Dean doesn't talk sometimes. But that's okay, because he can handle this all on his own.
The first time that it happens is when his mother dies. When he sees her die. He doesn't see much. Just a fleeting glimpse of her on the ceiling as he runs outside with his baby brother grasped in his arms. But it's just enough for it to be burned into his mind forever.
He can't figure out why he can't talk, just that he wants to, but that every single time he goes to open his mouth and begin to speak the words die out before he can force a mere syllable out. So instead he just sits there, focusing on Sammy instead of speaking up.
If it bothers John, he doesn't show it. Just stares out the window with a bottle in his hand. Although sometimes Dean thinks that he can see his dad start to say something to him, but he doesn't, so Dean begins to think that he was just imagining all of it.
Two and a half months passes by. And eventually Dean begins speaking again. At first with just some small whispered assurances to his brother as he lays sleeping in his crib. Then he starts saying things to John, and other people when they are around him.
The first time that he speaks to John again, his father smiles at him and pats him on his shoulder. "Knew you could do it, son."
Dean smiles at his father and says in a small voice that he doubts his father can hear "Me, too, Dad."
Six years has passed, and the incident has long been forgotten. At least until a stupid shtriga comes into the motel room that they're staying in and decides to make his little brother its next victim and it's all his fault it's all his fault it's all his fault. John berates him for it and Dean says that he's sorry. He tries to say that it won't ever happen again. That he'll do better next time. But his throat closes up on him and all that he gets out is a grunt.
The next morning Dean hurriedly packs his and Sam's bag while John goes and gives their room key back. His hands shake as he fiddles with the bags, nearly causing them to fall over off the bed and spill all its contents onto the floor where he'll be left to pick it all up again.
"Dean? Dean, what's going on." Sam asks, worry evident in his voice. "Did I do something wrong?"
Dean wishes that he could stop what he was doing and assure his brother that no Sammy you didn't do anything wrong. It was my fault. I didn't listen and you almost paid the price. But he can't. So instead he just looks up and smiles at his brother, hoping to convey without words that everything was fine. That small action seems to relax Sam a little bit, since by the time that dad comes back he has stopped pouting and his shoulders are no longer tensed up.
John takes him and Sam up to Pastor Jim's while he goes and tries to kill that stupid shtriga. Whilst he's there, Pastor Jim will talk to Dean. Telling him that it's all right. That it's not his fault. That everyone makes mistakes, and it will feel better if Dean would just talk to him. And somehow the worry and concern in Jim's voice is even worse than his father's apathy. Because it makes Dean wish even more that he'll just start talking again and laugh and joke that of course everything was all right. After all, why wouldn't it be? Jim wraps his arms around him, and Dean stiffens before falling into the embrace, eyes stinging with tears.
A week later John comes back, stomping his way into the house as Dean watches Sam color a picture. "Damn thing was gone by the time I got back. I waited, but it never showed back up."
Guilt washes over Dean once again, and he says as loud as he can in his raspy voice, "I'm sorry dad."
John ignores him.
Sam is gone. Just left after telling Dean and John that he was going off to college and was going to live his own life from now on. He didn't go quietly. There was a lot of screaming and yelling from everyone in the room with all of it culminating in John grabbing Sam by the shoulder's and tossing him out into the street.
Dean runs out after him. But Sam is already walking away to the nearest bus station and Dean tries to call out to him but he can't and he tries so hard to yell at his brother to get back here but nothing comes out.
And now Dean is sitting in the driver's seat of the Impala while John drinks himself into unconsciousness and Dean is fiddling with the keys in his hand trying to work up the courage to go and find his brother and drag him back here. But the furthest he gets to actually doing the deed is inserting the keys into the ignition and starting the car.
It's nearly midnight by the time Dean walks back into the hotel room to find John passed out on one of the bed, beer bottle still grasped in his hand.
Dean climbs into the other bed, not even bothering to pull off his clothes. He curls up and tries to fall asleep but it doesn't come until the smallest hints of light begin poking through the curtains and he can hear his dad beginning to toss and turn more as he started to wake up.
Dean and John begin to go back into a routine- well, as much as a routine as it can be- with them traveling all around the country hunting for monsters and killing them once they found them. Sometimes when John is really drunk he'll yell at Dean to get off of his high horse and to say something Damn it. But Dean can't speak. He can't and he doesn't know why.
All in all, it takes up to four months for Dean to start speaking again. It's the longest he has gone without speaking since Mary died. He tries not to dwell on that fact.
It's been nearly six months since his deal, and it's just now occurring to him that he's dying and he's going to hell and he's going to leave Sam all alone. He supposes that that has something to do with him fighting off that dream version of himself.
Sam keeps trying to tell him that everything we'll be all right and that they'll find out something to reverse this mess. But Dean knows better now. He's going to die and there's nothing that they can do about it.
Sam is frantic. Scouring book after book in search of something that will save Dean. But Dean knows that nothing will work and so he just sits quietly looking at his brother as he presses two fingers to the inside of his wrist to get the assurance that at least now he's still alive.
This goes on for a few days and finally it seems as though Sam has had enough and he stands over Dean as he's sitting on a bed and he asks him why he isn't talking. Dean just shrugs his shoulders and shakes his head as Sam sits down beside of him and hugs him.
Sometimes things happen and Dean will stop speaking again. Sometimes they only last for a day or two, and sometimes for weeks on end. But eventually he does start speaking again and Sam waits patiently for him to do so. He never tells Sam exactly why he doesn't speak, because to be honest he doesn't quite know himself. But Sam never even really asks about it again. And whenever it does happen again him and Dean form more silent ways of communicating that turns out to work very well.
Dean doesn't talk sometimes. But that's okay, because he's got friends and family that are willing to look out after him.