Her womb

Bran tried pulling out, he truly did. Arya, however, was too tight, and he was too slow. As he began to slide out, a burning sensation washed over him. His cock squirted wildly, dumping his seed in his sister's womb. He then managed to pull himself out, his manhood still spasming and decorating Arya's cheeks with spurts of his cum.

The girl fell limply on her side. Bran couldn't see her face very well in the dark, but he'd imagined that her expression would be of shock, same as his.

"I-I didn't mean to..." He tried to apologise.

"U-umm... it's a-alright really, I'll just wash it out." She responded hopefully, although Bran didn't know if she was telling him or herself.

"Do you need any help?" The Stark offered.

"No, no thanks. I s-said it's alright." Arya slowly pulled her skirt down. Being honourable, the boy helped her get on her feet and opened his chamber's door for her. He was rewarded with a peck on his cheek, making them blush a little. He was a bit astonished with it, barely noticing that she was already gone.

He went back to his bed, his sheets a bit wet from her juices. He sighs, his cock soft. The insides of a woman felt amazing, he didn't care that the woman happened to be his family. He still felt her kiss on his cheek. He rubbed it, thinking about her image. He smiled, what he'd predicted earlier was already happening. Whenever he was thinking about his sister, the image of her naked bottom did come to his mind.