This fic is super old and very long. I dont remember there being chapters, but it was several parts of a series. I can't remember any titles, but I know that it followed the actual story of Supernatural seasons throughout the years, but with Sam and Deans relationship and how they got together. 

I remember in the teenage years right before sam left for stanford a character named Dom who worked with Dean at a garage, really liked sam and would flirt and try to take him out on a date, and Dean was really jealous. Dom and sam almost have sex but sam cant go through with it bc he's in love with dean. Dom helps sam leave for stanford. Dean punches dom in the face and breaks his nose.

in the WAY later years after theyre together sam and dean have dinner with Dom and his new boyfriend, and sam and dean are married at this point i believe. Dom still tries to hit on sam, and dean gets jealous again.

Anybody? :)