as I focused on nothing but the sensation of her shaft deep inside me. I could hear the lust in her voice, and it was mirrored in my own as I nodded "Very ready. Please Cat, don't stop this time?"

Her hands squeezed my hips as she pushed a little deeper into me, then pulled almost all the way out before thrusting back in again. Once again it was nothing like doing it with fingers. There was no comparison, the length and girth, the heat, the shape, everything just made it so much better.

My boobs started to jiggle and bounce as my body moved each time she buried her cock deep inside me. Every stroke of her rock-hard girldick was answered with a short gasping moan from my lips, and every thrust drove me another step closer to climax.

The sound of Cathryn's hips slapping my ass as she pumped in and out of me only added to the experience, along with the soft grunts she was making as her own orgasm neared.

She picked up the pace, her movements became quicker and more demanding as her muscles grew taut and her hands gripped my hips even tighter. Meanwhile I was starting to move with the tempo, pushing myself back every time she thrust forward.

Cat reached her peak first. With a sound like a hungry growl she plunged her large shaft as deep as she could get inside my pussy. I felt her muscles spasm, and her first spurts of hot come coated my insides.

That was all it took to push me over the edge, my brain flooded with white-hot bliss as I let out a happy scream. My body quivered and shook while my internal muscles gripped and squeezed my sister's cock, milking her for every last drop like she'd milked me earlier.

She was clutching my hips so tightly I'd probably find bruises later, but in the moment all I cared about were the sensations I was getting from her glorious shaft. Cat pumped in and out of me a few more times before she was finally spent, and the two of us slowly settled down onto the bed together.

We ended up laying on our sides, my sister was once more pressed against my back as though we'd only just woken up. Except her penis was still buried deep in my pussy instead of pressing against my back, and both of us were coated with a thin sheen of sweat.

I felt her gradually soften inside me as we lay there, both of us panting, both of us basking in the happy post-sex bliss.