He looks at Sam and wonders 'is this really my brother?'. It's not the first time...nowhere even close to the first time, but as Dean watches Sam work he has to think it once again. Dean got his answer a couple months back. He knows that the person sitting on the other twin bed in the dingy little motel room is, in fact, his brother...just missing a soul, but Dean isn't so sure that that's the whole story. He's having a hard time believing that one tiny soul is responsible for making his brother who he is.
It seems insane, really, that after all they've been through...all they've seen, he still finds it hard to believe that a soul holds so much importance, but Hell did a lot more than just shake his self-confidence and trust in the rest of the world. It made Dean realize that there's absolutely no end to the things that can tear the two of them apart. Dean often wonders if maybe it's not just Sam's soul that's missing. He knows that the demons and angles have all said that souls hold a certain significance, but it's still difficult for him to wrap his head around the idea that Sam is only Sammy because of something as simple as a soul.
It just all seems far too easy. It can't possibly be as simple as take away one little soul and suddenly you have a sociopath on your hands. Dean can't even really explain his problem with the whole scenario...well, beyond the obvious. He should be happy that the situation apparently boils down to getting Sam's soul back equals getting his little brother back, but it just feels wrong. It feels like, especially after everything they've been through, that it's just too easy of an out. There has to be something else...something they're all too blind to see...something that they're missing. Dean's almost completely sure of it, and he's almost equally as sure that he's missing it because he's too busy running around being Sam's conscience.
When Dean promised their father that he would look out for Sammy he never knew that he'd have to be the kid's Jiminy Cricket, and it's really starting to get to him. It probably wouldn't bother him as much if Sam slept, but since he doesn't, Dean just spends his nights dreaming of the terrible things that Sam could be doing while Dean unfortunately has to rest. He's already sleeping as little as humanly possible that way he can watch Sam as much as he can without passing out due to sleep deprivation. Dean knows it's not actually doing either of them any good, especially since he's starting to wonder what this Sam is willing to do when Dean becomes no longer necessary...when his need for sleep and other such worldly desires becomes too much for Sam to deal with, and soulless Sam 'realizes' that he's better off without Dean. He wonders what will happen the moment that he is no longer useful to Sam.
If someone had asked Dean six months ago if he thought that Sam would ever be capable of killing him Dean would have laughed in their face and said 'no way in hell,' but that was six months ago. Now? Now, he's not so sure. Hell, he's not even sure if the guy sitting on the other bed is his brother anymore. Sometimes Sam stares at him, and Dean can't even see a glimmer of his younger brother. Sometimes he asks questions about what people with souls do, and it makes Dean ache inside, because his brother...his Sammy never had to ask those types of questions. Sometimes Sam looks him straight in the eyes, and all Dean sees is an empty shell of someone who could have maybe been his brother at some point, but sure as hell isn't now.
Dean worries a hell of a lot about whether or not if getting Sam's soul back will be enough to get his brother back. He worries about what Sammy...the real Sammy-with soul intact-will do once he get his soul back. How he'll deal with everything that he's done...everything that he's willing to do without his soul. Sam told him that he's killed innocent people while doing this job, which isn't all that hard to believe with the way that soulless Sam looks at him, but Dean isn't sure how his little brother is going to deal with that once he has his soul back...once he's able to feel guilt again.
And that's just one more thing that has been eating away at Dean. What if getting Sam's soul back just tears his little brother apart? It's not like Dean knows everything that Sam did while he was on his own for an entire year with no one looking out for his well being. He knows snippets, but that's mainly because he couldn't get Sam to shut up. Dean isn't sure that he can handle hearing how far his little brother has fallen. It's hard enough for him to deal with the obvious changes right in front of him, and Dean doesn't even bother to think about how far Sam's come from the little kid that he used to make spaghettios for, because that's just a deep heart wrenching agony that he doesn't need to remind himself of...ever.
He knows that it doesn't matter though, because Dean's stuck with this soulless husk of his little brother until they somehow manage to get Sam's soul back...not that either of them have a single clue about how to do that. Dean's not even sure if Sam wants to get his soul back. He just seems to be so comfortable with being soulless...so damn happy, and it's been so long since he's seen Sammy happy. Dean almost feels guilty about needing to get Sam's soul back, especially when he isn't even sure that it's for the best. Sure, less innocent people will die in the line of duty, but Sam is a better hunter now-at least, if Dean ignores his lack of instinct and lack of empathy-but he gets the job done no matter what, and sometimes...more times than Dean likes to admit he thinks that maybe their father would have been okay with the way that Sam is now.
And it hurts to think that he's the only one hellbent on getting Sam's soul back. Dean isn't sure if that's because he misses who Sammy was, or if he misses being the one that was held back instead of being the one holding back more. It's exhausting having to watch every step he makes as well as Sam's every move. He's just so damn sick of having to explain why Sam needs empathy, and why he can't just go around not giving a damn about the people they are supposed to be helping. He doesn't know how the hell Sam dealt with him for as long as he did, because, while Dean knows that he was never as bad as soulless Sam, he also knows that it still wasn't any kind of picnic for Sam to try and keep Dean from getting lost in trying to put down the monster in the night.
Still none of it changes anything, really. Dean knows that without a doubt. He knows that no matter what he'll stick with Sam. It doesn't matter how cold his eyes can be...how emotionless he truly is...how watching him clutch a gun anywhere near the vicinity of innocent people makes Dean's skin crawl, because, even without a soul, Sam is still his little brother. At least, he hopes that's true. It's not like he has a lot to go on here, but for once Dean is just going to hope for the best, because even if the guy sitting on the bed next to his isn't his Sammy he's wearing Sammy's meat suit, and Dean is going to do whatever he has to in order to get the real Sammy back. That's something he can always count on, because it's not a promise he'll ever have to think twice about making. If Sam is in trouble Dean will be there, because living with the alternative just isn't an option...not ever.
The End