Elastic Heart by Sincestiel

Elastic Heart  - Sincestiel

Sam initially fails to tell Dean they are related upon falling in love with his half brother. A well written, highly introspective fanfic.

“Tonight we can have it all, remember? So, just for a little while, let me love you. And then, tomorrow, we can be whatever you need for us to be.”

Source: http://archiveofourown.org/works/8377516?view_full_work=true