Sam and Dean have a problem and they need Garth's help. (Warnings: Set vaguely in Season 8. Prior knowledge of Mr. Fizzle is helpful. Garth is the main POV.)
Sam is strong. Dean is not. (Sam's headspace, and thus spoilers, for Season 4. Deals with one primary aspect of the season. Two words: D-something, B-something.)
Dean has to take care of a baby, so he panics and turns to Ben for help. Turns out, the baby is the easiest one to deal with. (No spoilers besides Ben's existence) Warnings: not entirely realistic.
This is your future. Because, no matter how you look at it, things won't end happy. ALT SUMMARY: Dean is alone and all he's got is a crappy job and a crappier friend. Also, he apparently sours with age. (End of Series fic) Rated T for swears. Vague spoilers in the form of passing references to unspecified events.
The Winchester way is death and sacrifice. Sam's just doing what they always do. (Spoilers for Season 8: Focuses on what Sam thinks about the whole dying aspect of the Trials.)
Dean keeps losing everyone. It's a cold, ugly process. (Spoilers up to the Season 2 finale)
Castiel has been thinking about this for a long time, but he just can't seem to come to a reasonable conclusion. He turns to Sam in hopes of truth and revelation. No spoilers other than Castiel's existence. Warning: This is dumb.
This is just a cursory reflection of Sam's life. It by no means encompasses all the aspects of this fabulous man. No spoilers, any season.
Sam briefly thinks about Jess. (Geez, she's mentioned every season, poor Sammy boy.)