So... I've been searching for this fic for a while now, but haven't found hide nor hair of it. It's especially frustrating because I remember certain details, but not enough to find it through google.
It's set in a A/B/O-verse, in a slightly spin-off AU-verse, because I remember mentions that the Winchesters
still went hunting (but Jessica is still alive... I think).
The actual fic depicts a certain course that Sam in taking at university (not sure if it's Stanford), about the breaking of stereotypes of Alphas and Omegas. To do this, the teacher has them write down the three most important things their main caretaker taught them (in Sam's case, Dean) and with those 3 as clue, the class has to figure out what the person mentioned is. (after handing them back to the teacher, so no one knows whose list it is)
Sam writes down two obvious (and one not so) alpha characteristics, and his class agrees on the verdict 'Alpha', but, to the surprise of everyone, Dean is Omega.
(I think one of them was 'learned how to clean a gun', but I'm not sure)
(I also remember the teacher of the course being especially pleased when it was Sam's list's turn, because it clearly broke the mold and (finally) got Sam really thinking about his brother)
Throughout the fic, Sam is kind of a prejudiced assholy little brother, though it's more because he's clueless than deliberate choice.
I don't remember any pairing, simply because they weren't the main focus. I know there wasn't any wincest, and Sam might have been seeing a female character, but I seriously don't remember.
I hope I remembered enough details to spark someone's memory and that you can help me find it ^^' (I knew I should have bookmarked it)
(first time requester here; I hope I didn't do anything wrong...)
Found! Link in comments.