I honestly don't know if I should call this incest, should I? nahh I don't think you could call this incest.
(Non-beta'ed like always)

She was free and unbound, he was trapped inside his duty unable to break free without breaking an oat he hadn't even sworn. One could say, they were total opposites but they knew better. They knew they were the same, different perhaps, different sides of the same coin that much was true, but the same nonetheless.

"Brother!" She would call, standing in the lake holding up her skirts so they wouldn't touch the water. "Look at the fish!" Her eyes would twinkle and she would smile.
"I see," He would look up from his book, never actually seeing any fish from his place on the riverbank. "I see sweet sister."
She believed him and turned her attention back to the fish that swam around her legs, giggling whenever one nipped on her toes. He enjoyed seeing here like this, for he could not tell for how long it would last.

At night, she would crawl into his bed, never minding his protests about 'being proper'. "No one sees us like this," she would reassure him. "Besides, I had a nightmare." He knew she was lying, she never had nightmares. "A lady should not lie." He told her while he wrapped an arm around her thin frame and held her close. "And a gentleman does not deny a lady anything."

She enjoyed parties the most, she would dress in bright colours, bright blue being her favourite, and dance until dawn. "Brother! Brother!" She cried, lifting her skirts so she could run towards him, golden hair dancing behind her as her twinkling laugh filled the room. "Dance with me brother!"
He danced with her, holding her in his arms and breathing in her scent soaking her in as much as he could. Their dances never lasted long, for he had to dance with ladies which where nothing compared to her beauty and she had to flirt with men twice her age.

Sometimes she drank too much whine and he would find her sitting in the garden, looking at the stars.
"I wish we were born differently." She would tell him when he sat down beside her. "I know." Was his reply. Even if he never told her he wished the same.