One of the best post-AHBL fics, ever.

The World's A Small Child in the Dark by stele3

Read it and laugh and cry and smile and cringe, yes, cringe, because Dean has this list, you see, of things that he wants to do before his year is up; some of them are funny, some are heart-breaking and some are downright crazy. Dean wants to live life to the fullest, no holds barred and Sam is right behind him every step of the way. But despite indulging Dean in his whims and fancies, Sam never let himself forget that at the end of the day, ( or year ), the demon is coming for his brother's soul, and Sam will do anything, anything to save Dean. An ending that will leave you crying and laughing and aching for them. I love how Sam eventually saves Dean. It is stunning, totally unexpected and it takes my breath away to see what Sam would and could do to not let the demon take his brother. Someone really should point out this story to whatstheirname, Sarah and Rachael, because IMO this is one genuiniely brilliant way for Sam to save Dean.

Sam imagines Dean scrawling this list down in a diner somewhere, sitting alone at the table while Sam was outside or in the bathroom or something, just a quick pit stop between a dozen or so exorcisms and crappy food and the physical ache of car seats. He suddenly feels sick, goes into a bathroom stall and leans over the stained toilet there, his mouth hanging open and his eyes watering. Instead of puking, though, he starts choking up, suppressed sobs jerking his diaphragm but never quite making it past his chest.
He's going to fix this. He has to. He sets aside the urge to flush the List down the toilet and instead puts it carefully back inside Dean's duffel, yanks the shirt back on in a flurry of torn hems, and goes back to the car.