A/N: Ok so this is my first Percy Jackson fanfic with my OC Attalanta. She is Percy's twin sister and was taken away at 6 years old. Everyone thinks she's dead and only Nico knows about her. I will make a one shot about that latter. Anyways I think this is the First one like this. On with the story.

Disclaimer: I do not PJO or HoH. All charecters except for Attalanta and her Family belong to Rick Riordon.

Prolog

I woke up to my sister yelling. Another day in paradise. I thought. I'm 12 years old. I have blonde hair and blue eyes. I am usually tagged as an idiot because I act like that. Why should I be smart if I'm not gave the credit. Anyways, my oldest sister Cassie was yelling at someone but I don't know who.

I was getting up to go out to the living room to check on Cassie and see what was going on when my eyes started to hurt. It lasted for about 5 minutes. When I finally was able to open my eyes and see I walked to the door. My door has a mirror on it, ok. When I looked in the mirror I noticed two things.

The 1st. I grew another 5 in. during thing. I know you are supposed to have growth spurts but really, growing 5 in. every night? The thing is all my cloths fit even though I'm about a foot 1/2 taller than I was 3 days ago.

The other thing is my eyes were sea green. I blinked thinking I was hallucinating. I wasn't. I started to freak out but calmed down. I would go ask my mom. I went out to talk to my mom. My mom, like the rest of my family, has brown hair and dark brown eyes. They are kind of short. I ask my mom and she told me that nothing has changed. I went back to my room. I saw my brush so I'm like, "Ok brush your hair you haven't done that yet" my mind is weird. I started to brush my hair. I took one stroke and where the brush touched it was raven black. I was kind of scared my mom would freak but you know I might as well brush the rest of it. When I was done I nervously walked to the living room. My parents and siblings didn't see. I went back to my room, Ya I spend a lot of time in there. I walked in and fell on my bed. There was a tap on my window. I went to look and there was a boy that looked about 15. He had black hair and eyes. He was very pale and had a skull ring on his hand. I opened the window (don't worry there was a screen) and asked him who he is.

"I am Nico Di Angelo."

"What do you want?" I asked

"I wanted to ask you a few questions. Do you know about Greek mythology?"

Yes I know like everything about it."

"Do you like to read?" He asked

"Ya I guess."

Have you read the Percy Jackson and Heroes of Olympus Books?"

"Ya they are like my favorite books" I answered wondering why he wanted to know all that.

"Because those books are real."

"Ya they're real."

"No h said they actually happened." He said

"So the gods are real."

"Yes and you are a demigod." He said. Awesome

"Cool." I said.

"The thing is I already know your godly parent. Your godly parent is Poseidon."

"Really?" I asked. That's even more awesome.

"Yes. But there's more. This is basically like a foster home. Your mom is Sally Jackson. Percy is your twin brother. When you were about 6, Gabe hit you so hard you almost died. You would've but Poseidon took you to his castle leaving a dummy behind. Poseidon took you hear to Oregon to keep you safe. These mortals think you are there kid."

"So, my whole family thinks I'm dead?"

"Everyone except Percy. A while ago he asked me to find your spirit so he could talk to you but we found out your alive. Percy is in trouble. He is in Tartarus and you have to help him. Will you come?" Nico asked

"Yes." I said