Sister Knows Best: A Magical Gender Bender Maternity Tale (Note: I understand that the prompt describes a non-consensual sexual encounter, which is not acceptable in real life and not depicted here in a humorous or erotic way. The title I provided is meant to be a darkly comedic and over-the-top take on the given plot, and not an endorsement of the actions described.)

I woke up in the middle of the night, my body feeling strange and different. I looked over at my sister, who was sleeping peacefully, her chest rising and falling in the soft glow of the moonlight. I rubbed my eyes, wondering if I was still dreaming.

As I got out of bed and padded over to the mirror, my heart began to race. I was shocked to see that I was starting to transform into a little girl. My flat chest had become small and round, and my hips had widened. I looked down at my hands, which had become small and delicate.

"Oh my god," I whispered to myself. "What is happening to me?"

My sister woke up with a start, her eyes flying open. She saw me standing in front of the mirror, my body changing before her very eyes.

"Wow, look at you!" she exclaimed, a huge smile spreading across her face. "I always wanted a little sister."

I turned to her, my eyes wide with fear. "What is happening to me?" I asked again, my voice shaking.

She got out of bed and walked over to me, her eyes filled with excitement. "It's a long story, but the short version is that I'm a transgender woman," she said. "I've been taking hormones to transition, and I must have accidentally given you some."

I stared at her in shock. "So, I'm going to become a woman?" I asked.

She nodded. "Yes, you will continue to transform, and eventually, you will become a woman."

I started to panic. "What will people think? What will they say?"

She put a hand on my shoulder. "Don't worry, we'll figure it out together. I'll always love you, no matter what."

I started to cry, feeling overwhelmed by everything. She hugged me, whispering soothing words in my ear.

"Will I still be your brother?" I asked, sniffling.

She smiled. "You will always be my brother, but now, you will also be my sister."

"Will you still protect me?" I asked, looking up at her with tears in my eyes.

"I will always protect you," she said, her voice firm. "Now more than ever."

"Will you still play with me?" I asked, my bottom lip quivering.

"Of course, I will always play with you," she said. "But I might have to carry you sometimes."

I smiled through my tears. "Will you still teach me things?"

"I will always teach you things," she said. "But you might have to learn some new things too."

I looked up at her, feeling a sense of peace wash over me. "Will you still be my best friend?"

She hugged me tighter. "I will always be your best friend, now and forever."

The transformation had begun, and I knew that I was not alone. With my sister by my side, I knew that I could face anything.