Supernatural - What's Wrong With Sam?

The below is all speculation.

I rather liked the "Sam is still Lucifer's Vesel" theory until the "Third Man" episode as I think Castiel would mention that to Dean, no matter how rusty his people skills are, especially given Cass' position on resuming the path to Armageddon.

I'm assuming Sam is Sam, otherwise this whole season is rather a cheat.

1.Sam hurt/abandoned/killed Adam while in the cage, possibly to earn his release. The guilt is eating him alive and he can't confess to anyone, particularly not Samuel and Dean as both would find hurting family extremely abhorrent, especially Dean in the context of Sam hurting their younger brother. Sam is once again intent on becoming the best hunter in the world in act of penance. (His current behavior, including the obsession with hunting and willingness to sacrifice people, is rather similar to his behavior in "Mystery Spot" after Dean's final death). Sam is subconsciously hurting Dean because of his presumed inability to forgive Sam the unforgivable.

2. Through a Hell time paradox (time works different down there), Sam was one of the souls or the only soul Dean tortured on the rack. Explains why Sam didn't want Dean around and is willing to risk Dean's life so casually. Would explain Sam's personality issues around Dean and why he spilled the beans to the Campbells about Dean being a torturer in Hell.

3. Sam still has "demon vision" from the pit and Dean is at least partially, if not completely, a demon. Explains why Sam didn't want Dean around and is willing to risk Dean's life so casually.

4. 2 & 3

5. Dean never made it out of Hell.

6. Dean's been in a psychiatric hospital since Sam died in season 2.

7. End of the series reveals it was all Dean's hallucinations since John left him alone and he went off his meds.

8. Dean's been catatonic or suffering delusions since Mary or Sam died in a house fire Dean lit when he was four.