that would explain him having no soul and also the flickering light at the end of season 5..
it would fit with how much demon blood Sam drank in Swan Song..remember in When the Levee Breaks Cas notes that drinking enough blood to kill Lilith would change someone forever and turn them into something that Dean would want to hunt and how in Lucifer Rising, when Sam does kill Lilith, his eyes started to go black like a demons? it was assumed in the 5th season God removed his cravings for it and hence the lack of side effects..but if God didn't raise Sam again in season 6 then whatever did probably wouldn't have bothered to cancel out the effects of the demon blood he drank to fight big ol' Lu..in fact, it may have wanted the effects to come out in Sam..whatever raised Sam wants him souless or at least cold and the alphas all together (or dead) for whatever reason..

Intersting theory. I kinda doubt it, since he's still human, but who knows? This IS Supernatural. Anything's possible.

I don't think so because it's not as though demons have no soul- they are made up of nothing but soul. It's been twisted and corrupted beyond repair but it is a soul.

Sam is a human shell; he has no soul. He can't feel anything- that's not very demon like. It's true that there may have been some side effects from the blood he drank when he became Lu...but unless he's been chugging it all year that should have run out by now. I suppose he could still be drinking it, but I don't know...He doesn't act like Sam hopped-up on demon blood to me. Of course the fact that he's emotionless might counteract some of the mental effects of the blood but...again, I don't know.

And it's nice to see a pick from you, lucy! I miss them. XD

*blushes* hey fanfly, nice to be here again :)

No, no, no... I don't want even to think of that sweet Sam will turn into demon!

I agree with @fanfly, he can't be becoming a demon can he? I mean they have souls, twisted and warped (like said above) but they are definitely there. Sammy isn't feeling anything, he has no soul right now so I think it has to be something else.