If the demon came out of hell in order to seek revenge then does that mean John can too?
Corollary: What is the point of sending your enemy to hell if he's just going to crawl out six months later and seek revenge???
The demon had possession of Sam's body, so why not just...throw if off a cliff? Or, shoot for Dean's heart instead of his shoulder? There has to be a reason the demon was trying to goad Dean into killing Sam. Because it's a greater sacrifice? Purely for the angst factor? Or maybe because Dean is the only one who actually CAN do it? Maybe Sam is protected against any other version of death (i.e. the Croatoan virus.) Maybe Dean is literally the only thing that can end Sam's life...or save it. As the case may be.
On January 15 I did a post about Sam drinking a lot this season and conjectured that it mattered to the plot. To add to that...he's sloshed in Playthings, obviously. He and Dean both drink (from the flask, Sam also says "Dude, I don't want a drink!") in Houses of the Holy and beer figures into Born Under a Bad Sign twice....once when Sam demands a beer from Jo and again with Bobby's dosed beer.
Important or coincidence?
Speaking of important or coincidence....Dean's flask. All of a sudden, it's like a new character! It's popping up everywhere! In several episodes Dean has been shown drinking out of it or offering it to Sam. In Bad Sign, they even did a cut-away close-up shot of it when Dean gets tossed around by evil!Sam and it falls out of his pocket.
Why so much focus on the flask? Will it come into play later? Am I just distracted by boredom? WHAT DOES IT ALL MEAN?