Hello, this will be my first fanfiction. I will try to write everything week. Hopefully, I will finish this before my spring semester start.

Anyway, I know I do not like incest, but Kamui is not blood-related to both side of the family, Hoshido/Nohr. I really ship Kamui/Corrin x Leon/Leo. X) Thus, the story will be about them. (Still….even if their your step siblings and not blood-related …. Is ew, but they are cute together)

Title: Falling for Kamui

Time: AU

Pairing: Kamui X Leon (A little TakumixKamui, a love triangle and also KamuixCyrus)

Rated: K

Warning: I am sorry, but I am really bad with grammar. Please do not be rude about my grammar I know how terrible my English is. Is just ….hardly anyone is writing KamuixLeon (;-;)/! I will have someone check it.

Disclaimer: I do not own the game.

Summary: Kamui is raised by a rich family in a land called Nohr. She does not recall any memory of her childhood. Everyone believes that Kamui is related to the rich family in Nohr beside the ruler of Nohr and the two eldest siblings. She got along with her four siblings. However, only one try to keep his distant from Kamui. He end up having deep feelings for his older sister but know it is wrong to fall in love with his older sister Kamui. Will Leon manage his feelings? Will Kamui accept his feelings or still treat him as a little brother? Read to find out.

Chapter 1- Sin

"Leon!" A shout coming from across the hall of the Nohr palace. "Oi! Leon come play with me!" the little ten-year-old girl kept shouting; dashing towards the dining room.

A little blond hair boy, wearing light blue button shirt, tuck in with black shorts, and holding a book while sitting on the sofa at the dining room. He jumped a little by hearing his older sister shouting again. 'Tsh…Not again' he closed his book and begin to hide under the sofa.

"Leon?" The little girl pop her little head in the dining room, looking for her little brother. She look around and sigh. "I wonder where he went" she pouted. She then runs up the stairs.

"Master Kamui! You need to put your shoes on!" Kamui's butler shouted and tried to catch up with Kamui. "Master Kamui do not run up the stairs with your bare feet"

Leon waited until everything is silent. Before coming out of the sofa, he had to check around if there is no one around. 'Close is clear', he came out of the sofa. "Ho-ho….hiding from your older sister again, huh my cute little brother" Leon jumped a little again. He turn his head and see his older sister Camilla, who is behind the sofa wearing a black blouse with tight white pants. She grinned. Leon blushed a little and hide his face with his book.

"Don't hide from your older sister Leon, it is rude" She patted his head.

"Why don't you play with her instead of me," Leon said with coldness to his words. 'You favored her more than I do' he thought.

"Leon, I wish I could but you know me and Xander are always busy by helping father" she continue patting his head.

"I know…is just " Leon stop his sister from patting his head and started holding Camilla's hand, " I do not want to be close to her" Leon blushed.

"Oh…." Camilla grinned, knowing his little brother feelings toward Kamui. "I'll support you" She kissed Leon's head and walk up the stairs. Leon stares at his sister walking up the stair with a surprise looked. "What does she mean, she'll support me?" he said and went back to his book.

Leon is afraid to be near his older sister Kamui. Every time, he played with his older sister, he always have this strange feeling. When she smiled towards Leon, when she holds Leon's hand, when she hugged Leon too tight, though Leon always pushes her from hugging him, and when she goes to his room just to sleep together with Leon, he always feels his heart ache for some odd reason. He is probably too little to understand these emotions.

This one time, when Leon first hide from Kamui from playing with her, he spotted Kamui talking to a little boy, who looked about the same age as Kamui. He looked like he was training with his father for becoming a knight. The little boy seems to ask something from his father and his father nodded. Then the little boy grabbed his sister Kamui's hand. He saw his own sister blushed from his warm smiled. Leon felt his heart ache deeper. His chest hurt so much from seeing that sight. He remembered that it was his older sister Camilla that took Leon away from that scene.

That is when he stop playing with Kamui. He had to stay away from her. He will feel hurt if he does. Leon stops reading his book. "I FOUND YOU!" Kamui jumps and hugs Leon tight from behind. Leon's face turns red like a tomato.

"MASTER KAMUI! Don't bother your little brother with his studies" The teenage butler grab Kamui's arm.

"No!" She holds Leon tightly, trying not to let go of him. Leon felt irritated now. He wonders how he is related to his older sister.

"It's okay, Jacob," Leon said, "She is not bothering, I need a break now" Leon turn his head and gaze at his sister's eyes with a small smile. Kamui feels joy and hugs him even more tightly. "Yay! You are the best adorable little brother" Leon could not breathe.

"Master Kamui you are choking Master Leon!" the teenage butler Jacob gasp and pull Kamui off of Leon so he can breathe. "If you insisted then I will take my leave Master Leon" He already pull off Kamui from Leon and then take his leave.

"Okay now that he is gone! Let's go!" Kamui grabs Leon's hand from the sofa and forces him to go outside. Leon blushed a little. For some odd reason, he does not want to let go of this hand. 'Damn…I give up" he whispers.

"Huh, did you say something" She turn to see Leon but he hide his tomato face with his bang, "Nothing…" He said.

Leon cannot help himself. No matter how many times he hide from his sister, she will always bug him to play with her. Even when he told Jacob not to let her find him. Sometimes it is a headache for Leon. But, he does love seeing his sister smiled so brightly towards him. In a way, it does ache his heart but is not painful, is more like it is warming his heart. He loves this feeling. Still, he feels like these feelings is a sin. He must stay away from her as possible because they are siblings.

Well, there goes the first chapter. Yeah, the first chapter take place when they are young. Idk their age gap in the game so here is what I think is the age gap.

Elise is 4 years younger than Leon

Leon is one year younger than Kamui

Camilla is about 4 years older than Kamui and about the same age as Jacob

Xander is 2 years older than Camilla

So in this chapter

Kamui is 10

Jacob is 14

Leon is 9

Elise is 5

Camilla is 14

And Xander is 16

Cyrus is 10

So yeah o.e also…I will not describe Kamui appearance (just clothes) because Kamui is an avatar and you are the avatar so is whatever you want to imagine Kamui appearance.

I hope you like it.