It's sad, in a way.
No one can see, they don't look deep enough. They see the happy exterior, the smiling and loving man who can't possibly be frayed at the edges, coming undone at the seams. This man must have it all together.
In truth Dean can't really remember a time after Purgatory where he walked passed somebody and didn't have his guard up. He was ready to defend in a millisecond, always on edge. Expecting a surprise attack became second nature.
Always, always, there was that soft whisper in his head, telling him that this was all a dream. He'd wake up on the mulch ground of Purgatory, listening to the howls of creatures and Benny's snoring. If he woke up there, he knew he wouldn't have found Cas. He'd still be traveling farther from Dean, trying to keep him safe.
Dean could be in a sea of people, light, and sound and still have that frightening whisper lulling him into a day dream. He couldn't escape, no matter how hard he worked against the current. That whisper would always win.
He's always zoning out, it seemed, falling into memories he wished he could forget. That's all he wanted, was to forget, and perhaps be forgotten. He didn't need the world to know his name or story, sometime he just wanted to drift away on that sea of light and sound.
This feeling, it's something Dean returns to when he's lost. When he feels so low that the only that can possibly bring him back up is the click of a trigger.
No, that's not right.
The only thing that could keep his from wanting that sweet, terrifying sound of a trigger is Cas.
When he's lost and seemingly so alone, Dean talks to Cas. Mostly when he's gone because face to face confessions are much more personal, that much harder. So when Cas leaves, rarely enough, Dean prays to him, sending his thoughts and worries on wavelengths of air and sound.
Cas listens and never says a word when he gets home, knowing it'd just make Dean uncomfortable. He would have said something if he believed it wasn't working for Dean, but it was. He looked significantly improved when Cas returned home each time. All his woes and worries were being lifted.
And he just kept getting better.
The nightmares made less of a return, his little daydream spells vanished. His smiles and laughs even grew genuine outside the comforts of the bunker. That barrier Purgatory had built up, a cage for anything good in Dean's life, was slowly coming to a crumble.