Castiel proposed the theory that Sam's soul is still trapped in the cave Lucifer and Dean bring the question "Is he even still Sam?" Is it only the body of Sam, with all, that memories of thoughts and behavior?
Is a kind of "zombie Sam", a walk wearing face If they managed to take the soul of Sam and restore it to its body, will benefit the soul of all the memories Sam running? Or will his spirit just took over the body again with all the knowledge trapped in a cage for a year in the period of the earth?
After long last Sam managed to free themselves from the bonds and basically Dean said that he had no choice but to continue working with him. To encourage a feeling of goodwill, Sam agreed to try and help the Dean to take his soul. But the only lead they have is Samuel. So the grandfather's house they go. When they arrived, they basically find a mini-army has taken residence in his barn. Castiel's work in Samuel's mojo and stated that he has a soul. Which things are beginning to get interesting, because I wonder "How did Samuel do the things he did while having a soul? At times, he acted even sketchier of Sam". But we'll get it too. Castiel back to fight a civil war in Heaven (after giving Dean a little snark while noting that he was not the only one with problems) and Sam quickly realizes that Samuel is mobilizing its people to catch vampire alpha. Dean wanted and, although he and Samuel certainly did not trust each other, Samuel agreed to let him come, as long as Dean to follow his orders.
This group went to the house where the alpha vampire hiding. Samuel command Gwen and Dean stayed while others went inside. of course, Dean, ignoring his orders and eventually (after realizing it was the home of vampires alpha vision when he turned around), look at this group (including Sam) spiriting alpha vampire into the back of the van. Before that, he comes across a lot of vampires was beheaded in the courtyard. He was surprised when driving after leaving the house alpha's, Dean will be very angry when Sam lies to him about what happened at the complex, so that he faced
him with what he knows. Sam recognized that Samuel was to collect and tortured all manner of monsters (including Alpha), but he did not know why. Dean takes control, Sam said that if they would work together, then he will be responsible and Sam will have to tell him everything because of His judgments now seriously questioned.