A/N: This was written a while back for a "period challenge" on katarazuko on LJ. I'm just now getting around to posting some of these challenge fics on ffnet, and I hope you enjoy them! This one was particularly entertaining to write.

Warning: If the mention of a woman's menstrual cycle makes you uncomfortable, you may not want to read this one. Don't worry, it's not graphic, but the fic is centered around the issue.

Disclaimer: I don't own Avatar: The Last Airbender or any characters contained within. I do, however, own my plot and story so please don't plagiarize.

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In the beginning, Zuko had thought of all his companions as children. Even his Uncle seemed to have an overly young spirit. After only a few days of travel he began to slowly see them in a different light. Each of them showed their maturity in different ways…but none had been as disturbing or as surprising as Katara. He knew that she was old enough to be married by any nation's standards, but it had never really registered that such a crazy girl could be considered a woman.

That was until of course he had experienced the first day of her woman's cycle. He didn't have much experience with women, but he had learned enough from his lessons to recognize what it meant when he caught her washing bloody rags in the river after a week of no fighting. The blood had to of come from somewhere, and it definitely wasn't an injury. To Zuko's credit, for once in his life he had been able to put two and two together.

The cycle itself had only begun his thinking, but had not quite pushed him to fully considering her a woman. In fact for a few hours his only thoughts were about how anyone or anything could bleed for a week straight and not die, only to do it again the following month. It was creepy.

After his initial disgust he started to watch her carefully through the day. She was a little moodier but seemed more uncomfortable than anything else. Soon he found himself more interested in her condition than disturbed. Why did she want strange deserts? Why did she keep rubbing her back? What did Sokka mean when he had mumbled 'lucky for us this seems to be a light day'? Zuko wanted to ask her, but knew that he would only be made fun of. So, he kept on his usual grimace and tried to hide his fascination with something only a female could ever experience. Not that he would ever want to be female or experience it.

That night Katara slept farther away from the others. From what he gathered from the random comments (mostly from Sokka who received several water whips to the back of the head throughout the day) she tended to toss and turn a lot during her cycle; so she set herself aside so as not to bother anyone. As he stayed awake watching her roll back and forth he made the split decision to go and get a few of his questions answered. After all, she would probably be too tired to make fun of him and then just write it off as a dream the next morning…at least, that's what he hoped.

Carefully he crept over to her sleeping mat and crouched down beside her. "Katara?" Zuko whispered.

Katara mumbled a little before rubbing her eyes and looking up at him. He cringed on the inside thinking she looked far too awake for his hopes about her writing him off to come true.

"Zuko…can you heat your body up and lie against me?"

The question caught him so off guard that all he could manage was a few sputtered, "huh…?"

Katara had it in her to blush a little at her bluntness, but was far too uncomfortable to let this opportunity slip her by. "My body is really achy…especially my abdomen and lower back. Sokka is always a jerk about it and never lets me sleep near the fire even though the heat would help. If you could just put heat directly on me it would be even better than being near the fire."

Her pleading eyes, slightly pouted lip, and gentle blush reflected barely by the moonlight made his decision for him. Still a little embarrassed by the situation he awkwardly and stiffly brought his body down next to hers. He raised his body temperature slightly and heard her sigh happily. She then rolled over and grabbed his hand pulling him on his side against her back, and then put his same hand against her lower stomach. She then lifted herself up and pulled his other hand underneath her and around towards the first.

Through the process of her effectively using him as a blanket and putting herself in his arms Zuko could only dumbly let her manipulate their position. His brain had shut off the moment she had asked him to lay with her. His questions were forgotten, but his initial curiosity slowly began to get his brain running again. He decided to experiment a little, and heated up his hands more. This caused Katara to let out another happy sigh as well as snuggle into him more.

It wasn't until her soft butt rubbed into his crotch that he began to fully think of Katara as a woman.

She continued to grind against him, now only half awake, until her body was fully and tightly pressed against his. It didn't take long in reality, but to Zuko it had taken forever for her tiny body to finally fit into his form. Her wiggles and sighs were almost too much for him and when she was finished and sleeping soundly he felt equal parts relief, regret, and arousal.

He tried to think of other things, disgusting things to rid himself of his desire, but he couldn't get his mind off of her. Even thinking about her bleeding next to him didn't shake his arousal. It just made Zuko wonder what it would be like to go to bed next to her every night and provide heat for her when her body ached. He could hold her like this and she would sigh like he was the only one who could ever give her that much comfort. During her cycle she would praise his bending abilities and love him for being a firebender.

It should have scared Zuko have such foreign thoughts about the woman in his arms, but it didn't. For reasons beyond his thinking at the moment, it was comforting to think of them as lovers, husband and wife, Fire Lord and Lady.

On that thought, Zuko fell into the soundest sleep he'd ever had in his life.

…Which was good since as soon as Sokka woke up and found him sleeping cozy next to his sister with a certain straining and uncomfortable "boy problem", he was going to have one hell of a morning.

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A/N: Please R&R! And thank you to all my wonderful reviewers past and present! I love you all!