LET HIM GO
Castiel stood at the end of Dean Winchester's hospital bed; Dean who was always young and strong, at least always in Cas' mind. Dean who's hair was now grey and his body battered by age, shallow and laboured breathing was the only sound audiable as Sam slumped back in the chair to the right of Dean's bed, hands over his face, Cas looked down at Dean: Dean Winchester who saved the world more times than anybody would ever realise, who had died so many times but always found his way back for family and for love.
Castiel knew that this was it now. The final death of Dean WInchester, there would be no saving him this time, no fighting off hell hounds and demons. Just the loss and the heartbreak. A sharp breath forced Sam to look up at the Angel, Cas could only muster a tilt of the head at Sam's questioning, tear stained face
"hey Dean" Sam began. Pausing for an answer he knew would never come "I'm proud of us" he whispered, Cas stood motionless, a single tear running down his face.
A hand placed upon Cas' shoulder startled him and forced him to turn around, expecting to see Dean's Reaper, but there was no Reaper, only Death himself
"It is time Castiel" he whispered curtly "it is time to let him go" with more finality in his tone "I am sorry for your loss, I know the... Bond you both shared".
Outside in the hospital parking lot Sam and Cas were stood leaning against the Impala in total silence until
"I need to get out of her" Sam announced
"As do I" Cas replied, he looked at the Impala secretly hoping that Sam would let him ride shotgun as his brother did so many times before, Sam glanced over at Cas looking at the passenger seat before taking the keys out of his pocket
"Hey Cas" chucking the keys to Cas "I'm too tired, you take the wheel" to which Cas just nodded, got in and started the engine just as Dean had taught him to years ago.
So together Sam Winchester and Castiel with no real direction and both with broken hearts simply drive away.