[found!]specific wincest, valentine's day, season 7 maybe
Hi, I've been looking for this fic for a really long time. I remember Dean always said be my valentine to Sam on valentine's day, and one time jokingly gave Sam a small plastic heart as a valentine's day gift which Sam kept secretly. They'd been having sex, but Sam felt bad because he thought Dean didn't really love him. At last Dean found the plastic heart and fix everything. I don't remember much of it and sorry for my bad English.