Despite how much I wanted this, I was still nervous as I held the first vial in my hand. The contents looked almost like blood, but the red was a little too bright and it flowed a little too easily.

"What will it taste like?" I asked. "And what will it feel like?"

My sister replied, "They all taste good, don't worry about that."

I nodded slightly, "All right. Um... How long will it take? And what's each step do?"

She replied, "The whole entire process could be over as quickly as five or six hours, or it might not be done until some time tomorrow. Each step has to be completed before the next one starts, and how long those steps take will vary. To a certain degree, it is up to you."

"Ok," I said with a frown. "So what does each potion do?"

Cat explained, "With one exception, the potions all have multiple effects. You know how much I like surprises, and I seem to recall you enjoy them too so I'd rather not spoil everything in advance. But..."

Her expression became serious as she looked me in the eyes and stated, "When I told you a few minutes ago that as my apprentice you'd have to obey me, you'd have to do what I said, I meant that literally. This first potion has a few effects, one of which is a necessary precursor for the next potion. But another is what we call Limited Obedience. It will make you more inclined to do what I say, should I give you a direct order."

For a moment I thought she was kidding, but the look in her eyes told me she wasn't. I frowned, "Why?"

Cathryn grimaced, "The faculty at the academy had ways of ensuring we students did what they told us, I don't have those means here. And as my apprentice and student there's things I'll be asking you to do that you may not enjoy."

She continued, "Limited Obedience won't take away your free will or make you my slave, I would never do anything like that. Not to you, not to anyone. And it doesn't force you to obey my every whim. It simply makes you more inclined to follow my direct orders, nothing more. If you really don't want to do something, or if something's outside your nature, you can always refuse."

I hesitated as I looked from her down at the vial in my hand, then back up at her again. I took a few moments to think about what she was saying, but in the end it wasn't that hard to decide. "I love and trust you Cathryn, and I know you love me too. And I want this."

Cat smiled, "I promise I won't let you down. So whenever you're ready? The process will begin once you drink that first potion, little sister."

Hearing those last two words sent a flutter of nervous excitement through my body. I was her little sister, and perhaps by tomorrow morning I'd actually look the part.

My attention returned to the vial as I twisted the cork. The wax seal broke and the stopper came free, then before I could hesitate again I tipped the contents up into my mouth.

The taste was surprisingly agreeable. It was like sweet cherries, with a hint of ginger. Just enough to leave a slightly warm tingling after-taste in my mouth.

Cathryn smiled as she gently took the empty vial from me and put the stopper back in, then she placed it back in the case. "These vials don't come cheap, and now that money is an issue we need to recycle. So we won't be dropping or breaking any of them."

"Of course," I nodded. "Good point."

My heart continued to race as I sat there across from her, and I anxiously waited to feel something. I kept glancing down at myself, my hands mostly as I left them resting on the table.

My sister got to her feet. She picked up the two cups we used earlier and poured us more wine, then before sitting down she pulled the second chair around so she could sit beside me.

She handed me my cup and had a sip of her own, then said "Just relax sister. Try not to be so anxious? Relax, think happy thoughts about what your new life will be like. This time tomorrow, you'll be my little sister, my apprentice."

I sipped my wine as I tried to follow her instructions.

"What do you think I'll look like as a girl?" I asked. "Will the magic make my hair longer, or will I have to wait for it to grow out? Will I... Do you think I'll be pretty?"

Cathryn smiled, "I think you'll be adorable. Have you picked your new name yet? You'll note I've not been using the old one, it's certainly not appropriate for a girl like you."

My heart fluttered at her words and I blushed, "I haven't. You know I've put this out of my mind since I was twelve? I didn't dare think of it after how dad was back then."

"Since you haven't chosen one," she decided with a smirk, "I get to choose for you. You shall be Valeria."

"Wait what?" I frowned. "No, I just need a few minutes to think of something."

Cathryn laughed, "Nonsense. I've already named you. Now tell me Valeria, how are you feeling?"

I blushed but there was another flutter deep inside. Could I really be Valeria? It sounded a little too posh for me. Then again, if I was going to become an alchemist someday, perhaps it would fit after all?

As for how I felt...

"I feel happy," I replied with a smile. "And kind of warm? I know it's late spring, but it feels like the middle of summer. I feel a bit sweaty, like it's too hot in here. Except I know it's not that warm, we don't have enough firewood to keep the stove burning all day long."

"That's all right Valeria," my sister replied. "Finish your wine, the drink might help you cool down a bit."

I nodded and gulped down the contents of my cup.

Instead of cooling me down I only felt hotter. It was like a hot August afternoon and I was tempted to peel off my clothes to try and cool off a bit. Then with a shock I realized I was also horny, and to my dismay there was an obvious tent forming in my trousers.

"Are you ok Valeria?" Cathryn asked again. "You look a little troubled."

I turned towards her and just stared for a few seconds as I was suddenly captivated by her beauty.

Cathryn had always been pretty. I'd spent most of my life secretly envious of her looks. The past five or six years I'd also secretly lusted after her.

She was tall, slim, she'd been blessed with beautiful straw-blonde hair, fair skin, and bright blue eyes that seemed to sparkle in the fading light. Her lips were full and pink, and she was smiling slightly as she watched me.

My eyes drifted downwards and I took in the contour of her dress as it clung to the swell of her chest. She was well-endowed, same with our mother. The women of our family tended to be curvy, though in Cathryn's case her height lessened the effect somewhat.

For a few seconds I was lost in some lewd fantasies as I stared at my beautiful sister's chest, especially the little glimpse of cleavage revealed by the deep neckline of her dress.

"It's another effect of the potion little sister," Cathryn explained. "No need to be embarrassed. It's preparing your body for the process, but as that happens it's also made you very aroused."

"Oh," I gulped. I felt like my cheeks were on fire again as I stared at the table.

My heart was pounding in my chest and after a few seconds I asked, "How long till it goes away?"

She replied softly, "It won't, until we take care of it. Now why don't you get out of those boys clothes Valeria? You won't be wearing that sort of thing ever again. And anyways, those trousers look uncomfortable on you right now."

My eyes widened as I almost didn't believe my ears. "What?"

"Come on," she said as she got to her feet and started to help me undress.

I was almost too surprised to respond as she pulled my shirt up and off, then she had me get up and she loosened my pants then slid them down off me. Suddenly freed, my penis stood out tall and proud and hard, which made me grimace. As much as I regretted the thing, it felt needy. And thanks to what I could only assume was the potion's effects, I was almost ready to give it what it wanted.

My right hand drifted closer to my groin, but Cathryn shook her head "Not yet little sister. It's time for your next potion my dear."

She handed me the vial of bright pink liquid, and as I opened it she told me "You're ready now Valeria. This is the potion which will reshape your body into the feminine figure you desire."

That was all I needed to hear, and I eagerly gulped it down. It was a sweet syrupy liquid, that tasted of strawberries.

Cathryn took the vial back and replaced it in the box, then she picked up the one with the watery blue contents. "You just need one final catalyst to initiate the transformation, which I'll provide very soon."

I was expecting her to hand me the third vial, but instead she opened it and drank it down herself. The empty glass vessel went into the box, and she closed the lid and set the latch.

Then she smiled at me and took my hand in hers, "Come sister. Let's get things started."

She led me into the bedroom and had me lie down on my bed. I was naked, my body was hot, my heart racing, and that thing between my legs was straining for attention. I was having a hard time not touching myself, and an even harder time not looking at Cathryn.

Then to my shock she pulled off her dress and tossed it onto the other bed. She had nothing on beneath, and I found myself staring at my beautiful sister. The sight of her naked body was more than I could take in my current state. I was too horny to even try to understand what was happening as Cathryn climbed onto the bed and straddled my waist.

With another shock I realized she was already wet, I could feel her arousal as her vulva pressed against my abdomen.

She was smiling as she commented, "I'll bet you're still a virgin little sister. Unfortunately I'm going to have to take that. We need to do this to trigger your transformation, so just relax and think about how pretty you'll be when you wake up."

Without waiting for a response she repositioned herself, then slid down onto my shaft.

She was right, I was a virgin. As much as I was attracted to girls I never had the confidence to approach any of them. And my feelings towards my own body meant I'd likely have been unable to do anything with a girl even if I did get close to someone.

The potion took care of that though, I was too horny to care about much of anything at that point. All that mattered was the need for release, and the incredible sensations my sister was giving me.

I felt her hands on mine, and she guided them up to her chest. I'd fantasized about such things, but I'd never actually touched a woman before. The warm yielding weight of her chest in my hands felt nice, and she reacted with little gasps of pleasure as my fingers brushed and caressed her thick pink nipples.

Her hands moved to my own chest, which was still sadly flat and muscular, but there were some small sparks of pleasure as her fingers touched my own small nipples.

In between moans as she rode up and down on my shaft she gave me words of encouragement. She reminded me how I would soon be an adorable girl, that this was a necessary part of the process, and she promised that I'd be very happy with the results when my transformation was complete.

I could hear her and understand what she was saying, but I wasn't able to respond in any coherent way. My lust, my need was too great, and the sensations she was giving me were too overwhelming. The best I could do was nodd slightly between my own heated moans and gasps.

Time seemed to lose all meaning, I couldn't tell if we'd been at it for one minute or twenty. All I knew was I felt like I couldn't go on much longer, and Cathryn seemed to know that too. The movements of her body became faster, and rougher. She was lifting herself up then ramming herself back down on my rock-hard shaft, and with each thrust I felt the pressure build inside me.

I was also aware of the tension growing within her. Her internal muscles seemed to twitch and tighten around me as she let out a louder moan. That was it for me as well, and my own loud cry of pleasure joined hers as my body twitched and spasmed. I felt myself unload deep inside her in several strong spurts.

For a moment afterwards I panicked about what could happen if she were to become pregnant, before I remembered she said she knew ways to prevent that. I trusted my sister to take precautions and look after herself that way. She'd obviously planned everything well, she wouldn't have overlooked that detail.

I finally slumped back on my bed, sweaty and spent. My arms splayed out to the sides and I was panting hard, but it felt like the arousal that had been burning inside me had been satisfied.

"Good girl," Cathryn whispered, and the words sent another flutter through my body.

I was definitely going to talk to her about all of this, but a wave of weariness passed over me and I decided that conversation would wait till later.

My eyes drifted shut as I felt her leave me. I heard her move to the other bed, but I was asleep before she even lay down.

PurpleCatGirl

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