I'm still re-watching SPN season 9. I just finished The Purge. I have to say, Sam and Dean's conversations at the end of Sharp Teeth and The Purge don't make a lot of sense to me. It's clear that Sam is very upset about the Gadreel situation, but it is not clear what, specifically, he is most upset about. He seems to equate Dean tricking him into being possessed with Gadreel to Dean talking him out the trials - two very different things. The conversations are very strange, and not very well-written.
But - Jared Padalecki acts the hell out of it. It drives me crazy when people talk about how mean Sam is in these conversations, because just his face watching Dean at the end of Road Trip and at other points is so empathetic. He's upset with Dean, but he still sympathizes with Dean.
And I still think Dean suggested killing Maritza in The Purge for no other reason than to mess with Sam.