As Dean ran through his plan, Sam felt a sinking feeling growing through him. Dean was calmly explaining everything to his brother, as if he wasn't talking about trapping himself with an angry archangel for eternity.

"That's your plan?" Sam said, disbelief arching his eyebrows. "You want to be… buried alive?"

"Buried's not safe enough," Dean said. "The plan is to pay a little hush money, charter a boat to take me out to the Pacific. Splash."

Sam didn't know how to process what his brother was telling him. "You and Michael, trapped. Together. For eternity."

"Yeah," Dean replied. He held Sam's eye contact and raised his chin. Sam could feel Dean defying him to argue.

"You do realize how insane this is, right?" Sam said, the panic he was beginning to feel making him clip the ends off each syllable as he spoke.

"It's the only sane play I've got," Dean said. Sam scowled and Dean continued. "Michael gets out, that's it for this world. And he will get out."

"But how do you know that for sure?"

"Because I do. Because I can feel him in my head. That door is giving – I can feel it giving!"

"There has to be another way," Sam began.

"There's not, okay?" Dean said, cutting off Sam's argument. He blinked a few times and continued. "Sam, you've tried. Cas has tried. Jack. And I love you for trying."

Sam felt frozen in place. Dean's use of "I love you" was setting off alarm bells in his head. Dean was serious about this. Dean was preparing to say goodbye forever.

"But none of it's gonna work," Dean said.

"We don't know that!"

"Yeah, we do," Dean said, certain.

"What?"

"Billie."

"Billie?"

"She paid me a little visit," Dean explained. "She said that there's only one way that this ends right." He placed a fist on the box between him and Sam. A metallic clang accompanied his movement. "And this is it." Sam was shaking his head now. Dean's words were making him feel sick. "This. Right here. This box." Sam dropped the eye contact he had been holding with his brother. His gaze fluttered around the ground as he tried to calm himself. The panic gripping his heart was making it hard to think. But Dean was still talking, his fingers tracing the sigils on the top of the box. "So she gave up the special recipe and all I had to do was the work." Dean's voice was less steady now. "It's fate."

Sam's eyes were wide as he tried to keep away the tears that were threatening to form in them. "Since when do we believe in fate?" He looked at Dean again, clenching his jaw.

"Now, Sam," Dean replied. "Since now."

Sam took a few deep breaths. He was done responding to Dean's explanation for now. He was ready to ask the question that had been burning in his mind. The one thing that was hurting the most. Screw Dean's plan. Sam huffed out an angry breath. "So," he said, "you came out here to see Donna? To see Mom? On some… some what? Some sick, secret farewell tour?" The tears were stinging Sam's eyes now. "You were gonna leave. And you weren't even gonna tell me?" Sam's voice broke on the last word and it came out barely above a whisper. Another angry huff of air. Sam needed to make sure he was getting through to Dean. "Me," he repeated.

Dean's gaze was shifting around. But Sam wasn't even close to done. "Do you realize how messed up that is? How unfair that is?"

Sam flinched as Dean's voice broke through his at a yell, "I didn't have a choice!"

Sam scowled and shook his head. Bull. Dean wasn't going to get away with leaving him that easily.

Dean's voice was shaking but he kept going. "You were the last person I could tell, the last person I could be around because you were the only one that could've talked me out of it!"

Sam blinked.

"And I won't be talked out of it. I won't. I'm doing this." It was Dean's turn to break eye contact. "Now you can either let me do it alone. Or you could help me."

Sam closed his eyes, a pained noise escaping his throat.

"But I'm doing this," Dean repeated.

Sam was shaking his head again. This was too much. His jaw worked as he tried to hold back a sob. He glanced quickly at Dean and then turned around, hiding his face from his brother. Dean was quiet. He obviously knew Sam needed time to gather himself.

Sam turned around, biting his bottom lip when it shook. "Alright," he said.