Dean died a few weeks ago, killed while hunting a vampire. The thing changed him, but didn't kill him. Dean begged Sam to kill him, even if Sam didn't want to. Sam knew Dean would do it himself if he didn't. So he had, regardless of how he would feel.
He didn't want to salt and burn Dean like most hunters had done. Sam wanted to be able to visit Dean anytime he wanted. Which he did. The little brother visited the older brother daily. He'd telling how much he missed him; what he'd been up to that day. Anything and everything Sam could think of.
Dean was always there, watching Sam. He loved seeing his little brother even if in the worst of circumstances. He knew his brother would be back daily, Dean would even wait out by his gravestone for his baby brother to come see him. He missed being able to joke and laugh with Sam instead of his brother doing it all himself.
He would laugh when his brother told jokes,and would be unbearably sad, but unable to cry when his brother left. Dean would watch as his brother slowly faded out of sight in the distance. As Sam left for the night, Dean would go back and sit with his back to his tombstones and wait for tomorrow.
He dreaded being alone, but he preferred it than finding other ghosts. Dean knew he was a ghost, and it scared him. He'd watch Sam grow old if he kept visiting, and he'd eventually stop visiting eventually. Dean knew it we just didn't want to accept it. He didn't was to face the fact that Sam would eventually forget about him.
The next day passed and Sam was nowhere to be found. Yet Dean still waited patiently. Had he forgotten about Dean already? It hadn't even been a month Dean thought to himself. He stayed past dark waiting to see if Sam would show up. He never did, and Dean felt so alone.
The following day Sam showed up, and sat down next to the Dean's tombstone, unknowingly setting next to Dean. "I miss you Dean. I'm sorry I wasn't here yesterday I got held up in a fight and got a bit roughed up. I wish you were here to tell me it was okay." Sam's voice faded off as he said it. He knew he was being stupid trying to talk to Dean when Dean was dead.
He stayed until nightfall, watching the sunset with Dean sitting next to him like they did as children. The thought made Dean smile, even if this was was a much sadder ending. He was glad it had been him and not Sam, he wouldn't be able to bare losing his Sammy.
He knew Sam was sad but he didn't know to what extent. Not even Sam himself knew. Sam had tried to get Dean back, selling his soul, making deal. Nothing worked, they all turned him down. He was all alone, and Dean was coming back this time. This time he was stuck with no place to go.
When Sam finally got his bearings together, he got up and stalked away without another word and without looking back. Dean stayed sitting against his tombstone, really and willing for the next day when Sam would return.
The next day there was no Sam, yet Dean still waited patiently. The following day there was also no Sam. Dean started questioning if Sam had finally given up on the ghost mojo, and moved on with his life. He no longer had to be a hunter, so why would he stay in the past?
Weeks passed, and there was still no Sam. Then one day still still sitting at his tombstone, patiently waiting his little brother's return, he seen Sam. He jumped to his feet grinning. So Sam was back, and hadn't given up on him. The thought made Dean smile. He was irresistible.
Dean waved out of habit to his little brother. He stood shocked when Sam waved in return. How could Sam see him when he hadn't seen him all those weeks before? Dean looked around wondering is Sammy was waking to someone or something behind him, but there was nothing.
When Sam finally reached Dean he pulled his elder brother into a tight hug. "I missed you Dean!" he cried as he pulled his brother closer, as if scared to let him go again.
"How can you see me? How can you touch me how - Are you dead?" Dean asked panicking. He couldn't be dead! He promised Dean he'd take care of himself, and not off himself. So what happened? Was this a joke?
"I think I am Dean, but it's okay because we're together now." Sam said hugging his brother once again.