I don't own Yu Yu Hakusho. This takes place after the series finale.

Chapter One- Ice Apparition Secret

Hiei listened as Yukina related another story from her youth. He enjoyed listening and spending time with his sister. He had been content with never telling her that he was her brother but a visit a few weeks back negated that. He had dropped by just to see her and she had prepared the usual tea and sandwiches. He had waited for her to ask about her brother as she usually did as she didn't believe he was dead but this time, she had asked a different question, though related to her usual inquiry.

"Hiei, you're my brother, aren't you?" she had asked.

Hiei had kept his face neutral as he said, "What makes you say that?"

"Well, everything I know about my brother fits you. You're the same age, both fire demons, and the same eye color to match mine. Also, you visit me like a brother would visit a sister." Her eyes shone with hope. "Please tell me the truth. Are you my brother?"

Hiei had shifted a little before exhaling and saying, "Yes. I am your brother. I had reasons for not telling you," he had added quickly in anticipation of her next question.

"What reasons?"

"I had asked a surgeon for my Jagan to find the village and the stone that I had recently lost. He agreed after hearing my life story and told me that the price was that I could not tell you we were related. During my first six months upon returning to Demon World, I encountered the surgeon and he claimed if I could defeat him, he would release me from his price."

"And you won," Yukina had cut in. "Otherwise, you would not be telling me."

"Actually, it was a tie, but he released me anyway."

"And the other reasons?"

"I…didn't think you'd be happy having a criminal for a brother. I know that's a weak excuse when I thought back on it."

"Yes, but your promise made sense. I'm glad you finally told me."

I'm glad I told her, too, he thought as Yukina finished her story.

"Hiei, could you tell me about your childhood?"

"There's not much to say. They are pretty much the same."

"I don't care. Tell me one."

Hiei recoiled slightly at the harsh tone from Yukina and the hardness of her eyes. "Yukina," he said in a softer tone than he usually spoke and was surprised by how…gentle it sounded.

Yukina blinked and sat back with worry and fear. "Oh, dear," she said. "It's happening."

"What's happening?"

"Every ice apparition goes through a brief period where she becomes a man. It starts in adolescence and occurs once every fifteen years. Rui told me about it but I haven't gone through it yet."

"A man?" Hiei repeated. "How brief a period?"

"A day or two. Hiei, you do have ice apparition blood in you so that means you'll be female briefly."

"I…will?" he asked faintly. "When?"

"Very soon. My tone is a warning to me."

"Your eyes had hardened briefly also," Hiei noted.

"Oh!" Yukina got to her feet and hurried away, confusing Hiei. After several minutes, she returned, wearing pants and a shirt tucked into it. She smiled as she sat down. "Now, I'm ready."

Both siblings felt a feeling in their stomachs; a burning one for Yukina and a chilly one for Hiei. He shivered a little as the chill spread outward. He heard Yukina moan, her voice sounding lower meaning they were feeling their changes in gender. He gasped in a higher voice as the chill spread even faster. He felt his blood cool and his body altering into a different shape. The chilly feeling abruptly ended and Hiei looked down to see a female body, the shirt untucked to accommodate her breasts. She looked up at Yukina and almost didn't recognize her twin.

Well, actually she did. The hair remained the same and the eyes were still red just not as wide or soft. His face were angles instead of curves. His chest was flat and solid muscles were over his torso and limbs.

"Hiei," Yukina said in a tenor voice. "You're lovely."

Hiei chose to take his word for it and replied, "And you are handsome," in a higher voice, somewhere between alto and soprano.

Yukina nodded in accepting his sister's words. He lifted a hand to examine it. "Considering our race become male for a brief time, it definitely makes it wrong for them to banish you."

"Perhaps, to them, they weren't really male, despite their bodies," Hiei suggested.

Yukina lowered his hand. "Yes. That makes sense." His eyes quickly looked Hiei up and down. Her body had lost some muscle, but there was no denying the strength she still had. Her eyes were wide and soft with a gentle curved face. Her breasts were small and her torso was slender. The bandages around her fingers and arms were loose which exposed some of her dragon tattoo on her right arm. Her pants were loose around the waist but the hips kept them in place. "Hiei, you're welcome to stay until you're male again."

She nodded and said with relief, "Thank you. I don't want anyone else to see me right now."

Yukina nodded in understanding. He didn't want anyone to see him either. My first change to male and I feel…embarrassed. Funny. One would think I would be less emotional but then again, it's only my body that's changed, not my mind. Although, I may experience male tendencies later on as I have just changed.

Hiei tightened her belt to keep her pants from slipping down. She felt grateful that she had hips to keep her pants from completely falling down. She then tucked her shirt in to keep her breasts from moving too much. They put a little weight on her chest that felt uncomfortable and was glad that it would only be one or two days every fifteen years. I can keep coming here to change and no one will ever know about this, except Yukina. I would like some guidance in being female and more about this gender switch.

"Yukina, did Rui tell you anything else about this change?"

"Yes. She said that no one acted violent or cruel in her male state but did act like a man due to some hormones as that is related to the body. The mind remains unchanged. I have seen Rui change once which was how I learned about this."

"So, we'll act like our current gender because of hormones, but still think as usual."

Yukina nodded and held up a hand palm up. A puff of ice plumed up briefly. "Still ice. I would have thought with you being my twin, I would have fire powers while male."

"That is an interesting thought." Hiei held her hand up, focused, and a ball of ice appeared. Hiei blinked before dissolving the ball. "Ice. Why do I have ice powers?"

"You are female right now. Perhaps, the fire is tied to your male form."

"And since you have never used fire, your powers are still ice."

Yukina silently agreed with her and wondered how he would act when his hormones surfaced. This will be an interesting experience.