I am starting to think I imaged this whole story!
I am pretty sure it was by bitchandjerk .  

It is wincest or pre-wincest. Dean was placed in an institution or he placed himself there after Sam went to Stanford. Sam comes and gets him out and moves them into and apartment. Dean is on a ton of medication and they decide to ween him off. Jessica was their next door neighbor. Dean has flashes of what the future would have been like but it is all very cryptic.

Am I going crazy or is this really a story by him?