I’ll admit, I had some low expectations going into this episode.  I was actually happy to see that we would be getting something Castiel centric because we don’t get enough Castiel stories given his role in this show.  There is certainly a lot of untapped potential in his background.  “Lily Sundar Has Some Regrets” was an ideal backstory to bring light to Castiel’s current dilemma, one that I don’t think has been effectively put into perspective until now.  At the same time though, this wasn’t exactly a fast paced installment and some other errors prevented it from being a great hour.  
The theme of this season clearly has been parents and children, and this story despite it’s very slow start packed a punch at the end.  It gave a perspective into Castiel’s plight that is  harrowing and tragic.  This is what happens when a grieving mother of a murdered child is left behind.  Lily devoted literally even ounce of her essence and found a way to extend her life to get the revenge she long desired.  The cost to herself was enormous but it didn’t matter.  It was for her child.  They had to pay.  
This did turn out of be an effective character study for our wayward angel.  It makes you realize how much more human Castiel is than angel.  He’s been away from Heaven so long and even when he meets with other angels, he isn’t one of them.  No wonder Castiel has been mopey and lost these past few seasons.  He’s looking for his place in this world and still hasn’t found it.  Well, actually, he has and last week confirmed it, whether Castiel sees it or not.  Killing Billie to save Sam, Dean and Mary means that he is a part of this Winchester clan by doing the greatest act a Winchester can do for another, the act of self sacrifice.  Castiel had put himself in harms way to save his family and no wonder Dean is furious.  Only he gets to do that!  We got to see overprotective big brother and the younger brother placating the rift, acting like families do.  They did have me laughing out loud though when they all crammed into the same booth at the diner.  Only brothers do that!  They are truly a family.
I found it very interesting that Sam, Dean, and especially Castiel related to her plight and assisted in her fight rather than trying to talk her out of it.  Sam and Dean’s goal especially was to convince her that Castiel isn’t the mindless angel he used to be.  Castiel ended up being the one that delivered the fatal blow when Lily wasn’t powerful enough to do so.  That’s quite a different message than “Revenge isn’t worth it,” that we’ve gotten before.  I guess if you think about it, it’s kind of weird.  Killing a bad angel is good, but killing a human isn’t acceptable and killing a good angel isn’t acceptable.  Would they have helped if this was a human she was after?  Who knows, I think the British Men of Letters would have killed all of them, which makes me wonder if Lily turns up dead thanks to Mr. Ketch. Judgment calls aren’t going Sam and Dean’s way these days.  
I’m also very happy to see such a great guest star in Alicia Witt, who played Lily.  Most characters of the week, especially lately, have been wooden and one dimensional.  Witt in her performance delivered such powerful heartache and emotion without ever having to say a word.  Lily’s long gazes and lonely moments in the fleabag hotel told her long story of woe and loneliness.  I was blown away by her look in the mirror as she was healing herself, which in the end was trading her soul for physical strength.  I also loved her talk with Sam.  It’s rather brilliant that she found a way to do powerful magic that could combat angels by channeling the one power that we know through continuity is one of the most powerful forces in the world, the human soul.  We know it’s power when we saw Castiel use Bobby’s soul to get Sam and Dean back in “Frontierland.”  Only those that truly study angels would know that.   The fact that every time she used magic it burned away part of her soul was definitely something Sam could relate to.  Having no soul is a tremendous cost. 
I’m thrilled too to see the return of proper angel lore, something that I have noticed in recent seasons has been ignored or glossed over.  Remember when there were burned wings left behind when angels bit the dust?  We haven’t seen that in a while.  The fact too that the wings now look shabby and light on feathers plays into the whole angels falling arc at the end of season eight.  I also enjoyed hearing the other angels complain to Castiel that getting around earth is a lot harder with burned up wings.  I especially love though that because the angels fell to earth, Lily finally had her opportunity for revenge.  Her patience did pay off.  Kudos to writer Steve Yockey for remembering all those details.
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Castiel’s talk with Sam and Dean at the end was powerful and my heart breaks over what he must face.  He put the earth in jeopardy by using losing Kelly.  Not just any woman pregnant with a nephilim got away.  She’s pregnant with the offspring of an arch angel who happens to be Lucifer.  That’s more powerful than anything that could be unleashed on this earth.  He must stop that.  But, as we saw through Lily’s eyes, they are also a mother and child.  How do you destroy that?  It takes someone truly evil like Ishmir to do such an act and Castiel is not like that.  He has too much humanity in him.  I’ve got to say, I was worried about Castiel after last week and now I’m terrified.  It’s about time he was given a meaty storyline like this.  
I’d like to think that Lily returns sometime to return the favor, to help Castiel in the terrible fight he has coming ahead, not to mention that “consequences” that face him for Billie.  She is without a mission now that her 100 years plus revenge is done (that is assuming Mr. Ketch didn’t find her first) and Castiel's words to her when it was all over had to have left an impression.  It's not often an angel that just saved your life invites you to kill him!  In her case though it would have to be an ultimate act of sacrifice since I would imagine she realizes living with no soul is not an option.  I'm just happy there's a writer around now that can give Castiel that kind of complexity and moral character again.  
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Despite the rather powerful character studies though, something was missing.  Passion, excitement, true raw emotion, that something something that sparks my engagement in an episode.  Normally I would be okay with such breaks in the action if we have actually gotten some action this season.  The first half hour was super bland and I found myself nodding off a lot.  When I wasn’t doing that my internal voice was screaming, “GET ON WITH IT!”  Even daughter, who partially watched with me got bored and left 20 minutes in, only observing that Dean was being a little bitch (her words, not mine!). 
I also have a lot of trouble with the massive break in continuity, angels coming to earth in 1901.  Castiel said that angels haven’t come to earth in 2000 years when he first met Dean, so to hear, “Oh, except that one time I came here on a mission in 1901…” that just doesn’t sit right with me.  I could even believe that present day angels traveled to the past like they did in “The Song Remains The Same,” but that wasn’t the case.  
I don’t know, I wish I loved it.  I just liked it.  This isn’t an episode that I would watch over and over again, but  It was a strong character drama, enhanced by a truly exceptional guest star in Alicia Witt.  On the other side, it was a sleepy episode that didn’t really deliver a “wow” factor, something I’ve been sorely missing this season.  No matter what your preference, you have to admit that the story did have a connection with what is looming large on “Supernatural” this season, even if all it did was tease instead of offer any real substantial clues.  In the land of TV criticism, we call this filler.  It wasn’t bad filler though, so I should be grateful. 
Overall grade, a B.  A little more action in the first half hour and some better dialogue overall could have elevated it to “A” territory, but it almost seems that there’s a mandate to keep it slow this year.