I think Dean has learned his lesson. Just my take on it before Kripke actually gets out the duct tape.
Come Together
The road seemed to disappear under the wheels of the Impala, dotted yellow lines blending together to form one continuous arrow pointing nowhere. Dean rubbed his face, forcing his eyes to remain open, alert for any sign of a town in the darkness. He knew he needed to pull over soon and, with the temperature beginning to plummet at night, didn't really relish spending another night in the car or, for that matter, in another abandoned farmhouse complete with cold draft with much too curious nocturnal inhabitants. He wanted a real bed in a real motel with a real heater and a real lock on the door.
He was tired.
Tired of having to keep his guard up 24/7, tired of never being able to truly give in to his body's need for rest. He'd hunted by himself before, never really thinking about being alone, always knowing that Dad or Sam or Bobby was just a phone call away. But that was no longer the case. Dad was gone, Bobby had his own problems to deal with and Sam….
He missed having someone to bat ideas back and forth with. He missed not having someone to help with the driving. He missed not being able to just open his mouth and blurt out something, knowing there'd be a response – welcome or not. Cas had been a suitable distraction for a while, but…
He missed his brother.
It had taken him a while to admit it, but despite everything they'd been through, Dean couldn't help but miss what they'd grown accustomed to.
But he wasn't really sure he was ready to go back.
Despite the pang of regret he felt whenever his eyes drifted to the empty passenger seat, he just hadn't been able to come to terms with everything that had happened. The problem wasn't that Sam had killed Lilith by using his powers and allowed Lucifer to rise -- Dean wasn't that much of a hypocrite. He knew this whole thing was his own fault. Although he'd had no idea that accepting Alistair's offer would jump start the apocalypse, he wasn't about to let himself off the hook for what he'd done.
He'd broken the first seal.
Him. Dean Winchester. Nobody else could take the blame for that; it was all on him. So, whatever Sam had done, really, in the whole scheme of things, was just icing on the cake. Dean didn't blame him for any of it. He'd been trying to do something good. He'd made a bad decision in trusting Ruby, but again, Dean hadn't been around to stop it, so he couldn't really blame the kid for falling into her clutches.
But he'd been brought back from Hell. Sam's need to make Lilith pay should've been over. He'd promised to stop.
He lied.
Even when confronted, Sam had continued to lie right to Dean's face. How do you continue to trust someone when you both know that trust is broken? Sam should've known better. Hell, Dean was pretty sure he had known better, but he went right ahead and did it anyway.
And even after Lucifer rose, and Sam realized he'd been nothing but a pawn in Ruby's plan, he still couldn't admit he had a problem – not until he was confronted with it in that convenience store. When Dean had seen the look on his brother's face as he eyed what he believed was demon blood on that knife, Dean had known. Sam wasn't okay.
It had just taken Sam a little longer to realize it on his own.
But, he had. And Dean had watched his brother walk away.
It was for the best. Sam had been right, he couldn't hunt this way. He couldn't put himself out there when neither of them knew how he'd react. The stakes were higher than ever, and they couldn't afford any missteps. And, Dean had to admit, not having to worry about his brother these past weeks had been a relief. For the first time in his life, he wasn't responsible for anyone but himself. And that actually felt good.
He hadn't lied to Castiel. He was actually good.
But that didn't mean he didn't miss his brother.
The phone vibrated in his pocket and he shifted on the seat as he reached a hand into his jacket to retrieve the device. His breath caught in his throat as he glanced at the caller I.D.
Speak of the devil.
Taking a deep gulp of air, he blew it out slowly as he opened the phone and placed it to his ear.
"Hey, Sammy."
"Dean. Hey." The familiar voice was hesitant, as if not sure what reception to expect. "You driving?"
"Yeah, open road and everything." Dean paused a moment, not sure what to say. "You okay?" He winced as he realized the familiar concern was still close to the surface.
"Yeah," came the too-quick reply. "I'm…, yeah. I'm okay."
"Good." Dean's brow creased as he listened to the breathy sound of his brother's voice. Sam's voice always rose a bit and thinned when he was trying to hide something and Dean felt his concern notch higher. "Glad to hear it. Bobby says you got a real job."
"Uh, yeah. Working in a bar. Seemed like a good place to lay low for a while."
Dean nodded, forgetting that no one was there to see it.
"So, uh… you okay? Haven't heard from you for a while."
Dean shrugged. "I'm good. You know, keeping moving, keeping busy. Lots of things to kill."
"Right. Uh, look Dean… where are you?"
Dean's frown deepened as he struggled with what to say. He didn't have any reason to hide anything from Sam, but something inside of him was hesitant to reveal anything. He'd finally started to feel comfortable alone, and for some reason, he was feeling protective of that.
"Somewhere near Kansas City," he finally admitted. "I've been looking for a place to crash for the last twenty minutes. Nothing but a lot of empty nothing out here."
"I can meet you there tomorrow."
"What? Uh, wait, Sam. " He fumbled the phone, finally seeing an exit and pulling off the highway. "Meet me? I'm not sure… why? What's wrong?"
"Nothing." Again, the reply came too quickly. "I just... We need to talk, Dean."
Dean sighed. "I know, Sammy. And I want to talk to you, it's just…."
"What?"
Dean flinched at the edge of anger in his brother's voice.
"I'm tired, Sam. I've been driving sixteen hours, I'm hungry, I'm edgy, I'm just…"
"Sounds pretty normal for you."
Dean snorted a laugh at the unexpected comment. "Yeah, I guess. I just… I need some time, Sammy. I need to think."
Sam's frustration was palpable even through the phone. "Dean, it's been weeks. What have you been doing all this time?"
"Honestly? Anything and everything I could to avoid thinking." He pulled off the road into the parking lot of a run down motel, stopping the big Chevy next to the blinking vacancy sign near the front office. "Look, Sammy. I just need some sleep. I swear. I call you in the morning and we'll talk. Okay?"
He held his breath until he heard his brother's soft sigh on the other end of the line. "Yeah. Okay. It can wait. Get some sleep, man, huh?"
"That's the plan." Dean paused, finding that his brother's voice had filled a hole he'd been trying hard to ignore. "I'll talk to you in the morning, Sam."
"Yeah. Okay." Silence filled the space between them, but Dean found himself not wanting to sever the connection. "Be careful, Dean."
"You too, Sammy."
"Night." With that final word, the call ended and Dean slowly closed his phone, dropping it to his lap as he leaned his head forward and closed his eyes. He had no idea what to do.
He had angels hounding him, demons gunning for him, and the fate of the entire world resting on his shoulders. He'd managed to keep moving, he'd managed to avoid, but he knew he couldn't go on like this much longer. This weight was far too heavy to shoulder alone and, no matter how hard he tried, he knew he wouldn't be able to shoulder it forever. God help him, but he still needed his brother. He wasn't sure about anything anymore. He'd tried to convince himself he was better off on his own and he'd thought he'd been doing okay. He'd thought he'd built those walls back up stronger and higher than ever. And all it had taken was one phone call to crumble it all to the ground. All it had taken was the sound of Sam's voice for the first time since he'd watched him walk away in Colorado, and Dean was pretty sure he didn't want to do any of it alone.
The End