Silence is Golden

This sets place after the ending of the episode "Sex & Violence" in season four.
Bobby just drove off, leaving the brothers alone to face the consequences of their fight earlier.

…

They tried to pretend that everything was okay, but both of them knew they could never go back now. Siren or no siren, that fight was coming either way, but it did not make it less painful.
Dean felt betrayed by Sam, but it was not the lying or that he was hiding things from him. It was what he had said about his time in hell. He had bared his soul for Sam and he threw it back in his face. It filled Dean with so many emotions at the same time, he could not really make out which one was the strongest. He thought it might be fear.
Sammy was gone. He looked and sounded like him, but the thing inside him was no longer Dean's dorky little brother. It was something so sinister and so dark. Dean's heart was breaking as he felt that whatever little hope he might have had left vanished the second Sam said that stupid line.
"Bohoo..."

Dean opened and closed his fists while breathing through his nose. Sam was looking down where he was kicking at some pebbles on the ground. They both stood leaning on the passenger's side of the car and neither of them wanted to talk.
What could they possibly talk about anyway?
All his life Dean had fought for Sam, everything he had ever done had been for Sam. He had thrown away every opportunity of happiness, knowing that if he ever stopped living like this, he would not be with Sam. As sad as it was, hunting had been the one thing that had bonded the two and the realization of Sam's true feelings made Dean feel like he had been woken from a slumber.

"I think..." he started. "I think I need to go for a drive."
"Okay." Sam sounded confused. "Let's go then."
"I mean, on my own Sam." Dean looked at Sam and could barely believe those words came out of his own mouth. It was as if someone else was in control of his speech, yet he did not take it back.
Sam looked surprised, was it really that hard to understand?
"Uhm...okay, just drop me off at the motel and we'll catch up later."
"No Sammy...I mean Sam."
Sam chuckled at this. "Okay, so, what, now it's just back to Sam?"
"Yeah, I guess so." Dean shrugged his shoulders. "What I'm trying to say is, I'll drop you off at the motel, but I won't be coming back for you."
"Right. For how long?" Sam almost seemed annoyed.
"No Sam, I won't be coming back."

Something in Dean's voice changed with that sentence and now he could see that Sam understood what he meant.
"So, what, you're breaking up with me?" Sam's attempt to joke did not go well with the situation and he was obviously upset.
"It's like you said, I'm holding you back, so I won't do that anymore."
"Dean, come on, that was the siren's venom talking, that wasn't me!"
"Yes it was." Dean locked his eyes on Sam's. "It was and you know it. All this time I was afraid to tell you the truth, afraid that you would judge me. Then I thought, hey he's my brother, and I can trust him. Turns out I couldn't."
"Dean..."
"Don't even...." Dean was chewing at his lower lip. "You can't take it back and I can't be around you anymore. I don't know you and it's clear that you don't want anything to do with me, so just get in the car so I can drive you back."
"Dean! Come on man!" Sam's voice was cracking up, there was a slight hint of panic in it.
Dean did not answer, he just walked around the car, opened the door to slide into the driver's seat and started the engine. Sam quickly turned around and opened the door to the passenger's seat and got in.

Once inside the car, Sam turned to Dean. "Dude, come on, let's talk about this!"
"We have nothing more to talk about Sam, nothing what so freaking ever, you got it!"
When they reached the motel, Dean almost threw himself over Sam's legs to open the passenger door.
"Out."
He did not even look at Sam as he slowly made his way out of the car.
"Dean...please!"
He closed the door after Sam and drove off with a violent screech. He had seen Sam's tears, but ignored them.

When he had driven out of sight of Sam he could not hold it in any longer and had to pull the car over to the side of the road.
He shut off the engine and his head fell onto his hands, still clutching the steering wheel and he started to cry. Tears were streaming down his face and dripping down on his lap. It was as if all the sadness he had ever felt came down on him at the same time and he cried so loud it felt like his lungs would implode.
He started beating the steering wheel, then the dashboard, his fists going all over the place and ended with him screaming his heart out.

When he woke up it was dark. He realized he had fallen asleep in the car during his breakdown. His head was killing him and he tasted the salt from his tears as he licked his lips. Those first seconds were blissful, since he could not remember what he was doing there. It did not last long and he felt his stomach churn.
Ignoring his heart screaming for him to go back, he turned the key to the car and woke the Impala from its mutual slumber. He drove off into the darkness, not knowing where he was going.

He did not care anymore; he had nothing left worth fighting for.