Premise: Sam does not save Dean. But Ruby throws him a bone. She's discovered that Dean has a son. Sam then sets out to track down as many of Dean's one night stands or extended flings that he can remember enough about to maybe find again. The search takes him to Dillon.
There won't be much in the way of the supernatural in this. It would be about Sam choosing to stay to Dillon because he wants to be near the one blood relative he has left in the world, trying to fit back into the mundane world (possibly getting a job at Dillon High and coaching some Soccer), dealing with seeing a girl who looks just like Jess, and wrapping his brain around the incredibly fucked up (but ultimately very loving) family he's stumbled into. (No, it's not going to the Tim/Sam place. Although Sam's certainly not going to be celibate.{weg})
I don't know that I'll ever get more written, but this bit stands alone as vignette.
That said, if you're still with me
( here's a taste )