The night that Sam leaves Dean gets laid. Then he gets the shit kicked out of him by the girl's boyfriend. He stumbles into the living room of the crappy little house they were renting and bleeds on the floor in front of his father like a dare. John just stands still, stares past his son as Dean shuffles by him and cleans himself up before passing out on Sam's bed.
The next morning, John sits beside Dean, on the bed Sam left behind and watches his him. Dean's breath is hissy, his ribs are cracked and it's all he can do to fake sleeping with any kind of conviction. The bed shifts and he practically holds his breath waiting for his father's retreating steps. Instead, he feels his hair smoothed away from his face and soft stubbly kiss on his forehead. He won't cry even when he hears the door close behind John.
The next week, Dean's still not speaking more than 'yes sirs' and 'no sirs'. John takes off on a research trip promising to be back in a week and promising no end to the grief he'll give Dean if his oldest hasn't smartened the fuck up by then. Dean just sits on the edge of the bed until he hears the sound of John's truck grow dim with distance. He packs his bag, checks out and leaves a note for his father, bullshit about a poltergeist somewhere not far from here. He's in Stanford in 28 hours flat, ready to drag the little bitch home, but when he sees him, books in hand and a smile, a fucking smile on Sam's face, he turns around and gets back to the motel on the other side of the country before his dad figures out he so much as left the room.
The next month, John and Dean have hit their stride again. Salting, burning, drinking and salting, burning and drinking. So it comes as a surprise to Dean, the kind that sucks the wind from a guy, when John hands him an address and shot gun and tells him to go handle this one on his own. It turns out to be nothing, well nothing supernatural and when Dean gets back, John is at the table, bottle in front of him, staring into space. Then Dean gets it, 'So, how is he?' He asks his father and pulls out two glasses.
The next year, Dean spends most of his time alone. He goes days without hearing the sound of his own voice. And ironically, after years of pleading and praying not to be left behind, he's settled into it. He hunts, he researches, he fucks, he drinks. He avoids Palo Alto, all of California really, like it's a hot zone. Until one day, he's down the street from a shabby little apartment house in the student ghetto watching the big geek, who's obviously still training judging by the way he's filled out, move a couch and bookshelf and bags and rugs and a huge bed inside from a moving truck, all under the careful instruction of some fucking knock out blonde who can't take her eyes off the shaggy haired bitch. He waits until they go out, arm in arm, and breaks in, muttering to himself about the state of the useless locks. He finds Sammy's bag and stuffs the box into it – salt, the knife with the curved blade, the bottle of Jack, the first aid kit, the rosary and the holy water. And the last picture he had of the two of them. Then he pulls the picture out and scribbles a note on the back and stuffs the whole thing back just like it was.
The next year he gets shit faced and doesn't leave his motel room for three days.
The next year he's staring at Sam in the passenger seat trying to ignore the smell of smoke, choking on his regret and selfishness and weakness and greed. He tries to think of the words that will somehow make this better. He tries to think of an apology that won't sound stupid and hollow. He tries not to stare. Sam's face gets harder, angrier, more hateful and Dean's waiting ready for the blame, practically jonesing for it. He doesn't expect the determination, the sound of Dad's voice coming out of Sam's mouth. And suddenly he doesn't know what's worse.