Leave it to Sam to ruin the moment.
“I hate it.”
He’d been nearly asleep when the words were spoken, lightly so if Dean didn’t respond it would be okay because at least Sam had tried.
Not quite able to open his eyes just yet, he settled for stroking Sam’s forearm and asking a throaty, “What?”
There was a soft sigh and rustle of sheets before Sam answered. Dean hadn't imagined it then. Sam would have preferred to deliver this news while he slept.
Sam pulled out of Dean's grip and reached out to touch his upper arm, fingers gently tracing over the handprint Cas had left seared into his skin. “I hate it.”
There was nothing in the world that could come between them. The forces of both Heaven and Hell had tried, and nothing was going to tear them apart. Dean understood that, he accepted it, it grounded him like nothing else could; but these doubts had been a part of Sam ever since Dean had come back. “It doesn’t mean anything, Sam. It's just a scar.”
“Dean.” Sam's voice came out a cracked whisper, so full of regret that Dean instantly felt panic seize him.
“No. You know what it is? It's just a mark. Just like some injury we'd get from any other thing we go up against all the time.”
The grip on Dean's arm tightened. “No. It really isn't Dean. I hate that some being left its mark on you, even if it's Castiel.”
Dean didn't even have to ask, because he knew how he'd feel if the situation were reversed. Yeah, there was probably some jealousy there. But Dean knew how to fix that much, at least.
He shifted and turned so he was facing his brother. There was just enough light from the parking lot streaming in through the motel curtains that he could make out Sam’s worried expression in the dim room. “Sammy, listen to me.” He reached up and ran his hand through Sam's hair, and Sam leaned his head into the touch. “This scar is just a scar like any other. It doesn't mean anything. I'm yours, and you're mine. The way it's always been.”
Sam made a frustrated sound. “It isn't – okay it's partly that but that's not all of it. It's not just the stupid scar Dean, it's what it represents. I wanted to be the one to get you out."
“Yeah, well, I'm glad you weren't.” Dean could see the hurt flash in Sam's eyes, but he was not sorry he said it.
“Don't say that,” Sam said, voice rough. “All I wanted was to get you out. To trade places with you... whatever it took.” He tossed the covers off and climbed out of bed and began stalking around the room.
He watched Sam for a long moment, debating how far he should take this, and then he took a deep breath. “Sammy, I'm only going to say this once because this conversation is getting a little too girly even for you.” Sam directed a half-hearted bitchface at him but there wasn't much heat in it, so Dean continued. “I'm glad it wasn't you that did something to get me out, because that would mean you were down there instead and I couldn't live with that any more than you could. What matters is I'm out, and I'm here now. With you. Where I'm supposed to be.”
“I know, but I hate this Dean. All of it.” He paced from one end of the room to the other, and while the view of Sam's ass was quite impressive even in the darkened room, this wasn't getting them anywhere.
“Sam. I'm topside, and we're together. Believe me, this is a hell of a lot better than the alternative.” He belatedly hoped Sam didn't pick up on his choice of words and lifted up the blankets pointedly. “Now would you come back to bed? We've got to head out early.”
Sam curled his hands into fists and stopped pacing. He blew out a breath and sat back down on the bed, looking for all the world like he still wanted to go try to tear an angel apart with his bare hands.
Dean grinned at him, sharp and wicked, as he sat up and turned to face him before swinging a leg across Sam so he was straddling his lap. “Yours.”
“Mine,” Sam agreed and leaned in to claim his mouth in a desperate kiss that was more like a battle of teeth and tongues. Dean reached one hand up to tangle in Sam's hair, keeping him held in place so he could return the kiss in kind. The other hand stroked Sam's hip, encouraging Sam to move against him. In this position, Dean was soon going to have a difficult time trying to stick to his plan of getting them on the road first thing in the morning.
Sam lowered his head and began to suck a bruise onto Dean's neck, marking his claim. He placed his palm over the handprint on Dean's arm and squeezed, almost to the point of pain, as if he could somehow make the mark his own. “Mine,” he growled.
“Always,” Dean said. He began thrusting his hips against Sam wantonly, desperately trying to gain more friction.
“Mine,” Sam repeated roughly, and surged forward to force his tongue between Dean's lips. Dean opened his mouth eagerly for him, willing to give him anything, everything, all of it. He couldn't have stopped this now even if he'd wanted to, and he really didn't want to. Sam's hands were roaming everywhere, often coming back to cover up that damned handprint, and he was looking at Dean with so much intensity that there was no way in Hell Dean was going to let him start something like this and not finish it.
Dean threw his head back and panted, “That's what I've been trying to tell you. You have nothing to worry about.”
“Then prove it.”
"Oh I will," Dean promised. They fell back onto the bed in a pile of sweaty limbs and tangled sheets.
Leave it to Sam to know a good opportunity when he saw one.