Throughout this season of Supernatural, there have been a lot of
depressing moments. Sam and Dean split up, Bobby wound up in a
wheelchair, the Colt didn't kill Lucifer, Ellen and Jo died, Bobby
wanted to kill himself, etc. But perhaps the most emotionally painful
one happened in "Dark Side of the Moon" when Dean threw away his
My Recap of "Dark Side of the Moon">>
If you're not familiar with the backstory, this might seem trivial, but
it's not. Originally intended as a gift for their dad, Sam gave Dean
the necklace as a Christmas present when they were young and it came to
represent the bond between the two, the way Dean was Sam's surrogate
father and protector. By throwing it away, Dean essentially threw away
his relationship with Sam. See Photos from This Episode>>
Why would he do this? We've seen the boys fight before, even go their separate ways, but Dean always kept the necklace. There are basically two ways of thinking about this.Dean Hates Sam
Obviously this is untrue, but let's follow the logic. In Heaven, Dean saw that all of Sam's best memories were his worst nightmares, moments when Sam left his family. One could argue that seeing Sam's true feelings about family made Dean realize that he's been wasting his life trying to look after him if this is what he gets in return.
If you believe that, I have a bridge in Brooklyn I'd like to sell you. The truth is that you can't stop loving family. Dean may not like his brother and he may fight with him, but he will always love him. So why did he throw away the most cherished present his little brother ever gave him?Dean is Preparing Himself
Simply put, Dean is at the end of the line. He's spent the entire season trying to find glimmers of hope in the battle with Lucifer. First it was the Colt, then it was God. "My Bloody Valentine" ended with a teary Dean begging God for help because he couldn't stop the Apocalypse on his own.
The conversation with Joshua in the Garden was a rude awakening. Dean discovered that his last and only chance for help won't do anything. But rather than get depressed, Dean simply took this information in and is now preparing himself for the only way out: he has to say "Yes."
It really is that simple. Dean has exhausted every possible alternative and now even he realizes that saying "Yes" to Michael is the only viable option. He may not be able to admit it yet, he may not even know he's made this decision, but it's the only explanation I have for why he threw away the necklace.
If he knows that he'll say "Yes" and that he may have to kill his own brother, the only way Dean can cope with it is to push his brother away first. He's trying to distance himself emotionally from Sam so that he can be strong enough to say "Yes." It's the only way out.(Image courtesy of the CW)