Disclaimer: I don't own SPN.
No light, no light
In your bright blue eyes
I never knew daylight could be so violent
A revelation in the light of day
(No Light, No Light, Florence and the Machine)
No Light, No Light
Dean looks deep into the blue orbs, but it's no use.
They hold no light.
The suit and trench coat have been replaced by baggy white clothes; clothes Sam had worn just before Cas sapped the crazy right out of him; clothes his little brother would have continued to wear until the end as Dean sat at his side, confused, helpless, and very much alone.
Only there was no end. Not for Sam.
And he's grateful. Maybe too grateful. So glad to have Sam back—Sam, who he could not imagine life without. Happy and whole again, even if just for a moment, unaware of his taking such a large sacrifice for granted. But he does, and he knows it now. Hell'd strapped itself to Sam on his way back from the Pit—it hadn't left, not really.
Lucifer had simply swapped bunkmates.
He hates himself the minute he passes through the doors, the familiar sound of Sam's footsteps not far behind. He hates himself for not doing a damn thing.
Dean had looked deep into the blue orbs, but there'd been no point.
All the light he remembered had vanished long ago.
And they are no longer Castiel's eyes.