the evolution of Castiel's humanity
I was prompted to write this meta, when it struck me that these two photos - our very first and our most recent images of Castiel - make a powerful statement about his character arc.
When we first met Castiel he was an otherworldly creature, an obedient soldier in Heaven’s army, now he’s an independent agent who's becoming closer to humans than he is to heaven. But he’s not simply changed allegiances; there has been a fundamental shift in his being, the development of something we can call humanity.
Humanity is a big concept to refine - you can cut this cake many ways. You could argue that showing concern for the wellbeing of humans is a fair definition, in which case Castiel exhibited that from when we first met him. It might be about love or loyalty or the ability to post loltastic macros on the internet. But for this meta, I am going to define humanity quite specifically as the ability to make “meaningful, emotional connections”, based on my interpretation of what Kripke’s might define it as, not necessarily because I think this is the best definition, but that it’s the most appropriate one to use for the Show.
If I had a worldview, and I don't know if I do, but if I did, it's one that's intensely humanistic. [That worldview] is that the only thing that matters is family and personal connection, and that's the only thing that gives life meaning. Religion and gods and beliefs -- for me, it all comes down to your brother. And your brother might be the brother in your family, or it might be the guy next to you in the foxhole, it's about human connections. Eric Kripke, interview with Maureen Ryan
What it is to be human is a central theme of the show. It has been examined in many ways but primarily through its characters - Sam in dealing with the “inhuman” part of himself, Dean in facing the loss of his humanity in Hell (but that’s a meta for another day).
The exploration of humanity through a non-human character is a common trope in both scif fi and horror genres- think Spock, Data or Seven of Nine, the Doctor or any number of vampires, or Cylons. In Supernatural we have our angel, Castiel.
The detail of the emotional landscape of angels is never made very clear. We know that they don’t, or can’t, feel emotions they same way we do. (I think we have to accept the archangels - Michael, Lucifer, Gabriel and Rapahel - as a ’special case’ coz they seem to feel things rather passionately!) It’s the reason Anna chose to fall. This of course, precludes them from what I am defining as humanity - that is to form connections with other - because you can’t connect with another being’s emotions, if you can’t connect with your own.
Perfect... Like a marble statue. Cold... No choice... Only obedience.
Anna to Dean “Heaven and Hell”
While we know little of Castiel’s life before he rescued Dean, what is clear is that Castiel was a good angel. We know he is a very capable soldier. He was both obedient and skilled, as indicated by the fact that he has a position of authority in his garrison, and the hierarchy chose him for the crucial mission of both rescuing Dean and overseeing him on Earth.
We also know he has faith. An essential part of Castiel, as I see him, is that he’s a true believer. Alone of all the angels we’ve met Castiel has an unswerving belief in God and his plan. I suspect whatever other talents or skills qualified him for his job on Earth, and with Dean, it was the fact that he was a true believer that was important. Because remember TAPTB (the angel powers that be) had a hidden, terrible agenda so they needed someone who would do his job thoroughly, enthusiastically and most importantly unquestioningly, as long as he thought it was God’s will.
Of course what makes Castiel ultimately exactly the wrong angel for the job, is that as a true believer he also loves God's creations - humans - and it's that ultimately that that sews the seeds of his rebellion and his awakening humanity.
Angels are warriors of god. I'm a soldier.
Castiel to Dean in “Lazarus Rising”
The first few times we meet Castiel, he reminds me of a soldier fighting on foreign soil - sent to another country to help the locals who are under attack, but not really understanding the people or their customs (even simple acts on his part like trying to communicate have disastrous effects). Castiel can't understand why the people he is working to protect seem to think that he and his fellow angels (who are dying in this war) aren't doing enough, or aren't doing the right thing. Hell they aren’t even grateful ("You should show me some respect").
His first interactions with Dean are pretty much strictly business - work out a way to communicate with Dean, tell him about the seals and the plan to free Lucifer, send him back in time so he knows about Azazel.
This is not to say Castiel doesn’t value humans. On the contrary he values them highly because they are God’s creations. Dean is initially important to Castiel because he is a creation of God, and because Castiel has been tasked with Dean’s preparation for what is to come. (Although of course Castiel doesn’t actually know the real, full picture of what this really entails until later). Castiel is told Dean is important to Heaven, and that makes him important to Castiel.
I don’t envy the weight that’s on your shoulders Dean. I truly don’t.
Castiel to Dean in “It’s the Great Pumpkin, Sam Winchester”
But by the events of Halloween, two months after saving Dean, we see a shift in Castiel. He’s getting to know humans, in particular Dean, and this is changing him. The Samhain seal is another impossible situation where the choice is between the sacrifice of few over saving many; like that faced in “Jus In Bello”, there is no clear win here, whatever course of action is followed. Castiel’s orders mean that he knows the outcome is wholly dependant on Dean, and he sees the emotional toll this takes on him. For the first time Castiel, exhibits empathy and, most importantly, shares his own doubts and vulnerability. This is the beginning of a true connection, the first sign of Castiel’s humanity.
Dean: You're some heartless sons of bitches, you know that?
Castiel: As a matter of fact, we are.
“Heaven and Hell”
When we next meet Castiel, he and Uriel are on the mission to capture Anna, and he is acting primarily as the good soldier. The Heavenly rules are that rebellion is punished, and it is also strategically important that the demons do not capture Anna. Again, as a soldier, Castiel is looking at what he thinks is most important - the "bigger" picture.
But despite Castiel’s affirmation that he is “heartless”, when Castiel and Uriel come to kill Anna, Castiel says he is “sorry” about what they are doing. She retorts that he doesn’t know the feeling. “True,” he says, but we have history”.
There is an explicit reference here to Kripke’s definition of humanity, of family. These angels have shared a foxhole, and yet they do not share the type of connection that we see between the human hunters. Castiel refers to something similar in his confrontation with Uriel in “On The Head Of A Pin”. It’s like there’s a template there for connection, but one that is not filled in with emotion. One gets the sense though of Castiel starting to see these connections with his fellow angels now through a different lens. I think we see a hint of this, as he looks away as Dean kisses Anna goodbye, and she forgives him what appears to be his betrayal of her. It’s a small moment, but for me, I read it as an epiphany for Castiel. There is something there between Dean and Anna that Castiel is, I think, just starting to sense is something he wants too.
I was getting too close to the humans in my charge. You. Even to your brother. They feel I've begun to express emotions. The doorways to doubt.
Castiel “On The Head Of A Pin”
“On The Head Of A Pin” is the pivotal episode of the season for all the characters - Dean breaks down, Sam embraces his powers, and Castiel’s connections to Dean and Sam pave the way for his rebellion.
I suspect the angel hierarchy are aware of Castiel's feelings, nto because he's been doodling I Heart Dean in the clouds, but because he's been advocating for Sam and Dean. Most recently he has likely argued against using Dean to torture Alistair. He not only aware of the damage, the cost to Dean, but he cares about it. Also, again this is only speculation, Castiel has possibly argued against the TAPTB attitude to Sam. I imagine they, knowing they need Sam to fully embrace his powers to kill Lilith, have been suggesting actions to encourage this, most likely anything that will drive a wedge between the brothers.
The events in this episode only serve to strengthen the Castiel’s emerging feelings of connection. While Dean protests and resists torturing Alistair, he does it. He does so not just because he understands it's important, but because Castiel asks him, and Dean has a relationship with Castiel.
And this relationship has meaning not only because Castiel saved him from Hell or because he seems an integral part of stopping the apocalypse. I think those alone would not be enough to motivate Dean here. Dean knows Castiel well enough by now to realize that, while they both ostensibly want to stop the apocalypse, his and Castiel’s agendas are not exactly the same. No, it’s the fact that Castiel has shared his doubts and vulnerabilities with Dean, shown that he is prepared to lose something, his status in the garrison, for the relationship.
Castiel's relationship with Sam also changes here. Sam saves his life, gets Castiel the answers he wanted from Alastair, through using his powers. And while Sam's motivations are much more complex than simply helping Castiel, again a human has risked something of himself for Castiel.
Relationships are all about an exchange, about giving, and taking, and that’s what we see here between both the Winchester brothers and Castiel.
We also clearly see in this episode that Castiel’s burgeoning rebellion grows out of these connections, and not simply his doubts about the orders from TAPTB. He rejects Uriel’s path of rebellion - that is too obviously against God’s plan as Castiel perceives it. He initially rejects Anna’s too until his confusion and despair lead him to beg for her guidance. Anna tells him to think for himself and he does using as a template the two things important to him - his belief in God’s plan and his growing humanity.
We see Castiel trying to balance these two parts when Dean prays for his help as Sam sets himself up to confront Lilith, managing to help Dean by letting him know how to use Chuck and his attendant archangel as a 'weapon', without actually intervening. Obeying in action but not in spirit.
Next Castiel takes an even more active step of rebellion, appearing to Dean in a dream, wanting to warn him, presumably about what he knows about the real agenda of TAPTB in relation to the apocalypse. For this he is taken back to Heaven, for what seems to be a combination of painful punishment and reprogramming.
I learned my lesson while I was away Dean. I serve heaven, I don't serve man and I certainly don't serve you.
Castiel, “The Rapture”
One can only imagine whatever was done to Castiel must’ve been quite dire, and has certainly been aimed at removing the nascent humanity from him. We see him back on mission, and seemingly not questioning anymore whether this is really God’s plan. I think these two things - God and humanity - are inextricably linked. Castiel’s rebellion was driven by an innate sense that anything that acts against one’s humanity, that devalues meaningful connections, cannot be God’s plan. TAPTB need to cut Castiel off from his relationships in order to convince him that their plan is the right one.
I think we see something of how the propaganda has worked, in Castiel’s speech to Dean in the Green Room.
What is so worth saving? I see nothing but pain here. I see inside you. I see your guilt, your anger, confusion. In paradise, all is forgiven. You'll be at peace. Even with Sam.
Castiel in “Lucifer Rising”
Castiel has been convinced that these emotions, part of what makes us human, are something to be wished away. Rejected. This is what Castiel has been told - that he certainly shouldn’t want to have feelings, because they bring pain. Dean doesn’t want them - our plan frees Dean from pain.
Dean’s whole arc in season 4 was about connecting with, and accepting, his feelings. Having carried so much pain and guilt from what he did in Hell, he did wish it away, try to repress his feelings, and in doing cut himself off from himself, his humanity, from connections, especially with Sam - which is exactly what Hell was trying to achieve. Because you can’t choose what you feel - you either connect with your feelings - the bad shitty stuff as well as the joyous stuff - or you don’t. And here at the end of the season, Dean finally realizes this, and as his humanity is to him, he is willing to suffer that pain to keep it and the connections it brings.
It is the threat of losing the one tangible evidence of his own humanity, his relationship with Dean - “We're done” - that finally propels Castiel into full scale rebellion against the TAPTB, helping Dean escape and sacrificing his life in the process.
In effect, Castiel chooses his own humanity, over what he has known his whole life. When he is bought back, seemingly by God, this is painful for him as he realizes the magnitude of what he has done.
I killed two angels this week. My brothers. I'm hunted. I rebelled and i did it all of it for you. And you failed. You and your brother destroyed the world. And I lost everything for nothing.
Castiel to Dean in “Lucifer Rising”
Of course, Sam and Dean should’ve passed him a memo that relationships are hard and painful things, but hey I think its one of those lessons that just has to be learned.
Through Season Five so far we have seen Castiel’s connections, his humanity, grow but he still remains a true believer, on his own mission to stop the apocalypse but not alone in it. He asks for help, and likewise helps the Winchester’s with their “insane” plan to retrieve the Colt and use it to try and kill Lucifer.
But we see, as when Castiel tries to kill Jesse, that there will be times when his agenda may be in conflict with Sam and Dean’s, which will challenge the relationships they are building. That, however, is life. Noticeably though, Dean is not angry at Cass after the Jesse incident in the way he would’ve been previously - primarily because of the relationship they now have.
That same episode also provides another insight into Castiel’s emotional development. When with Sam argues that they should let Jesse make “the right choice”, Castiel heatedly retorts that Sam didn’t. As is often the case in this show, I think Castiel’s anger here is a projection of his own anger at himself, his own guilt about the decisions he made, as he has undoubtedly faced his own complicity in starting the apocalypse, particularly in releasing Sam from the panic room (and other actions like betraying Anna). The point is Castiel, is starting to feel things.
Don't ever change.
Dean to Castiel in “The End”
“The End” is an episode which shows us a future where Dean, Sam and Castiel have all lost their humanity. Castiel has lost his in an ironic way - he’s become human for all intents and purposes, and yet he is cutting himself off from emotion as surely as if he was being reprogrammed by Heaven again. Despite his constant smile, there’s a hollowness in him, and there is no sense that through the sex or drugs is Castiel reveling in the joy of feeling, but rather they are a bitter ‘fuck you’ to the universe. There is certainly no sense of deep relationships with those around him, including Dean.
I think I'm starting to feel something.
Castiel to Ellen in “Abandon All Hope”
Finally we come to our most recent meeting with Castiel. The photo Bobby takes is symbolic of where Castiel is now, firmly within the set of strong, family connections these hunters have. Yet his humanity, and these relationships, are not necessarily a permanent thing, as they are not for any of the characters, as this episode so tragically demonstrates.
Supernatural is constantly demonstrating that we must fight to retain our humanity against many threats. It can be taken from us, or we can choose to give it up. It’s our greatest gift and our greatest burden. I think for all the characters, the show continues to reinforce the message that it’s acting in ways informed by our humanity, in ways which value relationships, that is the only “true” way we can act.
I am fascinated to see how Castiel's humanity develops further, how his relationships grow, because that, for him and for Sam and Dean, is what will stop the apocalypse.
When we first met Castiel he was an otherworldly creature, an obedient soldier in Heaven’s army, now he’s an independent agent who's becoming closer to humans than he is to heaven. But he’s not simply changed allegiances; there has been a fundamental shift in his being, the development of something we can call humanity.
Humanity is a big concept to refine - you can cut this cake many ways. You could argue that showing concern for the wellbeing of humans is a fair definition, in which case Castiel exhibited that from when we first met him. It might be about love or loyalty or the ability to post loltastic macros on the internet. But for this meta, I am going to define humanity quite specifically as the ability to make “meaningful, emotional connections”, based on my interpretation of what Kripke’s might define it as, not necessarily because I think this is the best definition, but that it’s the most appropriate one to use for the Show.
If I had a worldview, and I don't know if I do, but if I did, it's one that's intensely humanistic. [That worldview] is that the only thing that matters is family and personal connection, and that's the only thing that gives life meaning. Religion and gods and beliefs -- for me, it all comes down to your brother. And your brother might be the brother in your family, or it might be the guy next to you in the foxhole, it's about human connections. Eric Kripke, interview with Maureen Ryan
What it is to be human is a central theme of the show. It has been examined in many ways but primarily through its characters - Sam in dealing with the “inhuman” part of himself, Dean in facing the loss of his humanity in Hell (but that’s a meta for another day).
The exploration of humanity through a non-human character is a common trope in both scif fi and horror genres- think Spock, Data or Seven of Nine, the Doctor or any number of vampires, or Cylons. In Supernatural we have our angel, Castiel.
The detail of the emotional landscape of angels is never made very clear. We know that they don’t, or can’t, feel emotions they same way we do. (I think we have to accept the archangels - Michael, Lucifer, Gabriel and Rapahel - as a ’special case’ coz they seem to feel things rather passionately!) It’s the reason Anna chose to fall. This of course, precludes them from what I am defining as humanity - that is to form connections with other - because you can’t connect with another being’s emotions, if you can’t connect with your own.
Perfect... Like a marble statue. Cold... No choice... Only obedience.
Anna to Dean “Heaven and Hell”
While we know little of Castiel’s life before he rescued Dean, what is clear is that Castiel was a good angel. We know he is a very capable soldier. He was both obedient and skilled, as indicated by the fact that he has a position of authority in his garrison, and the hierarchy chose him for the crucial mission of both rescuing Dean and overseeing him on Earth.
We also know he has faith. An essential part of Castiel, as I see him, is that he’s a true believer. Alone of all the angels we’ve met Castiel has an unswerving belief in God and his plan. I suspect whatever other talents or skills qualified him for his job on Earth, and with Dean, it was the fact that he was a true believer that was important. Because remember TAPTB (the angel powers that be) had a hidden, terrible agenda so they needed someone who would do his job thoroughly, enthusiastically and most importantly unquestioningly, as long as he thought it was God’s will.
Of course what makes Castiel ultimately exactly the wrong angel for the job, is that as a true believer he also loves God's creations - humans - and it's that ultimately that that sews the seeds of his rebellion and his awakening humanity.
Angels are warriors of god. I'm a soldier.
Castiel to Dean in “Lazarus Rising”
The first few times we meet Castiel, he reminds me of a soldier fighting on foreign soil - sent to another country to help the locals who are under attack, but not really understanding the people or their customs (even simple acts on his part like trying to communicate have disastrous effects). Castiel can't understand why the people he is working to protect seem to think that he and his fellow angels (who are dying in this war) aren't doing enough, or aren't doing the right thing. Hell they aren’t even grateful ("You should show me some respect").
His first interactions with Dean are pretty much strictly business - work out a way to communicate with Dean, tell him about the seals and the plan to free Lucifer, send him back in time so he knows about Azazel.
This is not to say Castiel doesn’t value humans. On the contrary he values them highly because they are God’s creations. Dean is initially important to Castiel because he is a creation of God, and because Castiel has been tasked with Dean’s preparation for what is to come. (Although of course Castiel doesn’t actually know the real, full picture of what this really entails until later). Castiel is told Dean is important to Heaven, and that makes him important to Castiel.
I don’t envy the weight that’s on your shoulders Dean. I truly don’t.
Castiel to Dean in “It’s the Great Pumpkin, Sam Winchester”
But by the events of Halloween, two months after saving Dean, we see a shift in Castiel. He’s getting to know humans, in particular Dean, and this is changing him. The Samhain seal is another impossible situation where the choice is between the sacrifice of few over saving many; like that faced in “Jus In Bello”, there is no clear win here, whatever course of action is followed. Castiel’s orders mean that he knows the outcome is wholly dependant on Dean, and he sees the emotional toll this takes on him. For the first time Castiel, exhibits empathy and, most importantly, shares his own doubts and vulnerability. This is the beginning of a true connection, the first sign of Castiel’s humanity.
Dean: You're some heartless sons of bitches, you know that?
Castiel: As a matter of fact, we are.
“Heaven and Hell”
When we next meet Castiel, he and Uriel are on the mission to capture Anna, and he is acting primarily as the good soldier. The Heavenly rules are that rebellion is punished, and it is also strategically important that the demons do not capture Anna. Again, as a soldier, Castiel is looking at what he thinks is most important - the "bigger" picture.
But despite Castiel’s affirmation that he is “heartless”, when Castiel and Uriel come to kill Anna, Castiel says he is “sorry” about what they are doing. She retorts that he doesn’t know the feeling. “True,” he says, but we have history”.
There is an explicit reference here to Kripke’s definition of humanity, of family. These angels have shared a foxhole, and yet they do not share the type of connection that we see between the human hunters. Castiel refers to something similar in his confrontation with Uriel in “On The Head Of A Pin”. It’s like there’s a template there for connection, but one that is not filled in with emotion. One gets the sense though of Castiel starting to see these connections with his fellow angels now through a different lens. I think we see a hint of this, as he looks away as Dean kisses Anna goodbye, and she forgives him what appears to be his betrayal of her. It’s a small moment, but for me, I read it as an epiphany for Castiel. There is something there between Dean and Anna that Castiel is, I think, just starting to sense is something he wants too.
I was getting too close to the humans in my charge. You. Even to your brother. They feel I've begun to express emotions. The doorways to doubt.
Castiel “On The Head Of A Pin”
“On The Head Of A Pin” is the pivotal episode of the season for all the characters - Dean breaks down, Sam embraces his powers, and Castiel’s connections to Dean and Sam pave the way for his rebellion.
I suspect the angel hierarchy are aware of Castiel's feelings, nto because he's been doodling I Heart Dean in the clouds, but because he's been advocating for Sam and Dean. Most recently he has likely argued against using Dean to torture Alistair. He not only aware of the damage, the cost to Dean, but he cares about it. Also, again this is only speculation, Castiel has possibly argued against the TAPTB attitude to Sam. I imagine they, knowing they need Sam to fully embrace his powers to kill Lilith, have been suggesting actions to encourage this, most likely anything that will drive a wedge between the brothers.
The events in this episode only serve to strengthen the Castiel’s emerging feelings of connection. While Dean protests and resists torturing Alistair, he does it. He does so not just because he understands it's important, but because Castiel asks him, and Dean has a relationship with Castiel.
And this relationship has meaning not only because Castiel saved him from Hell or because he seems an integral part of stopping the apocalypse. I think those alone would not be enough to motivate Dean here. Dean knows Castiel well enough by now to realize that, while they both ostensibly want to stop the apocalypse, his and Castiel’s agendas are not exactly the same. No, it’s the fact that Castiel has shared his doubts and vulnerabilities with Dean, shown that he is prepared to lose something, his status in the garrison, for the relationship.
Castiel's relationship with Sam also changes here. Sam saves his life, gets Castiel the answers he wanted from Alastair, through using his powers. And while Sam's motivations are much more complex than simply helping Castiel, again a human has risked something of himself for Castiel.
Relationships are all about an exchange, about giving, and taking, and that’s what we see here between both the Winchester brothers and Castiel.
We also clearly see in this episode that Castiel’s burgeoning rebellion grows out of these connections, and not simply his doubts about the orders from TAPTB. He rejects Uriel’s path of rebellion - that is too obviously against God’s plan as Castiel perceives it. He initially rejects Anna’s too until his confusion and despair lead him to beg for her guidance. Anna tells him to think for himself and he does using as a template the two things important to him - his belief in God’s plan and his growing humanity.
We see Castiel trying to balance these two parts when Dean prays for his help as Sam sets himself up to confront Lilith, managing to help Dean by letting him know how to use Chuck and his attendant archangel as a 'weapon', without actually intervening. Obeying in action but not in spirit.
Next Castiel takes an even more active step of rebellion, appearing to Dean in a dream, wanting to warn him, presumably about what he knows about the real agenda of TAPTB in relation to the apocalypse. For this he is taken back to Heaven, for what seems to be a combination of painful punishment and reprogramming.
I learned my lesson while I was away Dean. I serve heaven, I don't serve man and I certainly don't serve you.
Castiel, “The Rapture”
One can only imagine whatever was done to Castiel must’ve been quite dire, and has certainly been aimed at removing the nascent humanity from him. We see him back on mission, and seemingly not questioning anymore whether this is really God’s plan. I think these two things - God and humanity - are inextricably linked. Castiel’s rebellion was driven by an innate sense that anything that acts against one’s humanity, that devalues meaningful connections, cannot be God’s plan. TAPTB need to cut Castiel off from his relationships in order to convince him that their plan is the right one.
I think we see something of how the propaganda has worked, in Castiel’s speech to Dean in the Green Room.
What is so worth saving? I see nothing but pain here. I see inside you. I see your guilt, your anger, confusion. In paradise, all is forgiven. You'll be at peace. Even with Sam.
Castiel in “Lucifer Rising”
Castiel has been convinced that these emotions, part of what makes us human, are something to be wished away. Rejected. This is what Castiel has been told - that he certainly shouldn’t want to have feelings, because they bring pain. Dean doesn’t want them - our plan frees Dean from pain.
Dean’s whole arc in season 4 was about connecting with, and accepting, his feelings. Having carried so much pain and guilt from what he did in Hell, he did wish it away, try to repress his feelings, and in doing cut himself off from himself, his humanity, from connections, especially with Sam - which is exactly what Hell was trying to achieve. Because you can’t choose what you feel - you either connect with your feelings - the bad shitty stuff as well as the joyous stuff - or you don’t. And here at the end of the season, Dean finally realizes this, and as his humanity is to him, he is willing to suffer that pain to keep it and the connections it brings.
It is the threat of losing the one tangible evidence of his own humanity, his relationship with Dean - “We're done” - that finally propels Castiel into full scale rebellion against the TAPTB, helping Dean escape and sacrificing his life in the process.
In effect, Castiel chooses his own humanity, over what he has known his whole life. When he is bought back, seemingly by God, this is painful for him as he realizes the magnitude of what he has done.
I killed two angels this week. My brothers. I'm hunted. I rebelled and i did it all of it for you. And you failed. You and your brother destroyed the world. And I lost everything for nothing.
Castiel to Dean in “Lucifer Rising”
Of course, Sam and Dean should’ve passed him a memo that relationships are hard and painful things, but hey I think its one of those lessons that just has to be learned.
Through Season Five so far we have seen Castiel’s connections, his humanity, grow but he still remains a true believer, on his own mission to stop the apocalypse but not alone in it. He asks for help, and likewise helps the Winchester’s with their “insane” plan to retrieve the Colt and use it to try and kill Lucifer.
But we see, as when Castiel tries to kill Jesse, that there will be times when his agenda may be in conflict with Sam and Dean’s, which will challenge the relationships they are building. That, however, is life. Noticeably though, Dean is not angry at Cass after the Jesse incident in the way he would’ve been previously - primarily because of the relationship they now have.
That same episode also provides another insight into Castiel’s emotional development. When with Sam argues that they should let Jesse make “the right choice”, Castiel heatedly retorts that Sam didn’t. As is often the case in this show, I think Castiel’s anger here is a projection of his own anger at himself, his own guilt about the decisions he made, as he has undoubtedly faced his own complicity in starting the apocalypse, particularly in releasing Sam from the panic room (and other actions like betraying Anna). The point is Castiel, is starting to feel things.
Don't ever change.
Dean to Castiel in “The End”
“The End” is an episode which shows us a future where Dean, Sam and Castiel have all lost their humanity. Castiel has lost his in an ironic way - he’s become human for all intents and purposes, and yet he is cutting himself off from emotion as surely as if he was being reprogrammed by Heaven again. Despite his constant smile, there’s a hollowness in him, and there is no sense that through the sex or drugs is Castiel reveling in the joy of feeling, but rather they are a bitter ‘fuck you’ to the universe. There is certainly no sense of deep relationships with those around him, including Dean.
I think I'm starting to feel something.
Castiel to Ellen in “Abandon All Hope”
Finally we come to our most recent meeting with Castiel. The photo Bobby takes is symbolic of where Castiel is now, firmly within the set of strong, family connections these hunters have. Yet his humanity, and these relationships, are not necessarily a permanent thing, as they are not for any of the characters, as this episode so tragically demonstrates.
Supernatural is constantly demonstrating that we must fight to retain our humanity against many threats. It can be taken from us, or we can choose to give it up. It’s our greatest gift and our greatest burden. I think for all the characters, the show continues to reinforce the message that it’s acting in ways informed by our humanity, in ways which value relationships, that is the only “true” way we can act.
I am fascinated to see how Castiel's humanity develops further, how his relationships grow, because that, for him and for Sam and Dean, is what will stop the apocalypse.