It almost could have been the start of a bad joke. A semi-fallen angel and Lucifer's ex-vessel sat together in a secret hideout. Sadly, it wasn't a joke, and it was the harsh reality of Castiel's world, which very recently had imploded. He was sitting beside Sam in the Men of Letters bunker, both of them staring blankly into empty space, a sorry pair soaking in their own misery and suffering.
Castiel was the first to break the silence. "What were the trials to close Hell?" He asked, and Sam didn't even lift his head as he replied.
"Bathe in the blood a hellhound, rescue an innocent soul from Hell and cure a demon," he said flatly, his thoughts focused on what Dean might be doing, what evil and chaos he might be creating. He remembered Dean mentioning that when Cain had received the Mark he'd murdered thousands – Sam shuddered to think of his older brother following in such footsteps.
Castiel was silent for a moment, considering, thoughtful. Then, "I think I have an idea."
"And what would that be, Cas," Sam asked mockingly, his voice eerily reminiscent of Zachariah's. "Can you give me back my brother? Can you fix the world?"
Cas wasn't thrown by Sam's bitterness in the slightest, his mind connecting dots faster than a human, but far slower than an Angel. "Yes," he said slowly, not rising to Sam's provoking tone. "Yes, I think I can."
Sam's head snapped to face Cas, the angel's words sinking through the haze of fear and sorrow at last. "What?"
"If I complete the trials, I can fix everything," Cas murmured distractedly, thoughts still racing.
Sam snorted. "Yeah, but you still won't give me back Dean. He'd just be stuck in Hell, forever." His grief-filled mind still wasn't quite up to speed, and Cas shook his head in disagreement, finally looking over at Sam with a piercing gaze.
"Not if I cure him."