What if Castiel didn't let Sam out?
Dean opened the tiny window/door to the panic room to check on his brother.
"Dean, let me out," Sam said, when the noticed the window opening. "This isn't funny."
"You've got that right," Dean said. "You're staying in there until you dry out."
"You're turning this into some ridiculous drug intervention?" Sam asked. Dean was such an idiot. "I'm not drinking the demon blood for kicks. I'm doing it to get strong enough to kill Lillith."
"This is as far from strong as you can get. This is weak, pathetic," Dean said and shut the window. He didn't want to talk to Sam anymore. This wasn't his brother. Not now. Hopefully when he dried out, he would be again.
He went up the stairs with Sam's screams of "LET ME OUT!" following him. It was hard listening to him scream like that, but he had to be strong. He hesitated for just a moment and then he continued up the stairs.
"How's he doing?" Bobby asked.
Before Dean could answer, they heard screaming coming from downstairs. "How long is this going to last?" Dean asked.
"Let me check my demon detox manual," Bobby said, reaching for his books. "Oh, that's right nobody ever wrote one."
Dean rolled his eyes. Now was not the time for sarcasm.
"Cas!" he yelled.
"You really think your angel pal is going to be able to help with this?" Bobby asked. They had seemed pretty useless up until this point. Besides, he was still mad that this Castiel guy had knocked him out at their first meeting. He had had a headache for days afterwards.
"Maybe he can insta-detox Sam, or something," Dean said.
"I can't," Castiel said as he appeared immediately beside Dean.
"You scared me," Dean complained.
"You just called me."
"Can Sam do it? Can he kill Lillith?" Dean asked. This was the last thing he wanted for Sam, but they needed to consider all their options.
"Probably, but there are two reasons why he shouldn't."
When Cas didn't say anything else, Bobby prompted, "Well, what are they?"
"First of all, he would need to consume more demon blood. The amount of blood he would need to consume would change him forever. He would most likely become the next thing you would want to hunt."
"Well, that's reason enough for me, but what's the second reason?" Dean asked.
"All the seals have been broken except for the last one. I just found out that Lillith is the last seal."
"What does that mean? Lillith is the last seal?"
"It means that when she dies Lucifer will walk free," Castiel said.
"So, we have to actively try to keep her alive?" Dean asked. That went against everything he believed in.
"No. Ruby's knife won't work on her. You saw that it was pretty useless against Alistair and she's stronger than he was. The Colt has been destroyed. The only thing that can kill Lillith is your brother."
"Great. We tell him that and he won't want to kill her. Problem solved," Dean said.
"You sure about that?" Bobby asked.
"Bobby, Sam wants to stop the Apocalypse, not start it," Dean protested. His brother may have made a big mistake drinking demon blood, but it was for a good cause.
"That may be how it started out, but he's addicted. No telling what an addict will do. Not even one who started out with as good a heart as Sam's."
Sam was pulling on the door, trying to get it opened, but he knew there was no point. Bobby wouldn't build a panic room he could get out of.
"Hey, Sammy," he heard behind him.
Sam spun around. "Gordon?" You're dead."
"Looks like I was right about you all along, Sammy. You're evil," Gordon said, with a grin, as he pulled out a knife. "Dean locked you in here so that I could kill you."
"No, that's not true," Sam said, knowing that it probably was. Dean had said some pretty mean things to him earlier. Dean didn't understand. How could he, when he was so weak and pathetic? That's why Dean had called him weak and pathetic. Because he was. Dean was just jealous of all the stuff Sam could do, how strong he was.
Gordon advanced on him with the knife. He plunged it into Sam's gut, and Sam screamed.
Upstairs, the two hunters and the angels listened to the screams with sadness.
Ruby turned around to see Zachariah. "What's going on?" she asked.
"I've sent Castiel to let Sam Winchester out of the room. Now we just need to wait for him to contact you." They had been working together for a while. Zachariah remembered Lucifer from before he was thrown down to the pit. He had been his favorite brother. Everyone else thought Michael was the best big brother ever, but Zachariah knew better. He wanted to let Lucifer out of the cage and then he would be Lucifer's favorite little brother. Together they would rule the world. Unfortunately, he needed this demon to accomplish the task. Hopefully, Lucifer would let him have some fun with her after this was all over. He heard about torture, but had never actually gotten to do it to anyone.
"Why didn't you let him out yourself?" Ruby asked. Seemed like it would have been a smarter idea than to entrust this important task to someone else. Someone who wasn't even in on the plan.
"Other angels like Castiel. When it's found out that he let Sam out to free Lucifer, he'll be hated. I don't want him as a rallying point after Lucifer kills Michael."
Ruby nodded her head. She understood all about jockeying for position. Besides torture, it was one of the number one pastimes in Hell.