Sam could drown in the cornfields, he thinks sometimes. Just walk in and never come out and no one would ever notice. Some days Dean's the only tether keeping him from drifting away out into the endless sea of green.
With Dad away, Sam runs wild with the boys in town, spends all day browning under the Kansas sun and comes back with a second skin of dirt and sweat and feral youth. He learns to swim in the town's one pool, half-abandoned and bright green with algae; after, Dean makes him scrub down the shower stall once he's done rinsing off. The other boys teach him words Dean doesn't know, dare him to kiss their sisters, holler like a flock of starlings when he actually does.
When Dad's home, Sam skulks carefully through the bunker, tries not to draw his attention because it upsets Dean when they throw words at each other. Instead he hangs out in the warm bright haven of the kitchen, or the solitary dim safety of his room, or sits in the Impala with the radio playing as Dean carefully details his beloved car for the third time that week. He watches the kids on TV grow up and leave to find some wider world and wonders if (when) he'll do the same.
If Sam ever tried to picture his father's heart, it would be a card catalog or a locked file cabinet. Or no--there's a cursed knife carefully labeled and packed away in the very back shelves of storage room 38, which always cuts you no matter how it's held. (Dean's always there, ready with the bandages, but Sam would rather just let it bleed.)
There are demons everywhere, his father tells him when he's fourteen and beginning to beat his wings against the bars of his buried concrete cage. There are demons here, Sam thinks when some meaningless detail overlooked means yet another angry lecture, when Dean spends a week saying nothing but yes sir, when the liquor bottles gather and empty and are replaced.
There aren't any demons in town, just a friendly librarian who gives him books about going to faraway places, about boys (and girls) who say no and go their own way, even if it costs them all they had--because all they had wasn't very much.
And Sam runs wilder and kisses more girls (and more than kisses) and fights with their brothers and stares out across those fields to some better life on the other side--and all ropes eventually must succumb to a knife.