Author's Note: While there's something to be said for wordless communication and reading between the lines, this latest episode really left it all a bit too vague, so I started filling in some discussion and Dean's Issues got the bit between their teeth and started running.

Dean was refusing to be drawn out to talk about what he was going through. Again. Sam had to resort to being purposefully obtuse, and even then it wasn't until they'd gotten all the way back to the bunker and parked in the underground garage that Dean finally muttered, "It's not about dying. It's about not dying."

Sam turned that over. "Living?"

"Think about it. Cain could only be killed by the Blade, and the Blade can only be wielded by someone with the Mark. If he could've killed himself, I think he'd have done it; I tried getting myself killed, and that obviously didn't take. There could be others out there with the Mark, but I doubt it: say what you want about the guy, but he believed in cleaning up his messes. So where does that leave me, Sammy?"

Sam sucked in a breath. He remembered Lucifer gently scoffing away his own defiant declaration that he'd die before saying yes, telling him he'd only be brought back to life. "You're worried you can't be killed?"

"It's the first time since I was four years old I'm not thinking I could die, at any time. How many thousands of years was Cain wandering the earth? I'm staring down eternity and it's scaring me . . . well, obviously not to death." Dean waited for Sam to huff at his pun before continuing. "But how the hell am I supposed to keep going that long? Everyone breaks, sooner or later. I've broken. I'll break again, and there'll come sometime you won't be there to pick up the pieces."

"Dean, I've told you before I'm not leaving you alone in this. I don't care if that means I have to go find a goddamn fountain of youth, I'll stick with you as long as you need me."

Dean pointed at him. "See, and that? That just scares me more, because how far are you gonna let me drag you along with me?"

Sam furrowed his brow and shook his head, "What? You think I've got better things to do?"

"Sam. Sam, what do monsters want when they're not killing people horribly and eating them?"

Sam hesitated. "Um, to live a normal life, settle down somewhere?"

Dean's bark of laughter was painful. "How are you still so dewey-eyed? I meant, monsters want to make more monsters."

"I guess that's the difference between you and me. So you're saying, you want to give the Mark to more people?" Sam thought about it, and his next statement held certainty. "You want to give the Mark to me."

Dean couldn't look at him. "Part of me, yeah. Is that fucked up or what? Wanting to make sure if I have to keep living, nobody can ever kill you. Nobody but me. Cain said it was inevitable I was gonna kill you eventually, but I can damn well say it ain't gonna happen anytime soon. How many centuries you think we could make it, if we were the only two capable of killing each other?"

"Probably a lot," Sam said dryly. "I'd do it, you know. I mean, it's a stupid, terrible idea, and I wanna spend a lot more time exhausting all our other options first, but if it came down to dying and leaving you alone, or taking the Mark? I'd do it."

"You only just got rid of your residual demon blood and you want me to think it's okay to jump some other kind of evil into you? This is not a freaking friendship bracelet, Sam."

"Maybe I'm used to running around with a bit of evil, Dean. You wanna know something I never told you? Remember that time I was soulless and thought temporarily vamping you was a solid hunting strategy?"

"Hard to forget that time," Dean snorted, but Sam plowed on.

"That wasn't just me being a dick, Dean, I had genuinely miscalculated how mad you'd be about it. I didn't have the empathy to realize you'd take it personally because if you had done the same thing to me, I wouldn't have gotten upset."

"Sure, of course you wouldn't, because you were soulless and didn't care about anything."

"No, I mean, even when I had a soul. I wouldn't have minded that much, knowing you had the cure and were gonna be there to fix it."

"I don't believe you. You were sure mad as hell about Gadreel."

"That was different because it wasn't so we could take down a monster or save the world. That was you screwing everything else to save me, and keeping the lie going because you suspected I wouldn't make the same call."

"Fine, whatever." Dean leaned back against the seat, trying not to feel a bit of warmth inside that even soulless, Sam hadn't really been trying to get rid of him. Trying to be more horrified at the lengths Sam would apparently not balk at to stick with him. The Mark gave a warm little tingle on his arm, wanting to reach out and clasp Sam's arm right there and then. He ignored it. The future stretched out ahead of him, long but not quite so bleak as it had seemed an hour ago.

He let himself believe, for a little bit, that he wasn't going to have to face it alone.