The pounding had stopped when Sam got to the room; instead of battering his way out, Dean was on his knees, attempting to pry the ventilation screen off of the bottom of the door.

As Sam approached, Dean stood up and away from the door.

"You're making a mistake, Sam."

"So you keep saying," Sam answered. He leaned back against the wall next to the door and closed his eyes for a moment. "Do you need anything?"

"I need you to let me out and do my job."

"And since that's not going to happen, is there anything else you need?"

"Sure, I'm going to have to pee sooner or later."

"There's a metal wastebasket in there," Sam told him. "Have at it."

"Seriously?" Dean asked, after a moment's pause. "You expect me to pee in wastebasket?"

"All I ever had in the panic room was a metal bucket."

Dean chuckled. It was a dark sound.

"That's what this is about, isn't it? I just realized. This is payback for me putting you in the panic room."

"Yeah, you're right," Sam said. He bent his head down and massaged the back of his neck. "I'm paying you back for all those times you saved my life by putting me into the panic room. That's it exactly." He sighed. " I'm doing this to save you, Dean. I'm doing it for you, not to you. I wish you could see that."

"All I can see is that now I have the power and you can't deal with it."

"What I can't handle is watching you suffer and not being able to help you."

"I'm not suffering. This is the steadiest, the most in control I have ever been. And I think you're jealous of that. I think you want that feeling back like you had when you didn't have a soul. Don't forget, Sammy, you're a killer, too. You keep it back, you keep it controlled, but even you have to admit, there's a killer inside of you that I couldn't touch, not on my best or worst day."

"I know," Sam said. "And you still never gave up on me." He pushed himself off the wall. "I'm not giving up either."

He walked toward the dungeon, opening doors of their storage rooms and examining their contents as he passed them. Finally, he chose the first storage room in the hallway. He propped the door open and started hauling the contents out of the room, stacking the boxes and files and artifacts into the hallway.

"Sam, what are you doing?" Cas asked, coming up the hallway from the dungeon.

"Making a panic room," Sam told him. He stopped his work and dragged a sleeve across the sweat on his forehead. "What happened with Crowley? Can he find Cain?"

"He knows a summoning spell that should work. I've gathered all the necessary materials; it's prepared whenever you'd like to proceed."

"All right." Sam brushed his hands off and studied the half-empty storage room for a moment.

"Do you think a panic room will be necessary?" Cas asked.

"I think if I can't get Cain to take the Mark back that it's my only option. Dean's not a killer and I'm not going to leave him trapped in that rage, not without trying everything I can think of to save him from it. He's never - " Sam broke off suddenly. He swallowed hard before continuing. "No matter how hard I ever fought him, no matter how many angels and demons or even Bobby told him it was pointless, Dean never, never, walked away and left me to suffer, even when it was my own arrogance that was causing it. I'll do whatever I have to; I'll do whatever it takes."

*SPN*

A half hour later, Sam and Cas stood outside the Bunker's garage door, with a large copper bowl just outside the devil's trap painted on the asphalt at their feet.

Sam lit a match, "Here goes," and dropped it into the bowl. The resulting flash and smoke cleared away to reveal a man standing in the middle of the trap. He was tall, lean, with graying hair and beard.

Cain.

"Who the hell are you?" He demanded of Sam.

"You gave my brother the Mark. I want you to take it back."

Cain's eyes widened in surprise.

"You're the brother Dean didn't kill. Well, well, what makes you so special?"

"Answer the question," Sam told him. "Will you take the Mark back from Dean?"

"Why should I? I told him there were consequences of accepting the Mark. He didn't want to hear them."

Sam regarded Cain for a few moments with a sour look on his face.

"Then we're done here," he said and turned to go back into the Bunker. Cas turned to follow him.

"You didn't tell me what makes you so special. Why Dean never killed you."

That made Sam stop. He walked back to Cain.

"You want to know what's special about me? My brother. He saved my life over and over again. He saved my life when he didn't have to, when he shouldn't have, when he shouldn't have been able to save my life. My brother has gone toe to toe with Death, with monsters, angels, demons, and Lucifer himself to save me. That's what special about me."

Sam turned to go in.

"You're just going to leave me here?"

"You won't help my brother, you don't exist. That devil's trap might start to wear off in the heat next summer. C'mon, Cas."

They walked back into the Bunker and to the storage room.

"Cas, you think you could zap a mattress in here? Maybe a desk and a chair? I'll go get Dean."

Sam headed for the bedroom hallway, walking stiff and slow, as though reluctant to be doing this.

"Dean?" He asked when he got to the room.

"What?"

"I want to let you out of there and show you something down the hallway. Will you please just come with me?"

There was a pause and then, "Yes."

"Thank you."

Sam unlocked the door and Dean pulled it open from inside.

"All right, what? What are going to show me?"

"This way."

Sam led the way back to the storage room. Cas had furnished it similar to the bedrooms.

"A panic room?" Dean asked. "In this place, you made a panic room?"

"Crowley's in the dungeon," Sam explained. He sounded weary. "I didn't think bunking up together was a good idea. I wish I we had a room with an attached bathroom, but the bathroom is right next door to this room. I think we could build a doorway to it through the room."

Sam paused, and sighed, and turned to Dean.

"I'm sorry to do this to you, Dean. You've spent your life taking care of me, saving me, and I wish I could find a way to save you that didn't involve this. But - I'm out of other options."

"Seriously?" Dean demanded. "You seriously think that I'm going to willingly lock myself into a panic room?"

"No," Sam said. "I think I am." He pushed his right shirt sleeve up. "Give me the Mark."

To Be Continued

A/N: I'm not happy with this, it's rushed, but I wanted it done & posted before the finale tonight, so if there are any similarities, I can say 'I thought of it first!' I doubt there will be any similarities, but just in case.