The radiator clunked and the lamp lights flickered for a second before stabilizing, the storm raging on outside.

"What do you mean, 'from there it's up to us'?" Dean asked the angel, voice heavy.

"I mean I can get us in and protected by the power of your consent, Dean, but I can't get us out without the power of Sam's consent," Cas explained. He took a step closer. "Dean, you need to reach Sam. In the cage," Cas clarified, like it was an insurmountable feat, "and get his consent for us to help him."

Dean shook his head.

"If I'm in the cage and he's in the cage, won't I be able to reach him?" Dean asked, confused.

Cas licked his lips nervously and looked away.

"Hey!" Dean called and Cas turned back with doubtful eyes. "What? What is it?"

"You'll have to convince him that it's you."

Dean shook his head, not getting it.

"Dean, you have..." Cas trailed off, trying to find the right words, as Dean stared daggers at him, "a... a bad track record. With your brother."

It took a minute for Castiel's words to sink in. When Dean finally understood, dread and darkness seeped into him, chilling him to the core.

"No," he snarled, threatening. "That," he paused, doing his best to rein himself in, "is not a question, do you understand me?"

Unlike anyone else in the world or any other realms of heaven or hell or purgatory, Castiel raised an eyebrow and sighed as he turned away, shaking his head.

"Hey!" Dean yelled, outraged. "Do you-"

"No," Cas boomed, turning quickly around to face him, "do you understand the stakes here? If you don't convince Sam it is truly you and get his consent, then all of us will remain in the cage. Forever."

Dean backed off.

"Cas-"

"Do you not get that Lucifer has worn your face not only in hell but in Sam's hallucinations on Earth? Do you understand the last time you begged his consent, it was to be possessed by a corrupt angel? Do you understand... the number of times Sam has been burnt by trusting you?" Castiel finished, his voice sharp as nails, eyes blazing as he stared into Dean, forcing him to face these realities.

The words reverberated inside Dean, knifing through his defenses, pulling out the truth and pushing all doubts and insecurities about his relationship with his brother to the forefront, screaming at him that Cas was right. Screaming that he wouldn't be able to reach his brother after all the mind games and tricks Sam had been subjected to just because he had Dean for a brother.

"Dean," Castiel's voice cut in, but Dean was lost in nightmares. "Dean," Cas said more urgently, "stop. I know what you're thinking. You don't even have to pray anymore," he said offhandedly. Dean's eyes lifted to his friend, slightly surprised and hurt by the callous tone.

Cas softened and tilted his head lower so he could look up at Dean with wide, earnest eyes.

"None of it has ever been your fault, Dean," he said, utterly sincere. Dean felt himself shaking and covering his mouth as if to stop his lips from trembling, his tears from falling. "But we're not doing this - we're not risking everything - just for you to fail once you get to Sam."

Dean swallowed and nodded, doing his best to regain composure.

"You just have to convince him. One, that it's you. Two, that he must consent to you and me."

Dean nodded, sniffing and rubbing his face, digging into his eyes. This really was terrifying, he realized. There was absolutely no way Dean could be sure he'd be able to reach and get that from Sam. It was right here - right now - this very conversation, that Dean realized their odds of success were low; astronomically low given the lynch pin was a traumatized, tortured and delusional little brother who was currently refusing to say 'yes' to Lucifer.

Dean looked at Castiel and it dawned on him that Cas had already made peace with how this could be the end of his story. That he might end up spending eternity in this cage with Dean, Sam, and Lucifer, and it still would have been worth it. For Sam.

Now it was Dean's turn to get over it.

"How much ti..." Dean went quiet, "time will we... have?" Dean's voice was breaking but he didn't care. Especially not with Cas, who simply kept the same open and understanding expression he'd had before.

Cas tilted his head, considering, before looking back up at Dean.

"I don't know."