Ruby's assessment of Dean's condition was met with a non-committal grunt as Cas fumbled for a lighter, thumbing awkwardly until it sparked into life and re-igniting the spliff. That he was... uncomfortable with what Dean and Ruby had been doing would be an understatement – he understood the necessity, sure, or at least told himself that he did, and he understood that 'wrong' didn't really mean anything now when they were all damned anyway. But he could still remember when Heaven had had the gall to expect Dean to pick up the knife again, could recall how it had torn at his charge, how he'd begged (or as close to begged as Dean Winchester could ever allow himself to go) them not to ask that of him. That fire – infuriating, yes, but brilliant – was just another casualty of the war, one Castiel mourned as he would the passing of any dear friend.
Something of Ruby had died as well. She played the part better than Dean, granted, tried to carry on just like old times (and he was grateful for that, because it helped keep the rest of the world outside) but it was plain to see, and it didn't take a genius to know what that part was.
He frowned slightly, taking a toke, stretching for something 'good' to tell her, something to keep the shadows at bay. Something real, for all she'd given him permission to lie; those flimsy fabrications were for his devotees, not people he actually gave a damn about. The garrison hadn't ever taught him those wards – the ones for those persistent demons who plagued humans; sorrow, fear, pain - so he'd had to learn to improvise.”You have nice...” - he paused, fishing for something appropriate and genuine - “... elbows” - then grinned, and took another drag, slipping an arm around her with lazy familiarity (one more thing his experiments in mind-expansion had helped with).
“The world doesn't get in here” Cas explained, his languid gestures leaving spiralling smoke trails before he handed her the joint back. "We are what we always were, and..." - another pause, as something in the corner caught his attention, head tilted to observe - "... and even in the darkness there's colours."