Sam to turn dark?

Throughout the entirity of the show the question has been looming will Sam turn? will he give into the demon blood and the offers of power and turn fulltime darkside or will he stand by Dean and fight the good fight till the end?

Well it seems to me that this season is the one that'll answer this big question, what with the arrival of the angels, the warriors from god, and the bigger and badder demons coming out to play and the ultimate battle that will commence should the demons succeed in raising luicifer. The brothers have been Pushed so hard and the bond between them is beginning to strain as they're both keeping more and more secrets from eachother since Deans return from the pit.

In Deans absence Sam took a notable turn for the worst becoming suicidle in his hunting attemps and even going against Deans last wish that he not use his psychic powers, Is this a foreboding of events to come will Sam continue to disobey his brothers wishes?

However since their touching moment in Heaven and Hell and Sam revealing the truth to Dean in previous episodes they are a tad closer to the old Sam and Dean we knew and loved. But is this enough? will Sam stick with Dean or will the temptations of his powers be too much for him?

Ultimately will the brothers have to face eachother in a hunt, Dean the warrior from God, and Sam the boy king of Demons....

What do you think?