Sadly, I do not own Sailor Moon or InuYasha, sooooooo there's that.

Chapter 1 The discovery

Though Usagi and Mamoru supposedly had been lovers in their previous life, they never could get the chemistry going for it in this new life. Not that he wasn't a great friend, but there were days when he annoyed the shit out of her with all his long winded speeches while a youma prepared to attack them. When he had announced to her that he had decided to leave for America in preparation for his medical degree, while she was sorry to see her friend go she was not sorry to be rid of Tuxedo Kamen. Fighting all alone had been a bit of adjustment for her though, and Luna helped from the command center where she could. It was after one of these fights, that the change happened.

The Youma had been defeated, but barely, when Sailor Moon doubled over in pain and she fell to the ground. Her eyesight became so sharp it hurt, so she closed them. Her ears! What had happened to her ears? Because of being a Lunarian her hearing had already taken some getting use to, but this threw her control out of the water. She could not focus on a single sound, and so it threatened to overwhelm her. It was when she cracked her eyes open, to take a look at her hands, that panic began to set in her. They were becoming elongated and sharp at the fingertips, everything had become elongated. Each breath was a struggle to take, every bone hurt.

With what strength she had left, she teleported herself back inside of the command center. She heard Luna shouting, but Usagi had finally reached her limits. She passed out, and detransformed from Sailor Moon back to Usagi. What she did not know is that the change had not been taken away with it. Usagi woke up some time later, still gasping for breath and shaking. At least her eyesight was coming back into shaky focus. Thank God for small miracles.

"Luna...What the hell happened?" She asked, trying to keep her voice even. Her anger still got through though.

"I'm not sure why this is occurring now. When you became Princess Serenity, a change began to take place in your DNA, replacing your human DNA with lunarian. It seems that your human DNA was hiding a dormant demon gene, and it activated. It wasn't detected before, but it seems to have fought back with a vengeance. Both your Lunarian DNA and Demon DNA are slowly mingling with each other now that the Demon part has awoken." Luna explained.

"Are you telling me that I've regressed into some kind of full fledged LUNARIAN DEMON?!" Usagi shouted, angrily. "Regression doesn't happen this late! It's like demon puberty or something, isn't it?"

"I don't know. I have no experience to fall back on for this." Luna said, clearly worried about her charge. "I don't know that there have ever been lunarian demons before."

"I think...I know of someone, but I'm going to break a lot of rules you're not gonna like and right now I don't care." Usagi growled, shaking as she reached for her cell phone and called a friend. "Kagome? Hey, Kagome. I need your help, but I have a lot of truth bombs to lay on you first okay?"

"Sure thing. I'm at home, so no worries about this being overheard." Kagome replied. Usagi was her friend, but she never called for help unless it was big. "I'm sitting down and everything."

"Good. First truth bomb; I am Sailor Moon." She hears a crash, like glass breaking, but doesn't stop. "Second truth bomb; Luna is my talking cat that runs the command center to coordinate with the other Senshi. Third truth bomb; I am Princess Serenity, and that leads me to my final and kind of obvious Fourth truth bomb; I am not human, I am Lunarian. How are we doing so far?"

"Oh...Oh, Usagi! When you said truth bombs I was thinking something less atomic, ya know?" Kagome shrieked.

"Full sentences. We're doing good then. Kagome, you're the only friend I have who is in a relationship with a demon. I know he's only half, but I need help." Usagi exclaimed. It was getting hard to breath again.

"I don't understand. How can he help you? You want him to fight, like be a new partner or something?" Kagome asked. "You're breathing heavy, do you need a doctor?"

"No, I need a demon...I need someone...to tell me what to do...I don't understand...what's happening to me..." Usagi struggled to control the anger in her voice, as being in pain brought it out more. "It seems...somewhere down the line...my family has demon DNA...and it not only...woke up...it took over...with a vengeance...I think...I've regressed...into some kind of...full fledged...Lunarian Demon."

"Usagi..." Kagome was trying to come to terms with what she was being told.

"Are you...still home?" Usagi asked, trying to stand.

"Yes..."

"Alright, I'm teleporting over... I think that's all ...I'll have strength for...before I pass out again...Please don't freak out." Usagi said, and hung up the phone.

She phased over to Kagome's bedroom, barely standing now. Kagome sat in her desk chair, mouth hung open but no words coming out. She saw the eyes, the ears, the hands, and just how much taller her friend seemed than before. Usagi looked up from her hands, a blank look on her face. Thank goodness Kagome stood up in time, as Usagi passed out having used the last of her strength.

Usagi woke up to find Kagome standing over her, dabbing a wet wash rag to her forehead. Why did she feel so warm? Why was she still shaking? How long had she been like this? She turned her head, and saw Kagome's boyfriend Inu Yasha just staring at her. It made her feel slightly irritated, though she supposed the fever was doing that too. Usagi had always had a foul temper when sick.

"Kagome explained everything. I've asked my brother if he's ever heard of a regression like this, not giving a lot of details to him, but he hasn't heard of anything like you. I wasn't sure how much of this you wanted to keep to yourself. We can help you through it, but then we need to figure out how it happened in the first place. It's not reversible, but it will give you answers, maybe make this easier." He said, arms crossed in front of him like he almost didn't want to be there.

"Thank you. You must be Inu Yasha. Kagome speaks highly of you." Usagi said, grateful for any help, and noticed he visibly relaxed.

"Inu Yasha is used to his full demon brother Sesshomaru and his harsh behavior." Kagome explained.

"Oh, well I haven't been a full demon for very long. Give me a few days, I'm sure the snobbery will come to me in no time." Usagi said grinning. She tried sitting up a bit. "Is there any water?"

"Here." Inu Yasha said, getting the water for her.

"Thank you again. You two are so kind. I'm sorry for all the truth bombs, Kagome. You were the only one I thought could handle it, out of the friends I have, considering you deal with demons on a regular basis." Usagi explained, as she tried to get out of bed. "I need to see..."

She made it a few steps before nearly collapsing into the desk. Kagome and Inu Yasha helped her the rest of the way.

"This is so embarrassing. I can't even walk to the bathroom mirror without falling like a newborn calf." Usagi growled. "You two really are the best."

The first thing she noticed was the upturned golden crescent moon. It had not gone away as it normally had when she returned to normal. She was taller, she could tell. Her hands she could accept. That wasn't so bad really. She looked down at her bare feet, and saw they were the same. Her eyes though, her pupils no longer resembled a humans, but were slits instead. She could not stop herself from touching her now very demon looking ears, looking over to Inu Yasha with worry. Hers seemed humanish enough, but very pointed. Her hair, though blonde, had begun to turn to a kind of silverish blonde, and she wondered how long it would be until it was all silver.

"Wait...is that a tail? I have a tail?! She shrieked, hurting her own ears, as well as Inu Yasha. "So, I'm some kind of a lunar dog demon?"