I can't help think that if it wasn't for that final scene this episode would have been a bit so-so for me. I mean, it was solid enough (as in the structure and character notes), but it's so damn difficult to figure out their focus this season that I'm finding if difficult to be thoroughly invested (or maybe that's just the way I'm watching the show atm). I wasn't exactly riveted throughout the episode but by the end I could see how the story worked and felt more satisfied (and heartbroken).
As always, Berens writes great character pieces. This episode was focused on Mary and considering the hard task he had to achieve (her departure) I thought he did a pretty good job. Crappy thing to have to do (and I'm not sure why she had to leave so soon?), but someone had to do it (and I'm glad it was him and not that awful Duo).
The most powerful thing about the episode was the repeated theme of abandonment for both Sam and Dean. I am sure Mary will be questioned by many for her actions, but I think this works in the consistent theme of the Supernatural. Mary is no longer an idolised memory for Dean (and Sam - even though he's never really met her), but a real person - flaws and all. Something that comes up time and again for ALL the Winchesters is their flaws. We might feel that there's no way a mother could walk away from her sons, but we're taking about a Winchester here - so yeah. In order to tell the angst-filled story (including all the man pain), we have to have these wonderfully flawed characters.
And actually Mary's departure did make sense to me. I think mothers can love their children but still feel that they don't fit into their lives or need to "find" themselves in order to feel they can be better mothers. I like the layer it adds to her character - a person not just a mother. I think it's hard for us to imagine Mary, only yesterday, thinking of Sam as a baby and Dean as a 4 year old. This Dean and Sam must feel like complete strangers to her. I also think it mirrors John as a father maybe - clearly loved his children but had an interesting way of showing it.
The final scene was beautifully acted. Sam Smith brings a wonderful quality to all her scenes (I even teared a little in her scene with Castiel). Jared and Jensen's performances were absolutely gut wrenching.
The biggest problem for me is the way they've started this season. Having two episodes of Sam being psychically and mentally tortured and then having almost zero follow up troubles me (of course, I'm not surprised but it leaves this kind of elephant in the room feeling and it's bloody distracting). I thought Berens might have given us a little moment in reference to it - but the only reference was to joke it away. It may be re-visited when we next see the BMoL, but I'm not holding my breath.
I think the opening "then" with Sam saying 'The devil himself has tortured me, what can you do to me?" is a way of saying "what Sam went through was nothing compared to Hell so he's fine, let's carry on". Either that or he's burying it so damn deep that it he acts has if it never happened. Dean's response to it all has more puzzling, but I figure the entire focus has been Mary's return so Sam's ordeal was merely something to fill the screen with for a couple of episodes (sadly).
The only other real stand out to me was Rowena actually doing something "good" (and being less of a caricature). I was so damn relieved that she was able to get rid of Lucifer rather than her buddy up with him. You go girl!
Loved the motel room (homage to Prince).
Good to see Lucifer's vessel deterioration remembered (though he fixed his vessel last ep so why not this one I wonder?).
I think Mary being possessed at the end (and attacking Dean) might have been a mirror of John being possessed and attacking Dean in Devil's Trap? Cool if it was. Though Sam staying on the floor while Dean was being hurt was weird - I felt liked he'd immediately jump up and tackle possess!Mary. Maybe he didn't want to hurt her.
Mary took John's journal *sadface* (strange I only noticed that on the second viewing). It's clearly her way of connecting with him but it was a real nail in the coffin for Sam and Dean. Not only did they loose their mom but their only connection to their dad was also removed. *sobs* Such an amazing and emotional scene.
Overall it was a light SamnDean episode (and I have a feeling we're going to be getting more of these this season), but that final scene was enough to give us some more layers to their (rather bloody painful) story.