Possessed!Sammy could've killed Dean at the very beginning in the hotel room instead of knocking him out.

NODS! Total agreement on my part (as if Sam/Meg would miss the heart or the head when it was obvious he/she had much time to aim), I was going to talk about it but I'm still unsure of the exact circumstances to Meg's possession of Sam. I think Meg lied through her pretty teeth, sure, a huge part of it was all about revenge on her part. However, I think it is just the icing on the cake. I cannot imagine her not obeying the YED's orders. That last couple of scenes where Meg-as-Sam is laying into Dean she keeps on making comments about tests. What if it is just another test to see whether Dean would be useful? What if it was just something more to push Dean over the edge? I can imagine the YED telling Meg to hurt Dean (have some fun) but no death.

Ohhh, I didn't even think about the diner scene in that light (I was too stunned to make any sort of connection), but that makes perfect sense. I'm beginning to feel this urge to make a list of the times the YED could have killed Dean but didn't.

Ditto in relation to 2.01, though I am really curious about what the YED is/will be doing with John's soul. Yes, it could be as simple as revenge, but it just feels as if there's more.

In fact, the YED has reason NOT to take the deal and let Dean die because well. Dean did kill his son.

That's what I thought, I kept on thing that it was a major strategical error on the YED's part. If had really wanted Sam to turn into a cold blooded murderer it would had been much easier to kill off Dean, and let John and Sam go on a vengeance binge. I do believe that Sam would still want to do the right thing, but he was this close to killing his own father in the cabin, and it was Dean who reined him back.

Hmm, I just realised that the YED is in a win/win situation. Sam goes darkside - YED has powerful psychic soldier. Dean goes on vengeance spree - YED can possibly gain a soldier using John's soul, and possibly promises of a living Sam as an incentive. This, of course, it under the assumption that Dean has some sort of latent psychic ability.

In relation to the Colt - is it used to kill the YED, or does the YED needed to kill something? I'm still a bit confused on why the colt + bullet didn't kill the YED during 'Salvation'.

Thanks for reading!