2x01
John can't save Sam
John can't save Sam. He can't. Maybe if he knew before what he knows now, how the world would hang in the balance of his youngest's word, maybe he could save his relationship with his son in order to save everything. Maybe the end of the world would be enough for him to be a real parent. To let things slide, to let them go, to not go to the mat for every single argument. To make him act like the grown up at least once.
Maybe if Sam trusted him, believed in him, loved him... But John screwed that up a long time ago. So many years ago he's not even sure when it exactly happened. Sam has no trust in him, nothing but resentment and contempt and hurt. John can't save Sam.
Dean can.
John knows it. The only one who can save his youngest is his eldest. Even after everything, Dean is still the only one Sam trusts, the only one Sam listens, the only one stubborn and self-righteous Sam allows himself to follow. Dean is the only one who can save his brother and he won't even care if the world is saved doing so.
Dean can save Sam.
He can.
Dean is dying. Brain injury, not breathing on his own. Sam thinks his spirit is walking around somewhere. Probably running from reapers.
Dean will be dead by sunrise and John will lose both his sons. Dean will die and no one will save Sam. John will have to either lose his baby boy, Mary's baby, to the dark or kill him (he won't, he won't, he will never).
John can't kill Sam. Won't. Ever.
John can't save Sam.
Dean can save him.
Dean is dying.
Dean has to live.
John makes it so. Saves Dean to save Sam and at this point he really, really doesn't care if the world is saved doing so. He just wants his boys safe. Together.
He tells it clear to Dean: save Sam or kill him. Because he knows. He knows. Dean will never kill his little brother, his Sammy, this kid he loves so much more than the world or himself. So Dean will save Sam. He will.
Dean is alive. Sam is beside him. Sam is smiling.
Smiling.
John can't remember the last time he saw his son smile with true happiness. Years, definitely. Maybe a decade.
He takes Sammy's smile with him as he walks back to his room.
The fight is not over. But John has nothing to offer but a useless old gun.
And his soul.